Pcache.cpp

Go to the documentation of this file.

/****************************************************************************************/
/*  PCache.cpp                                                                          */
/*                                                                                      */
/*  Author: John Pollard                                                                */
/*  Description: D3D poly cache                                                         */
/*                                                                                      */
/*  The contents of this file are subject to the Genesis3D Public License               */
/*  Version 1.01 (the "License"); you may not use this file except in                   */
/*  compliance with the License. You may obtain a copy of the License at                */
/*  http://www.genesis3d.com                                                            */
/*                                                                                      */
/*  Software distributed under the License is distributed on an "AS IS"                 */
/*  basis, WITHOUT WARRANTY OF ANY KIND, either express or implied.  See                */
/*  the License for the specific language governing rights and limitations              */
/*  under the License.                                                                  */
/*                                                                                      */
/*  The Original Code is Genesis3D, released March 25, 1999.                            */
/*Genesis3D Version 1.1 released November 15, 1999                            */
/*  Copyright (C) 1999 WildTangent, Inc. All Rights Reserved           */
/*                                                                                      */
/****************************************************************************************/
#include <Windows.h>
#include <stdio.h>

#include "D3DCache.h"
#include "D3D_Fx.h"

#include "PCache.h"
#include "D3DDrv.h"
#include "THandle.h"
#include "D3D_Err.h"


//#define D3D_MANAGE_TEXTURES
//#define SUPER_FLUSH

//====================================================================================
//      Local static variables
//====================================================================================

DRV_CacheInfo                                           CacheInfo;

//
//      World Cache
//

#if 1

#define MAX_WORLD_POLYS                         512
#define MAX_WORLD_POLY_VERTS            2048

#define MAX_MISC_POLYS                          512
#define MAX_MISC_POLY_VERTS                     2048

#else

#define MAX_WORLD_POLYS                         256
#define MAX_WORLD_POLY_VERTS            4096

#define MAX_MISC_POLYS                          256
#define MAX_MISC_POLY_VERTS                     4096

#endif

typedef struct
{
        geFloat         u;
        geFloat         v;
        //geFloat               a;
        uint32          Color;
} PCache_TVert;

typedef struct
{
        geRDriver_THandle       *THandle;

        DRV_LInfo       *LInfo;                                         // Original pointer to linfo
        uint32          Flags;                                          // Flags for this poly
        geFloat         ShiftU;
        geFloat         ShiftV;
        geFloat         ScaleU;
        geFloat         ScaleV;
        int32           MipLevel;
        uint32          SortKey;
        int32           FirstVert;
        int32           NumVerts;
} World_Poly;

#define MAX_TEXTURE_STAGES              2                       // Up to 2 tmu's (stages)

// Verts we defined in the D3D flexible vertex format (FVF)
// This is a transformed and lit vertex definition, with up to 8 sets of uvs
typedef struct
{
        geFloat                 u,v;
} PCache_UVSet;

typedef struct
{
        geFloat                 x,y,z;                                  // Screen x, y, z
        geFloat                 rhw;                                    // homogenous w
        DWORD                   color;                                  // color
        DWORD                   specular;
        PCache_UVSet    uv[MAX_TEXTURE_STAGES]; // uv sets for each stage
} PCache_Vert;

typedef struct
{
        World_Poly              Polys[MAX_WORLD_POLYS];
        World_Poly              *SortedPolys[MAX_WORLD_POLYS];
        World_Poly              *SortedPolys2[MAX_WORLD_POLYS];
        PCache_Vert             Verts[MAX_WORLD_POLY_VERTS];

        PCache_TVert    TVerts[MAX_WORLD_POLY_VERTS];           // Original uv

        int32                   NumPolys;
        int32                   NumPolys2;
        int32                   NumVerts;
} World_Cache;

static World_Cache              WorldCache;

#define PREP_WORLD_VERTS_NORMAL                 1                               // Prep verts as normal
#define PREP_WORLD_VERTS_LMAP                   2                               // Prep verts as lightmaps
#define PREP_WORLD_VERTS_SINGLE_PASS    3                               // Prep verts for a single pass

#define RENDER_WORLD_POLYS_NORMAL               1                               // Render polys as normal
#define RENDER_WORLD_POLYS_LMAP                 2                               // Render polys as lightmaps
#define RENDER_WORLD_POLYS_SINGLE_PASS  3

//
//      Misc cache
//

typedef struct
{
        geRDriver_THandle       *THandle;
        uint32          Flags;                                          // Flags for this poly
        int32           MipLevel;
        int32           FirstVert;
        int32           NumVerts;

        uint32          SortKey;
} Misc_Poly;

typedef struct
{
        Misc_Poly               Polys[MAX_MISC_POLYS];
        Misc_Poly               *SortedPolys[MAX_MISC_POLYS];
        PCache_Vert             Verts[MAX_MISC_POLY_VERTS];
        //geFloat                       ZVert[MAX_MISC_POLY_VERTS];

        int32                   NumPolys;
        int32                   NumVerts;
} Misc_Cache;

static Misc_Cache               MiscCache;

//====================================================================================
//      Local static functions prototypes
//====================================================================================
geBoolean World_PolyPrepVerts(World_Poly *pPoly, int32 PrepMode, int32 Stage1, int32 Stage2);

static BOOL RenderWorldPolys(int32 RenderMode);
static BOOL ClearWorldCache(void);
static int32 GetMipLevel(DRV_TLVertex *Verts, int32 NumVerts, geFloat ScaleU, geFloat ScaleV, int32 MaxMipLevel);

#include <Math.h>

//====================================================================================
//      PCache_InsertWorldPoly
//====================================================================================
BOOL PCache_InsertWorldPoly(DRV_TLVertex *Verts, int32 NumVerts, geRDriver_THandle *THandle, DRV_TexInfo *TexInfo, DRV_LInfo *LInfo, uint32 Flags)
{
        int32                   Mip;
        geFloat                 ZRecip, DrawScaleU, DrawScaleV;
        World_Poly              *pCachePoly;
        DRV_TLVertex    *pVerts;
        PCache_TVert    *pTVerts;
        PCache_Vert             *pD3DVerts;
        int32                   i;
        uint32                  Alpha;

