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117 lines
3.3 KiB
117 lines
3.3 KiB
//-----------------------------------------------------------------------------
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//
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// This file contains texture filtering functions.
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//
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// Copyright (C) Microsoft Corporation, 1997.
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//
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//-----------------------------------------------------------------------------
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#include "pch.cpp"
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#pragma hdrstop
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#include "ctexfilt.h"
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//-----------------------------------------------------------------------------
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//
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// TexFiltBilinear
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//
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// Given the basic bilinear equations
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//
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// A = C00 + U*(C10 - C00)
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// B = C01 + U*(C11 - C01)
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// C = A + V*(B-A)
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//
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// This routine is based on the re-arrangement of this equation into
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//
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// C = C00*(1-U-V+U*V) + C10*(U-U*V) + C10(V-U*V) + C11*(U*V)
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// or
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// C = C00*s1 + C10*s2 + C10*s3 + C11*s4
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//
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//-----------------------------------------------------------------------------
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void TexFiltBilinear(D3DCOLOR *pOut, INT32 iU, INT32 iV, UINT32 uTex00, UINT32 uTex10,
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UINT32 uTex01, UINT32 uTex11)
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{
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#define SIMPLE_BILINEAR 1
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#ifdef SIMPLE_BILINEAR
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INT32 r00, r01, r10, r11;
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INT32 g00, g01, g10, g11;
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INT32 b00, b01, b10, b11;
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INT32 a00, a01, a10, a11;
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r00 = RGBA_GETRED(uTex00);
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r01 = RGBA_GETRED(uTex01);
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r10 = RGBA_GETRED(uTex10);
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r11 = RGBA_GETRED(uTex11);
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g00 = RGBA_GETGREEN(uTex00);
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g01 = RGBA_GETGREEN(uTex01);
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g10 = RGBA_GETGREEN(uTex10);
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g11 = RGBA_GETGREEN(uTex11);
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b00 = RGBA_GETBLUE(uTex00);
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b01 = RGBA_GETBLUE(uTex01);
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b10 = RGBA_GETBLUE(uTex10);
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b11 = RGBA_GETBLUE(uTex11);
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a00 = RGBA_GETALPHA(uTex00);
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a01 = RGBA_GETALPHA(uTex01);
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a10 = RGBA_GETALPHA(uTex10);
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a11 = RGBA_GETALPHA(uTex11);
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r00 = r00 + ((iU*(r10 - r00)) >> 16);
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g00 = g00 + ((iU*(g10 - g00)) >> 16);
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b00 = b00 + ((iU*(b10 - b00)) >> 16);
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a00 = a00 + ((iU*(a10 - a00)) >> 16);
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r01 = r01 + ((iU*(r11 - r01)) >> 16);
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g01 = g01 + ((iU*(g11 - g01)) >> 16);
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b01 = b01 + ((iU*(b11 - b01)) >> 16);
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a01 = a01 + ((iU*(a11 - a01)) >> 16);
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r00 = r00 + ((iV*(r01 - r00)) >> 16);
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g00 = g00 + ((iV*(g01 - g00)) >> 16);
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b00 = b00 + ((iV*(b01 - b00)) >> 16);
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a00 = a00 + ((iV*(a01 - a00)) >> 16);
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#else
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// another potential implementation
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INT32 s1, s2, s3, s4;
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s4 = (iU * iV)>>16; // (0.16 * 0.16) >> 16 = 0.16
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s3 = iV - s4;
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s2 = iU - s4;
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s1 = 0x10000 - iV - s2;
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INT32 r00, r01, r10, r11;
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INT32 g00, g01, g10, g11;
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INT32 b00, b01, b10, b11;
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INT32 a00, a01, a10, a11;
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r00 = RGBA_GETRED(uTex00);
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r01 = RGBA_GETRED(uTex01);
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r10 = RGBA_GETRED(uTex10);
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r11 = RGBA_GETRED(uTex11);
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g00 = RGBA_GETGREEN(uTex00);
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g01 = RGBA_GETGREEN(uTex01);
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g10 = RGBA_GETGREEN(uTex10);
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g11 = RGBA_GETGREEN(uTex11);
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b00 = RGBA_GETBLUE(uTex00);
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b01 = RGBA_GETBLUE(uTex01);
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b10 = RGBA_GETBLUE(uTex10);
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b11 = RGBA_GETBLUE(uTex11);
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a00 = RGBA_GETALPHA(uTex00);
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a01 = RGBA_GETALPHA(uTex01);
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a10 = RGBA_GETALPHA(uTex10);
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a11 = RGBA_GETALPHA(uTex11);
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// 8.0 * 0.16 == 8.16 >> 16 == 8.0
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r00 = (r00*s1 + r10*s2 + r01*s3 + r11*s4)>>16;
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g00 = (g00*s1 + g10*s2 + g01*s3 + g11*s4)>>16;
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b00 = (b00*s1 + b10*s2 + b01*s3 + b11*s4)>>16;
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a00 = (a00*s1 + a10*s2 + a01*s3 + a11*s4)>>16;
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#endif
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*pOut = RGBA_MAKE(r00, g00, b00, a00);
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}
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