michael@0: //
michael@0: // Copyright (c) 2002-2012 The ANGLE Project Authors. All rights reserved.
michael@0: // Use of this source code is governed by a BSD-style license that can be
michael@0: // found in the LICENSE file.
michael@0: //
michael@0: 
michael@0: // generatemip.h: Defines the GenerateMip function, templated on the format
michael@0: // type of the image for which mip levels are being generated.
michael@0: 
michael@0: #ifndef LIBGLESV2_RENDERER_GENERATEMIP_H_
michael@0: #define LIBGLESV2_RENDERER_GENERATEMIP_H_
michael@0: 
michael@0: #include "libGLESv2/mathutil.h"
michael@0: 
michael@0: namespace rx
michael@0: {
michael@0: struct L8
michael@0: {
michael@0:     unsigned char L;
michael@0: 
michael@0:     static void average(L8 *dst, const L8 *src1, const L8 *src2)
michael@0:     {
michael@0:         dst->L = ((src1->L ^ src2->L) >> 1) + (src1->L & src2->L);
michael@0:     }
michael@0: };
michael@0: 
michael@0: typedef L8 R8; // R8 type is functionally equivalent for mip purposes
michael@0: typedef L8 A8; // A8 type is functionally equivalent for mip purposes
michael@0: 
michael@0: struct A8L8
michael@0: {
michael@0:     unsigned char L;
michael@0:     unsigned char A;
michael@0: 
michael@0:     static void average(A8L8 *dst, const A8L8 *src1, const A8L8 *src2)
michael@0:     {
michael@0:         *(unsigned short*)dst = (((*(unsigned short*)src1 ^ *(unsigned short*)src2) & 0xFEFE) >> 1) + (*(unsigned short*)src1 & *(unsigned short*)src2);
michael@0:     }
michael@0: };
michael@0: 
michael@0: typedef A8L8 R8G8; // R8G8 type is functionally equivalent for mip purposes
michael@0: 
michael@0: struct A8R8G8B8
michael@0: {
michael@0:     unsigned char B;
michael@0:     unsigned char G;
michael@0:     unsigned char R;
michael@0:     unsigned char A;
michael@0: 
michael@0:     static void average(A8R8G8B8 *dst, const A8R8G8B8 *src1, const A8R8G8B8 *src2)
michael@0:     {
michael@0:         *(unsigned int*)dst = (((*(unsigned int*)src1 ^ *(unsigned int*)src2) & 0xFEFEFEFE) >> 1) + (*(unsigned int*)src1 & *(unsigned int*)src2);
michael@0:     }
michael@0: };
michael@0: 
michael@0: typedef A8R8G8B8 R8G8B8A8; // R8G8B8A8 type is functionally equivalent for mip purposes
michael@0: 
michael@0: struct A16B16G16R16F
michael@0: {
michael@0:     unsigned short R;
michael@0:     unsigned short G;
michael@0:     unsigned short B;
michael@0:     unsigned short A;
michael@0: 
michael@0:     static void average(A16B16G16R16F *dst, const A16B16G16R16F *src1, const A16B16G16R16F *src2)
michael@0:     {
michael@0:         dst->R = gl::float32ToFloat16((gl::float16ToFloat32(src1->R) + gl::float16ToFloat32(src2->R)) * 0.5f);
michael@0:         dst->G = gl::float32ToFloat16((gl::float16ToFloat32(src1->G) + gl::float16ToFloat32(src2->G)) * 0.5f);
michael@0:         dst->B = gl::float32ToFloat16((gl::float16ToFloat32(src1->B) + gl::float16ToFloat32(src2->B)) * 0.5f);
michael@0:         dst->A = gl::float32ToFloat16((gl::float16ToFloat32(src1->A) + gl::float16ToFloat32(src2->A)) * 0.5f);
michael@0:     }
michael@0: };
michael@0: 
michael@0: struct R16F
michael@0: {
michael@0:     unsigned short R;
michael@0: 
michael@0:     static void average(R16F *dst, const R16F *src1, const R16F *src2)
michael@0:     {
michael@0:         dst->R = gl::float32ToFloat16((gl::float16ToFloat32(src1->R) + gl::float16ToFloat32(src2->R)) * 0.5f);
michael@0:     }
michael@0: };
michael@0: 
michael@0: struct R16G16F
michael@0: {
michael@0:     unsigned short R;
michael@0:     unsigned short G;
michael@0: 
michael@0:     static void average(R16G16F *dst, const R16G16F *src1, const R16G16F *src2)
michael@0:     {
michael@0:         dst->R = gl::float32ToFloat16((gl::float16ToFloat32(src1->R) + gl::float16ToFloat32(src2->R)) * 0.5f);
michael@0:         dst->G = gl::float32ToFloat16((gl::float16ToFloat32(src1->G) + gl::float16ToFloat32(src2->G)) * 0.5f);
michael@0:     }
michael@0: };
michael@0: 
michael@0: struct A32B32G32R32F