        #ifdef _DEBUG
                if (LInfo)
                {
                        assert(LInfo->THandle);
                }
        #endif

        if ((WorldCache.NumVerts + NumVerts) >= MAX_WORLD_POLY_VERTS)
        {
                // If the cache is full, we must flush it before going on...
                if (!PCache_FlushWorldPolys())
                        return GE_FALSE;
        }
        else if (WorldCache.NumPolys+1 >= MAX_WORLD_POLYS)
        {
                // If the cache is full, we must flush it before going on...
                if (!PCache_FlushWorldPolys())
                        return GE_FALSE;
        }

        DrawScaleU = 1.0f / TexInfo->DrawScaleU;
        DrawScaleV = 1.0f / TexInfo->DrawScaleV;

        Mip = GetMipLevel(Verts, NumVerts, DrawScaleU, DrawScaleV, THandle->NumMipLevels-1);

        // Get a pointer to the original polys verts
        pVerts = Verts;
        
        // Store info about this poly in the cache
        pCachePoly = &WorldCache.Polys[WorldCache.NumPolys];

        pCachePoly->THandle = THandle;
        pCachePoly->LInfo = LInfo;
        pCachePoly->Flags = Flags;
        pCachePoly->FirstVert = WorldCache.NumVerts;
        pCachePoly->NumVerts = NumVerts;
        pCachePoly->ShiftU = TexInfo->ShiftU;
        pCachePoly->ShiftV = TexInfo->ShiftV;
        pCachePoly->ScaleU = DrawScaleU;
        pCachePoly->ScaleV = DrawScaleV;
        pCachePoly->MipLevel = Mip;

        // Don't forget the sort key:
        pCachePoly->SortKey = ((THandle - TextureHandles)<<4)+Mip;

        // Get a pointer into the world verts
        pD3DVerts = &WorldCache.Verts[WorldCache.NumVerts];
        pTVerts = &WorldCache.TVerts[WorldCache.NumVerts];

        if (Flags & DRV_RENDER_ALPHA)
                Alpha = (uint32)pVerts->a<<24;
        else
                Alpha = (uint32)(255<<24);

        for (i=0; i< NumVerts; i++)
        {
                ZRecip = 1.0f/(pVerts->z);

                pD3DVerts->x = pVerts->x;
                pD3DVerts->y = pVerts->y;

                pD3DVerts->z = (1.0f - ZRecip); // ZBUFFER
                pD3DVerts->rhw = ZRecip;

                if (AppInfo.FogEnable && !(Flags & DRV_RENDER_POLY_NO_FOG)) // poly fog
                {
                        DWORD   FogVal;
                        geFloat Val;

                        Val = pVerts->z;

                        if (Val > AppInfo.FogEnd)
                                Val = AppInfo.FogEnd;

                        FogVal = (DWORD)((AppInfo.FogEnd-Val)/(AppInfo.FogEnd-AppInfo.FogStart)*255.0f);
                
                        if (FogVal < 0)
                                FogVal = 0;
                        else if (FogVal > 255)
                                FogVal = 255;
                
                        pD3DVerts->specular = (FogVal<<24);             // Alpha component in specular is the fog value (0...255)
                }
                else
                        pD3DVerts->specular = 0;
                
                // Store the uv's so the prep pass can use them...
                pTVerts->u = pVerts->u;
                pTVerts->v = pVerts->v;

                pTVerts->Color = Alpha | ((uint32)pVerts->r<<16) | ((uint32)pVerts->g<<8) | (uint32)pVerts->b;

                pTVerts++;
                pVerts++;        
                pD3DVerts++;

        }
        
        // Update globals about the world poly cache
        WorldCache.NumVerts += NumVerts;
        WorldCache.NumPolys++;

        return TRUE;
}

//====================================================================================
//      PCache_FlushWorldPolys
//====================================================================================
BOOL PCache_FlushWorldPolys(void)
{
        if (!WorldCache.NumPolys)
                return TRUE;

        if (!THandle_CheckCache())
                return GE_FALSE;
        
        if (AppInfo.CanDoMultiTexture)
        {
                RenderWorldPolys(RENDER_WORLD_POLYS_SINGLE_PASS);
        }
        else
        {
                // Render them as normal
                if (!RenderWorldPolys(RENDER_WORLD_POLYS_NORMAL))
                        return GE_FALSE;

                // Render them as lmaps
                RenderWorldPolys(RENDER_WORLD_POLYS_LMAP);
        }

        ClearWorldCache();

        return TRUE;
}

//====================================================================================
//====================================================================================
static int MiscBitmapHandleComp(const void *a, const void *b)
{
        uint32  Id1, Id2;

        Id1 = (uint32)(*(Misc_Poly**)a)->SortKey;
        Id2 = (uint32)(*(Misc_Poly**)b)->SortKey;

        if ( Id1 == Id2)
                return 0;

        if (Id1 < Id2)
                return -1;

        return 1;
}

//====================================================================================
//====================================================================================
static void SortMiscPolysByHandle(void)
{
        Misc_Poly       *pPoly;
        int32           i;

        pPoly = MiscCache.Polys;

        for (i=0; i<MiscCache.NumPolys; i++)
        {
                MiscCache.SortedPolys[i] = pPoly;
                pPoly++;
        }
        
        // Sort the polys
        qsort(&MiscCache.SortedPolys, MiscCache.NumPolys, sizeof(MiscCache.SortedPolys[0]), MiscBitmapHandleComp);
}

//=====================================================================================
//      FillLMapSurface
//=====================================================================================
static void FillLMapSurface(DRV_LInfo *LInfo, int32 LNum)
{
        U16                                     *pTempBits;
        int32                           w, h, Width, Height, Size;
        U8                                      *pBitPtr;
        RGB_LUT                         *Lut;
        geRDriver_THandle       *THandle;
        int32                           Extra;

        THandle = LInfo->THandle;

        pBitPtr = (U8*)LInfo->RGBLight[LNum];

        Width = LInfo->Width;
        Height = LInfo->Height;
        Size = 1<<THandle->Log;

        Lut = &AppInfo.Lut1;

        THandle_Lock(THandle, 0, (void**)&pTempBits);

        Extra = Size - Width;
        U8      R, G, B;
        U16     Color;

        for (h=0; h< Height; h++)
        {
                for (w=0; w< Width; w++)
                {
                        R = *pBitPtr++;
                        G = *pBitPtr++;
                        B =  *pBitPtr++;
                        
                        Color = (U16)(Lut->R[R] | Lut->G[G] | Lut->B[B]);

                        *pTempBits++ = Color;
                }
                pTempBits += Extra;
        }

        THandle_UnLock(THandle, 0);
}

#ifdef USE_TPAGES
//=====================================================================================
//      FillLMapSurface
//=====================================================================================
static void FillLMapSurface2(DRV_LInfo *LInfo, int32 LNum)
{
        U16                                     *pTempBits;
        int32                           w, h, Width, Height, Stride;
        U8                                      *pBitPtr;
        RGB_LUT                         *Lut;
        geRDriver_THandle       *THandle;
        HRESULT                         Result;
        const RECT                      *pRect;
    DDSURFACEDESC2              SurfDesc;
        LPDIRECTDRAWSURFACE4    Surface;
        int32                           Extra;

        THandle = LInfo->THandle;

        pBitPtr = (U8*)LInfo->RGBLight[LNum];

        Width = LInfo->Width;
        Height = LInfo->Height;

        Lut = &AppInfo.Lut1;

    pRect = TPage_BlockGetRect(THandle->Block);
        Surface = TPage_BlockGetSurface(THandle->Block);

    memset(&SurfDesc, 0, sizeof(DDSURFACEDESC2));
    SurfDesc.dwSize = sizeof(DDSURFACEDESC2);

        Result = Surface->Lock((RECT*)pRect, &SurfDesc, DDLOCK_WAIT, NULL);

        assert(Result == DD_OK);

        Stride = SurfDesc.dwWidth;

        pTempBits = (U16*)SurfDesc.lpSurface;

        Extra = Stride - Width; 

        for (h=0; h< Height; h++)
        {
                for (w=0; w< Width; w++)
                {
                        U8      R, G, B;
                        U16     Color;
                        R = *pBitPtr++;
                        G = *pBitPtr++;
                        B = *pBitPtr++;
                        
                        Color = (U16)(Lut->R[R] | Lut->G[G] | Lut->B[B]);

                        *pTempBits++ = Color;
                }
                pTempBits += Extra;
        }

    Result = Surface->Unlock((RECT*)pRect);

        assert(Result == DD_OK);
}
#endif

//=====================================================================================
//      LoadLMapFromSystem
//=====================================================================================
static void LoadLMapFromSystem(DRV_LInfo *LInfo, int32 Log, int32 LNum)
{
        U16                                     *pTempBits;
        int32                           w, h, Width, Height, Size, Extra;
        U8                                      *pBitPtr;
        LPDIRECTDRAWSURFACE4 Surface;
        RGB_LUT                         *Lut;
    DDSURFACEDESC2              ddsd;
    HRESULT                             ddrval;

        pBitPtr = (U8*)LInfo->RGBLight[LNum];

        Width = LInfo->Width;
        Height = LInfo->Height;
        Size = 1<<Log;

        Extra = Size - Width;

        Lut = &AppInfo.Lut1;

        Surface = SystemToVideo[Log].Surface;

    memset(&ddsd, 0, sizeof(DDSURFACEDESC2));
    ddsd.dwSize = sizeof(DDSURFACEDESC2);
    ddrval = Surface->Lock(NULL, &ddsd, DDLOCK_WAIT, NULL);

        assert(ddrval == DD_OK);
        U8      R, G, B;
        U16     Color;

        pTempBits = (USHORT*)ddsd.lpSurface;

        for (h=0; h< Height; h++)
        {
                for (w=0; w< Width; w++)
                {
                        R = *pBitPtr++;
                        G = *pBitPtr++;
                        B =  *pBitPtr++;
                        
                        Color = (U16)(Lut->R[R] | Lut->G[G] | Lut->B[B]);
                        
                        *pTempBits++ = Color;
                }
                pTempBits += Extra;
        }

    ddrval = Surface->Unlock(NULL);
        assert(ddrval == DD_OK);
}

static BOOL IsKeyDown(int KeyCode)
{
        if (GetAsyncKeyState(KeyCode) & 0x8000)
                return TRUE;

        return FALSE;
}

extern uint32 CurrentLRU;

//=====================================================================================
//      SetupMipData
//=====================================================================================
geBoolean SetupMipData(THandle_MipData *MipData)
{
        if (!MipData->Slot || D3DCache_SlotGetUserData(MipData->Slot) != MipData)
        {
                MipData->Slot = D3DCache_TypeFindSlot(MipData->CacheType);
                assert(MipData->Slot);

                D3DCache_SlotSetUserData(MipData->Slot, MipData);

        #ifdef SUPER_FLUSH
                AppInfo.lpD3DDevice->SetRenderState(D3DRENDERSTATE_FLUSHBATCH, 0);
        #endif

                return GE_FALSE;
        }

        return GE_TRUE;
}

//=====================================================================================
//      SetupLMap
//=====================================================================================
geBoolean SetupLMap(int32 Stage, DRV_LInfo *LInfo, int32 LNum, geBoolean Dynamic)
{
#ifdef D3D_MANAGE_TEXTURES
        #ifdef USE_TPAGES
        {
                geRDriver_THandle               *THandle;

                THandle = LInfo->THandle;

                if (Dynamic)
                        THandle->Flags |= THANDLE_UPDATE;

                if (!THandle->Block)
                {
                        THandle->Block = TPage_MgrFindOptimalBlock(TPageMgr, CurrentLRU);
                        THandle->Flags |= THANDLE_UPDATE;
                        TPage_BlockSetUserData(THandle->Block, THandle);
                        assert(THandle->Block);
                }
                else if (TPage_BlockGetUserData(THandle->Block) != THandle)
                {
                        // Find another block
                        THandle->Block = TPage_MgrFindOptimalBlock(TPageMgr, CurrentLRU);
                        assert(THandle->Block);

                        THandle->Flags |= THANDLE_UPDATE;
                        TPage_BlockSetUserData(THandle->Block, THandle);
                }

                if (THandle->Flags & THANDLE_UPDATE)
                        FillLMapSurface2(LInfo, LNum);