michael@0: {
michael@0:     float R;
michael@0:     float G;
michael@0:     float B;
michael@0:     float A;
michael@0: 
michael@0:     static void average(A32B32G32R32F *dst, const A32B32G32R32F *src1, const A32B32G32R32F *src2)
michael@0:     {
michael@0:         dst->R = (src1->R + src2->R) * 0.5f;
michael@0:         dst->G = (src1->G + src2->G) * 0.5f;
michael@0:         dst->B = (src1->B + src2->B) * 0.5f;
michael@0:         dst->A = (src1->A + src2->A) * 0.5f;
michael@0:     }
michael@0: };
michael@0: 
michael@0: struct R32F
michael@0: {
michael@0:     float R;
michael@0: 
michael@0:     static void average(R32F *dst, const R32F *src1, const R32F *src2)
michael@0:     {
michael@0:         dst->R = (src1->R + src2->R) * 0.5f;
michael@0:     }
michael@0: };
michael@0: 
michael@0: struct R32G32F
michael@0: {
michael@0:     float R;
michael@0:     float G;
michael@0: 
michael@0:     static void average(R32G32F *dst, const R32G32F *src1, const R32G32F *src2)
michael@0:     {
michael@0:         dst->R = (src1->R + src2->R) * 0.5f;
michael@0:         dst->G = (src1->G + src2->G) * 0.5f;
michael@0:     }
michael@0: };
michael@0: 
michael@0: struct R32G32B32F
michael@0: {
michael@0:     float R;
michael@0:     float G;
michael@0:     float B;
michael@0: 
michael@0:     static void average(R32G32B32F *dst, const R32G32B32F *src1, const R32G32B32F *src2)
michael@0:     {
michael@0:         dst->R = (src1->R + src2->R) * 0.5f;
michael@0:         dst->G = (src1->G + src2->G) * 0.5f;
michael@0:         dst->B = (src1->B + src2->B) * 0.5f;
michael@0:     }
michael@0: };
michael@0: 
michael@0: template <typename T>
michael@0: static void GenerateMip(unsigned int sourceWidth, unsigned int sourceHeight,
michael@0:                         const unsigned char *sourceData, int sourcePitch,
michael@0:                         unsigned char *destData, int destPitch)
michael@0: {
michael@0:     unsigned int mipWidth = std::max(1U, sourceWidth >> 1);
michael@0:     unsigned int mipHeight = std::max(1U, sourceHeight >> 1);
michael@0: 
michael@0:     if (sourceHeight == 1)
michael@0:     {
michael@0:         ASSERT(sourceWidth != 1);
michael@0: 
michael@0:         const T *src = (const T*)sourceData;
michael@0:         T *dst = (T*)destData;
michael@0: 
michael@0:         for (unsigned int x = 0; x < mipWidth; x++)
michael@0:         {
michael@0:             T::average(&dst[x], &src[x * 2], &src[x * 2 + 1]);
michael@0:         }
michael@0:     }
michael@0:     else if (sourceWidth == 1)
michael@0:     {
michael@0:         ASSERT(sourceHeight != 1);
michael@0: 
michael@0:         for (unsigned int y = 0; y < mipHeight; y++)
michael@0:         {
michael@0:             const T *src0 = (const T*)(sourceData + y * 2 * sourcePitch);
michael@0:             const T *src1 = (const T*)(sourceData + y * 2 * sourcePitch + sourcePitch);
michael@0:             T *dst = (T*)(destData + y * destPitch);
michael@0: 
michael@0:             T::average(dst, src0, src1);
michael@0:         }
michael@0:     }
michael@0:     else
michael@0:     {
michael@0:         for (unsigned int y = 0; y < mipHeight; y++)
michael@0:         {
michael@0:             const T *src0 = (const T*)(sourceData + y * 2 * sourcePitch);
michael@0:             const T *src1 = (const T*)(sourceData + y * 2 * sourcePitch + sourcePitch);
michael@0:             T *dst = (T*)(destData + y * destPitch);
michael@0: 
michael@0:             for (unsigned int x = 0; x < mipWidth; x++)
michael@0:             {
michael@0:                 T tmp0;
michael@0:                 T tmp1;
michael@0: 
michael@0:                 T::average(&tmp0, &src0[x * 2], &src0[x * 2 + 1]);
michael@0:                 T::average(&tmp1, &src1[x * 2], &src1[x * 2 + 1]);
michael@0:                 T::average(&dst[x], &tmp0, &tmp1);
michael@0:             }
michael@0:         }
michael@0:     }
michael@0: }
michael@0: }
michael@0: 
michael@0: #endif // LIBGLESV2_RENDERER_GENERATEMIP_H_