                TPage_BlockSetLRU(THandle->Block, CurrentLRU);
                D3DSetTexture(Stage, TPage_BlockGetTexture(THandle->Block));
        
                if (Dynamic)
                        THandle->Flags |= THANDLE_UPDATE;
                else
                        THandle->Flags &= ~THANDLE_UPDATE;

                return GE_TRUE;
        }
        #else
        {
                geRDriver_THandle               *THandle;

                THandle = LInfo->THandle;

                if (Dynamic)
                        THandle->MipData[0].Flags |= THANDLE_UPDATE;

                if (THandle->MipData[0].Flags & THANDLE_UPDATE)
                        FillLMapSurface(LInfo, LNum);

                D3DSetTexture(Stage, THandle->MipData[0].Texture);
        
                if (Dynamic)
                        THandle->MipData[0].Flags |= THANDLE_UPDATE;
                else
                        THandle->MipData[0].Flags &= ~THANDLE_UPDATE;

                return GE_TRUE;
        }
        #endif

#else
        geRDriver_THandle       *THandle;
        THandle_MipData         *MipData;

        THandle = LInfo->THandle;
        MipData = &THandle->MipData[0];

        if (Dynamic)
                MipData->Flags |= THANDLE_UPDATE;

        if (!SetupMipData(MipData))
        {
                MipData->Flags |= THANDLE_UPDATE;               // Force an upload
                CacheInfo.LMapMisses++;
        }

        if (MipData->Flags & THANDLE_UPDATE)
        {
                HRESULT                                 Error;
                LPDIRECTDRAWSURFACE4    Surface;

                assert(MipData->Slot);
                
                Surface = D3DCache_SlotGetSurface(MipData->Slot);

                assert(Surface);
                assert(THandle->Log < MAX_LMAP_LOG_SIZE);
                assert(SystemToVideo[THandle->Log].Surface);

                LoadLMapFromSystem(LInfo, THandle->Log, LNum);

                Error = Surface->BltFast(0, 0, SystemToVideo[THandle->Log].Surface, NULL, DDBLTFAST_WAIT);
                //Error = Surface->BltFast(0, 0, SystemToVideo[THandle->Log].Surface, NULL, 0);
                //Error = Surface->Blt(NULL, SystemToVideo[THandle->Log].Surface, NULL, DDBLT_WAIT, NULL);
                //Error = Surface->Blt(NULL, SystemToVideo[THandle->Log].Surface, NULL, 0, NULL);
                
                if (Error != DD_OK)
                {
                        if(Error==DDERR_SURFACELOST)
                        {
                                if (!D3DMain_RestoreAllSurfaces())
                                        return GE_FALSE;
                        }
                        else
                        {
                                D3DMain_Log("SetupTexture: System to Video cache Blt failed.\n %s", D3DErrorToString(Error));
                                return GE_FALSE;
                        }
                }
        }

        if (Dynamic)            // If it was dynmamic, force an update for one more frame
                MipData->Flags |= THANDLE_UPDATE;
        else
                MipData->Flags &= ~THANDLE_UPDATE;

        D3DCache_SlotSetLRU(MipData->Slot, CurrentLRU);
        D3DSetTexture(Stage, D3DCache_SlotGetTexture(MipData->Slot));

        return GE_TRUE;
#endif
}

//=====================================================================================
//      SetupTexture
//=====================================================================================
geBoolean SetupTexture(int32 Stage, geRDriver_THandle *THandle, int32 MipLevel)
{
#ifdef D3D_MANAGE_TEXTURES
        D3DSetTexture(Stage, THandle->MipData[MipLevel].Texture);
        return GE_TRUE;
#else
        THandle_MipData         *MipData;

        MipData = &THandle->MipData[MipLevel];
        
        if (!SetupMipData(MipData))
        {
                MipData->Flags |= THANDLE_UPDATE;               // Force an upload
                CacheInfo.TexMisses++;
        }

        if (MipData->Flags & THANDLE_UPDATE)
        {
                HRESULT                                 Error;
                LPDIRECTDRAWSURFACE4    Surface;

                Surface = D3DCache_SlotGetSurface(MipData->Slot);

                Error = Surface->BltFast(0, 0, MipData->Surface, NULL, DDBLTFAST_WAIT);

                if (Error != DD_OK)
                {
                        if(Error==DDERR_SURFACELOST)
                        {
                                if (!D3DMain_RestoreAllSurfaces())
                                        return FALSE;
                        }
                        else
                        {
                                D3DMain_Log("SetupTexture: System to Video cache Blt failed.\n %s", D3DErrorToString(Error));
                                return GE_FALSE;
                        }
                }
        }

        MipData->Flags &= ~THANDLE_UPDATE;

        D3DCache_SlotSetLRU(MipData->Slot, CurrentLRU);
        D3DSetTexture(Stage, D3DCache_SlotGetTexture(MipData->Slot));

        return GE_TRUE;
#endif
}

//====================================================================================
//      PCache_FlushMiscPolys
//====================================================================================
BOOL PCache_FlushMiscPolys(void)
{
        int32                           i;
        Misc_Poly                       *pPoly;

        if (!MiscCache.NumPolys)
                return TRUE;

        if (!THandle_CheckCache())
                return GE_FALSE;

        // Set the render states
        if (AppInfo.CanDoMultiTexture)
        {
                AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_COLOROP,   D3DTOP_DISABLE );
                AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_ALPHAOP,   D3DTOP_DISABLE );
                D3DSetTexture(1, NULL);         // Reset texture stage 1
        }
        
          AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_TEXCOORDINDEX, 0);
          AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_COLORARG1, D3DTA_TEXTURE );
          AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_COLORARG2, D3DTA_DIFFUSE );
          AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_COLOROP,   D3DTOP_MODULATE );
          AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_ALPHAARG1, D3DTA_TEXTURE );
          AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_ALPHAARG2, D3DTA_DIFFUSE );
          AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_ALPHAOP,   D3DTOP_MODULATE);
          D3DBlendFunc (D3DBLEND_SRCALPHA, D3DBLEND_INVSRCALPHA);
          D3DBlendEnable(TRUE);

        // Sort the polys by handle
        SortMiscPolysByHandle();

        for (i=0; i< MiscCache.NumPolys; i++)
        {
                pPoly = MiscCache.SortedPolys[i];

                if (pPoly->Flags & DRV_RENDER_NO_ZMASK)         // We are assuming that this is not going to change all that much
                        D3DZEnable(FALSE);
                else
                        D3DZEnable(TRUE);

                if (pPoly->Flags & DRV_RENDER_NO_ZWRITE)        // We are assuming that this is not going to change all that much
                        D3DZWriteEnable(FALSE); 
                else
                        D3DZWriteEnable(TRUE);
                                                                          
                if (pPoly->Flags & DRV_RENDER_CLAMP_UV)
                        D3DTexWrap(0, FALSE);
                else
                        D3DTexWrap(0, TRUE);

                if (!SetupTexture(0, pPoly->THandle, pPoly->MipLevel))
                        return GE_FALSE;

                if ( (pPoly->Flags & DRV_RENDER_POLY_NO_FOG) && AppInfo.FogEnable) // poly fog
                        AppInfo.lpD3DDevice->SetRenderState(D3DRENDERSTATE_FOGENABLE , FALSE);

                D3DTexturedPoly(&MiscCache.Verts[pPoly->FirstVert], pPoly->NumVerts);

                if ( (pPoly->Flags & DRV_RENDER_POLY_NO_FOG) && AppInfo.FogEnable) // poly fog
                        AppInfo.lpD3DDevice->SetRenderState(D3DRENDERSTATE_FOGENABLE , TRUE);
        }

        // Turn z stuff back on...
        D3DZWriteEnable (TRUE);
        D3DZEnable(TRUE);
        
        MiscCache.NumPolys = 0;
        MiscCache.NumVerts = 0;

#ifdef SUPER_FLUSH
        AppInfo.lpD3DDevice->SetRenderState(D3DRENDERSTATE_FLUSHBATCH, 0);
        AppInfo.lpD3DDevice->EndScene();
        AppInfo.lpD3DDevice->BeginScene();
#endif

        return TRUE;
}

//====================================================================================
//      PCache_InsertMiscPoly
//====================================================================================
BOOL PCache_InsertMiscPoly(DRV_TLVertex *Verts, int32 NumVerts, geRDriver_THandle *THandle, uint32 Flags)
{
        int32                   Mip;
        geFloat                 ZRecip, u, v, ScaleU, ScaleV, InvScale;
        Misc_Poly               *pCachePoly;
        DRV_TLVertex    *pVerts;
        PCache_Vert             *pD3DVerts;
        int32                   i, SAlpha;

        if ((MiscCache.NumVerts + NumVerts) >= MAX_MISC_POLY_VERTS)
        {
                // If the cache is full, we must flush it before going on...
                PCache_FlushMiscPolys();
        }
        else if (MiscCache.NumPolys+1 >= MAX_MISC_POLYS)
        {
                // If the cache is full, we must flush it before going on...
                PCache_FlushMiscPolys();
        }

        Mip = GetMipLevel(Verts, NumVerts, (geFloat)THandle->Width, (geFloat)THandle->Height, THandle->NumMipLevels-1);

        // Store info about this poly in the cache
        pCachePoly = &MiscCache.Polys[MiscCache.NumPolys];

        pCachePoly->THandle = THandle;
        pCachePoly->Flags = Flags;
        pCachePoly->FirstVert = MiscCache.NumVerts;
        pCachePoly->NumVerts = NumVerts;
        pCachePoly->MipLevel = Mip;
        pCachePoly->SortKey = ((THandle - TextureHandles)<<4)+Mip;

        // Get scale value for vertices
        //TCache_GetUVInvScale(Bitmap, Mip, &InvScale);
        InvScale = 1.0f / (geFloat)((1<<THandle->Log));

        // Convert them to take account that the vertices are allready from 0 to 1
        ScaleU = (geFloat)THandle->Width * InvScale;
        ScaleV = (geFloat)THandle->Height * InvScale;

        // Precompute the alpha value...
        SAlpha = ((int32)Verts->a)<<24;

        // Get a pointer to the original polys verts
        pVerts = Verts;
        // Get a pointer into the world verts
        pD3DVerts = &MiscCache.Verts[MiscCache.NumVerts];

        for (i=0; i< NumVerts; i++)
        {
                ZRecip = 1/(pVerts->z);

                pD3DVerts->x = pVerts->x;
                pD3DVerts->y = pVerts->y;

                pD3DVerts->z = (1.0f - ZRecip);         // ZBUFFER
                pD3DVerts->rhw = ZRecip;
                
                u = pVerts->u * ScaleU;
                v = pVerts->v * ScaleV;

                pD3DVerts->uv[0].u = u;
                pD3DVerts->uv[0].v = v;

                pD3DVerts->color = SAlpha | ((int32)pVerts->r<<16) | ((int32)pVerts->g<<8) | (int32)pVerts->b;

                if (AppInfo.FogEnable && !(Flags & DRV_RENDER_POLY_NO_FOG) ) // poly fog
                {
                        DWORD   FogVal;
                        geFloat Val;

                        Val = pVerts->z;

                        if (Val > AppInfo.FogEnd)
                                Val = AppInfo.FogEnd;

                        FogVal = (DWORD)((AppInfo.FogEnd-Val)/(AppInfo.FogEnd-AppInfo.FogStart)*255.0f);
                
                        if (FogVal < 0)
                                FogVal = 0;
                        else if (FogVal > 255)
                                FogVal = 255;
                
                        pD3DVerts->specular = (FogVal<<24);             // Alpha component in specular is the fog value (0...255)
                }
                else
                        pD3DVerts->specular = 0;

                pVerts++;
                pD3DVerts++;
        }
        
        // Update globals about the misc poly cache
        MiscCache.NumVerts += NumVerts;
        MiscCache.NumPolys++;

        return TRUE;
}

//====================================================================================
//      **** LOCAL STATIC FUNCTIONS *****
//====================================================================================

//====================================================================================
//      World_PolyPrepVerts
//====================================================================================
geBoolean World_PolyPrepVerts(World_Poly *pPoly, int32 PrepMode, int32 Stage1, int32 Stage2)
{
        geFloat                 InvScale, u, v;
        PCache_TVert    *pTVerts;
        PCache_Vert             *pVerts;
        geFloat                 ShiftU, ShiftV, ScaleU, ScaleV;
        geFloat InvScale2, ShiftU2, ShiftV2;
        int32                   j;

        switch (PrepMode)
        {
                case PREP_WORLD_VERTS_NORMAL:
                {
                        pTVerts = &WorldCache.TVerts[pPoly->FirstVert];

                        ShiftU = pPoly->ShiftU;
                        ShiftV = pPoly->ShiftV;
                        ScaleU = pPoly->ScaleU;
                        ScaleV = pPoly->ScaleV;

                        // Get scale value for vertices
                        InvScale = 1.0f / (geFloat)((1<<pPoly->THandle->Log));

                        pVerts = &WorldCache.Verts[pPoly->FirstVert];
                        
                        for (j=0; j< pPoly->NumVerts; j++)
                        {
                                u = pTVerts->u*ScaleU+ShiftU;
                                v = pTVerts->v*ScaleV+ShiftV;

                                pVerts->uv[Stage1].u = u * InvScale;
                                pVerts->uv[Stage1].v = v * InvScale;

                                pVerts->color = pTVerts->Color;

                                pTVerts++;
                                pVerts++;
                        }

                        break;
                }

                case PREP_WORLD_VERTS_LMAP:
                {
                        if (!pPoly->LInfo)
                                return GE_TRUE;

                        ShiftU = (geFloat)-pPoly->LInfo->MinU + 8.0f;
                        ShiftV = (geFloat)-pPoly->LInfo->MinV + 8.0f;

                        // Get scale value for vertices
                        InvScale = 1.0f/(geFloat)((1<<pPoly->LInfo->THandle->Log)<<4);
                                
                        pTVerts = &WorldCache.TVerts[pPoly->FirstVert];
                        pVerts = &WorldCache.Verts[pPoly->FirstVert];

                        for (j=0; j< pPoly->NumVerts; j++)
                        {
                                u = pTVerts->u + ShiftU;
                                v = pTVerts->v + ShiftV;

                                pVerts->uv[Stage1].u = u * InvScale;
                                pVerts->uv[Stage1].v = v * InvScale;

                                pVerts->color = 0xffffffff;

                                pTVerts++;
                                pVerts++;
                        }
                        break;
                }

                case PREP_WORLD_VERTS_SINGLE_PASS:
                {

                        assert(pPoly->LInfo);

                        pTVerts = &WorldCache.TVerts[pPoly->FirstVert];

                        // Set up shifts and scaled for texture uv's
                        ShiftU = pPoly->ShiftU;
                        ShiftV = pPoly->ShiftV;
                        ScaleU = pPoly->ScaleU;
                        ScaleV = pPoly->ScaleV;

                        // Get scale value for vertices
                        InvScale = 1.0f / (geFloat)((1<<pPoly->THandle->Log));

                        // Set up shifts and scaled for lightmap uv's
                        ShiftU2 = (geFloat)-pPoly->LInfo->MinU + 8.0f;
                        ShiftV2 = (geFloat)-pPoly->LInfo->MinV + 8.0f;
                        InvScale2 = 1.0f/(geFloat)((1<<pPoly->LInfo->THandle->Log)<<4);

                        pVerts = &WorldCache.Verts[pPoly->FirstVert];

                        for (j=0; j< pPoly->NumVerts; j++)
                        {
                                u = pTVerts->u*ScaleU+ShiftU;
                                v = pTVerts->v*ScaleV+ShiftV;

                                pVerts->uv[Stage1].u = u * InvScale;
                                pVerts->uv[Stage1].v = v * InvScale;
                        
                                u = pTVerts->u + ShiftU2;
                                v = pTVerts->v + ShiftV2;

                                pVerts->uv[Stage2].u = u * InvScale2;
                                pVerts->uv[Stage2].v = v * InvScale2;

                                pVerts->color = pTVerts->Color;

                                pTVerts++;
                                pVerts++;
                        }

                        break;
                }

                default:
                        return FALSE;
        }

        return TRUE;
}

//====================================================================================
//====================================================================================
static int BitmapHandleComp(const void *a, const void *b)
{
        int32   Id1, Id2;

        Id1 = (*(World_Poly**)a)->SortKey;
        Id2 = (*(World_Poly**)b)->SortKey;

        if ( Id1 == Id2)
                return 0;

        if (Id1 < Id2)
                return -1;

        return 1;
}

//====================================================================================
//====================================================================================
static void SortWorldPolysByHandle(void)
{
        World_Poly      *pPoly;
        int32           i;

        pPoly = WorldCache.Polys;

        for (i=0; i<WorldCache.NumPolys; i++)
        {
                WorldCache.SortedPolys[i] = pPoly;
                pPoly++;
        }
        
        // Sort the polys
        qsort(&WorldCache.SortedPolys, WorldCache.NumPolys, sizeof(WorldCache.SortedPolys[0]), BitmapHandleComp);
}

#define TSTAGE_0                        0
#define TSTAGE_1                        1

D3DTEXTUREHANDLE                OldId;
LPDIRECT3DTEXTURE2              OldTexture[8];
//====================================================================================
//      RenderWorldPolys
//====================================================================================
static BOOL RenderWorldPolys(int32 RenderMode)
{
        World_Poly                      *pPoly;
        int32                           i;

        if(!AppInfo.RenderingIsOK)
        {
                return  TRUE;
        }
        switch (RenderMode)
        {       
                case RENDER_WORLD_POLYS_NORMAL:
                {
                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_TEXCOORDINDEX, 0 );

                        // Set the default state for the normal poly render mode for the world
                        D3DBlendEnable(TRUE);
                        D3DBlendFunc (D3DBLEND_SRCALPHA, D3DBLEND_INVSRCALPHA);
                        
                        // Get the first poly in the sorted list
                        SortWorldPolysByHandle();
                        
                        for (i=0; i< WorldCache.NumPolys; i++)
                        {
                                pPoly = WorldCache.SortedPolys[i];

                                if (pPoly->Flags & DRV_RENDER_CLAMP_UV)
                                        D3DTexWrap(0, FALSE);
                                else
                                        D3DTexWrap(0, TRUE);

                                if (!SetupTexture(0, pPoly->THandle, pPoly->MipLevel))
                                        return GE_FALSE;

                                World_PolyPrepVerts(pPoly, PREP_WORLD_VERTS_NORMAL, 0, 0);

                                D3DTexturedPoly(&WorldCache.Verts[pPoly->FirstVert], pPoly->NumVerts);
                        }
                        
                        break;
                }
                
                case RENDER_WORLD_POLYS_LMAP:
                {
                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_TEXCOORDINDEX, 0);

                        D3DTexWrap(0, FALSE);

                        D3DBlendEnable(TRUE);
                        D3DBlendFunc (D3DBLEND_DESTCOLOR, D3DBLEND_ZERO);

                        pPoly = WorldCache.Polys;
                        BOOL    Dynamic = 0;

                        for (i=0; i< WorldCache.NumPolys; i++, pPoly++)
                        {

                                if (!pPoly->LInfo)
                                        continue;

                                // Call the engine to set this sucker up, because it's visible...
                                D3DDRV.SetupLightmap(pPoly->LInfo, &Dynamic);

                                if (!SetupLMap(0, pPoly->LInfo, 0, Dynamic))
                                        return GE_FALSE;

                                World_PolyPrepVerts(pPoly, PREP_WORLD_VERTS_LMAP, 0, 0);

                                D3DTexturedPoly(&WorldCache.Verts[pPoly->FirstVert], pPoly->NumVerts);
                                
                                if (pPoly->LInfo->RGBLight[1])
                                {
                                        AppInfo.lpD3DDevice->SetRenderState(D3DRENDERSTATE_FOGENABLE, FALSE);

                                        D3DBlendFunc (D3DBLEND_ONE, D3DBLEND_ONE);                              // Change to a fog state

                                        // For some reason, some cards can't upload data to the same texture twice, and have it take.
                                        // So we force Fog maps to use a different slot than the lightmap was using...
                                        pPoly->LInfo->THandle->MipData[0].Slot = NULL;

                                        if (!SetupLMap(0, pPoly->LInfo, 1, 1))  // Dynamic is 1, because fog is always dynamic
                                                return GE_FALSE;

                                        D3DTexturedPoly(&WorldCache.Verts[pPoly->FirstVert], pPoly->NumVerts);
                
                                        D3DBlendFunc (D3DBLEND_DESTCOLOR, D3DBLEND_ZERO);               // Restore state

                                        if (AppInfo.FogEnable)
                                                AppInfo.lpD3DDevice->SetRenderState(D3DRENDERSTATE_FOGENABLE , TRUE);
                                }
                        }
                        break;
                }

                case RENDER_WORLD_POLYS_SINGLE_PASS:
                {
                        // Setup texture stage states
                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_TEXCOORDINDEX, 0 );
                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_COLORARG1, D3DTA_TEXTURE );
                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_COLORARG2, D3DTA_DIFFUSE );
                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_COLOROP,   D3DTOP_MODULATE );
                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_ALPHAARG1, D3DTA_TEXTURE );
                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_ALPHAARG2, D3DTA_DIFFUSE );
                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_ALPHAOP,   D3DTOP_MODULATE);
                                                                         
                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_TEXCOORDINDEX, 1 );
                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_COLORARG1, D3DTA_TEXTURE );
                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_COLORARG2, D3DTA_CURRENT ); 
                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_COLOROP,   D3DTOP_MODULATE );
                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_ALPHAARG1, D3DTA_DIFFUSE );
                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_ALPHAARG2, D3DTA_CURRENT );
                        //AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_ALPHAOP,   D3DTOP_SELECTARG2 );
                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_ALPHAOP,   D3DTOP_MODULATE );

                        // Setup frame buffer blend modes
                        D3DBlendEnable(TRUE);
                        D3DBlendFunc (D3DBLEND_SRCALPHA, D3DBLEND_INVSRCALPHA);

                        // Set the default state for the normal poly render mode for the world
                        D3DTexWrap(TSTAGE_0, TRUE);
                        D3DTexWrap(TSTAGE_1, FALSE);

                        // Sort the list for front back operation to get the least number of world texture misses
                        SortWorldPolysByHandle();
                        
                        // Reset non lightmaps faces to 0
                        WorldCache.NumPolys2 = 0;

                        for (i=0; i< WorldCache.NumPolys; i++)
                        {
                                BOOL    Dynamic = 0;

                                pPoly = WorldCache.SortedPolys[i];

                                if (!pPoly->LInfo)
                                {
                                        // Put gouraud only polys in a seperate list, and render last
                                        WorldCache.SortedPolys2[WorldCache.NumPolys2++] = pPoly;
                                        continue;
                                }

                                if (pPoly->Flags & DRV_RENDER_CLAMP_UV)
                                        D3DTexWrap(TSTAGE_0, FALSE);
                                else
                                        D3DTexWrap(TSTAGE_0, TRUE);

                                if (!SetupTexture(TSTAGE_0, pPoly->THandle, pPoly->MipLevel))
                                        return GE_FALSE;                                

                                // Call the engine to set this sucker up, because it's visible...
                                D3DDRV.SetupLightmap(pPoly->LInfo, &Dynamic);

                                if (!SetupLMap(TSTAGE_1, pPoly->LInfo, 0, Dynamic))
                                        return GE_FALSE;
                                        
                                // Prep the verts for a lightmap and texture map
                                World_PolyPrepVerts(pPoly, PREP_WORLD_VERTS_SINGLE_PASS, TSTAGE_0, TSTAGE_1);

                                if ( (pPoly->Flags & DRV_RENDER_POLY_NO_FOG) && AppInfo.FogEnable) // poly fog
                                                AppInfo.lpD3DDevice->SetRenderState(D3DRENDERSTATE_FOGENABLE , FALSE);

                                // Draw the texture
                                D3DTexturedPoly(&WorldCache.Verts[pPoly->FirstVert], pPoly->NumVerts);

                                if ( (pPoly->Flags & DRV_RENDER_POLY_NO_FOG) && AppInfo.FogEnable) // poly fog
                                                AppInfo.lpD3DDevice->SetRenderState(D3DRENDERSTATE_FOGENABLE , TRUE);

                                // Render any fog maps
                                if (pPoly->LInfo->RGBLight[1])
                                {
                                        D3DBlendFunc (D3DBLEND_ONE, D3DBLEND_ONE);                              // Change to a fog state

                                #if (TSTAGE_0 == 0)
                                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_COLOROP, D3DTOP_SELECTARG2);
                                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_ALPHAOP, D3DTOP_DISABLE);

                                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_COLOROP, D3DTOP_SELECTARG1);
                                #else
                                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_COLOROP, D3DTOP_DISABLE );
                                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_ALPHAOP, D3DTOP_DISABLE );
                                #endif

                                        // For some reason, some cards can't upload data to the same texture twice, and have it take.
                                        // So we force Fog maps to use a different slot other than what the lightmap was using...
                                        pPoly->LInfo->THandle->MipData[0].Slot = NULL;

                                        if (!SetupLMap(TSTAGE_1, pPoly->LInfo, 1, 1))   // Dynamic is 1, because fog is always dynamic
                                                return GE_FALSE;

                                        D3DTexturedPoly(&WorldCache.Verts[pPoly->FirstVert], pPoly->NumVerts);
        
                                        // Restore states to the last state before fag map
                                #if (TSTAGE_0 == 0)
                                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_COLOROP,   D3DTOP_MODULATE );
                                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_ALPHAOP,   D3DTOP_MODULATE);
        
                                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_COLOROP,   D3DTOP_MODULATE );
                                #else
                                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_COLOROP,   D3DTOP_MODULATE );
                                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_ALPHAOP,   D3DTOP_SELECTARG2 );
                                #endif

                                        D3DBlendFunc (D3DBLEND_SRCALPHA, D3DBLEND_INVSRCALPHA);
                                }
                                
                                
                        }
                        
                        // Setup for any non-lightmaped faces faces, turn tmu1 off
                #if (TSTAGE_0 == 0)
                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_COLOROP, D3DTOP_DISABLE);
                        AppInfo.lpD3DDevice->SetTextureStageState( 1, D3DTSS_ALPHAOP, D3DTOP_DISABLE);
                #else
                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_COLOROP, D3DTOP_SELECTARG2);
                        AppInfo.lpD3DDevice->SetTextureStageState( 0, D3DTSS_ALPHAOP, D3DTOP_SELECTARG2);
                #endif

                        // Render all the faces without lightmaps
                        for (i=0; i< WorldCache.NumPolys2; i++)
                        {
                                BOOL    Dynamic = 0;

                                pPoly = WorldCache.SortedPolys2[i];

                                if (pPoly->Flags & DRV_RENDER_CLAMP_UV)
                                        D3DTexWrap(TSTAGE_0, FALSE);
                                else
                                        D3DTexWrap(TSTAGE_0, TRUE);

                                if (!SetupTexture(TSTAGE_0, pPoly->THandle, pPoly->MipLevel))
                                        return GE_FALSE;                                

                                // Prep verts as if there was no lightmap
                                World_PolyPrepVerts(pPoly, PREP_WORLD_VERTS_NORMAL, TSTAGE_0, TSTAGE_1);

                                if ( (pPoly->Flags & DRV_RENDER_POLY_NO_FOG) && AppInfo.FogEnable) // poly fog
                                                AppInfo.lpD3DDevice->SetRenderState(D3DRENDERSTATE_FOGENABLE , FALSE);

                                // Draw the texture
                                D3DTexturedPoly(&WorldCache.Verts[pPoly->FirstVert], pPoly->NumVerts);

                                if ( (pPoly->Flags & DRV_RENDER_POLY_NO_FOG) && AppInfo.FogEnable) // poly fog
                                        AppInfo.lpD3DDevice->SetRenderState(D3DRENDERSTATE_FOGENABLE , TRUE);
                        }

                        break;                                           
                }

                default:
                        return FALSE;
        }


        return TRUE;
}

//====================================================================================
//      ClearWorldCache
//====================================================================================
static BOOL ClearWorldCache(void)
{
        WorldCache.NumPolys = 0;
        WorldCache.NumVerts = 0;

        return TRUE;
}

//====================================================================================
//====================================================================================
BOOL PCache_Reset(void)
{
        WorldCache.NumPolys = 0;
        WorldCache.NumVerts = 0;

        MiscCache.NumPolys = 0;
        MiscCache.NumVerts = 0;

        return TRUE;
}

//====================================================================================
//      GetMipLevel
//====================================================================================
static int32 GetMipLevel(DRV_TLVertex *Verts, int32 NumVerts, geFloat ScaleU, geFloat ScaleV, int32 MaxMipLevel)
{
        int32           Mip;

        if (MaxMipLevel == 0)
                return 0;

        //
        //      Get the MipLevel
        //
        {
                geFloat         du, dv, dx, dy, MipScale;

        #if 1           // WAY slower, but more accurate
                int32           i;

                MipScale = 999999.0f;

                geFloat                 MipScaleT;
                DRV_TLVertex    *pVert0, *pVert1;
                int32                   i2;

                for (i=0; i< NumVerts; i++)
                {

                        i2 = i+1;

                        if (i2 >= NumVerts)
                                i2=0;

                        pVert0 = &Verts[i];
                        pVert1 = &Verts[i2];

                        du = pVert1->u - pVert0->u;
                        dv = pVert1->v - pVert0->v;
                        dx = pVert1->x - pVert0->x;
                        dy = pVert1->y - pVert0->y;
                        
                        du *= ScaleU;
                        dv *= ScaleV;

                        MipScaleT = ((du*du)+(dv*dv)) / ((dx*dx)+(dy*dy));

                        if (MipScaleT < MipScale)
                                MipScale = MipScaleT;           // Record the best MipScale (the one closest to the the eye)
                }
        #else           // Faster, less accurate
                du = Verts[1].u - Verts[0].u;
                dv = Verts[1].v - Verts[0].v;
                dx = Verts[1].x - Verts[0].x;
                dy = Verts[1].y - Verts[0].y;

                du *= ScaleU;
                dv *= ScaleV;

                MipScale = ((du*du)+(dv*dv)) / ((dx*dx)+(dy*dy));
        #endif

        #if 0
                if (MipScale <= 5)              // 2, 6, 12
                        Mip = 0;
                else if (MipScale <= 20)
                        Mip = 1;
                else if (MipScale <= 45)
                        Mip = 2;
                else
                        Mip = 3;
        #else
                if (MipScale <= 4)              // 2, 6, 12
                        Mip = 0;
                else if (MipScale <= 15)
                        Mip = 1;
                else if (MipScale <= 40)
                        Mip = 2;
                else
                        Mip = 3;
        #endif
        }

        if (Mip > MaxMipLevel)
                Mip = MaxMipLevel;

        return Mip;
}

---