s_blend.c

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/*
 * Mesa 3-D graphics library
 * Version:  6.3
 *
 * Copyright (C) 1999-2005  Brian Paul   All Rights Reserved.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

/*
 * Regarding GL_NV_blend_square:
 *
 * Portions of this software may use or implement intellectual
 * property owned and licensed by NVIDIA Corporation. NVIDIA disclaims
 * any and all warranties with respect to such intellectual property,
 * including any use thereof or modifications thereto.
 */


#include "glheader.h"
#include "context.h"
#include "colormac.h"
#include "macros.h"

#include "s_blend.h"
#include "s_context.h"
#include "s_span.h"


#if defined(USE_MMX_ASM)
#include "x86/mmx.h"
#include "x86/common_x86_asm.h"
#define _BLENDAPI _ASMAPI
#else
#define _BLENDAPI
#endif


/*
 * Special case for glBlendFunc(GL_ZERO, GL_ONE)
 */
static void _BLENDAPI
blend_noop( GLcontext *ctx, GLuint n, const GLubyte mask[],
            GLchan rgba[][4], CONST GLchan dest[][4] )
{
   GLuint i;
   ASSERT(ctx->Color.BlendEquationRGB==GL_FUNC_ADD);
   ASSERT(ctx->Color.BlendEquationA==GL_FUNC_ADD);
   ASSERT(ctx->Color.BlendSrcRGB==GL_ZERO);
   ASSERT(ctx->Color.BlendDstRGB==GL_ONE);
   (void) ctx;

   for (i = 0; i < n; i++) {
      if (mask[i]) {
         COPY_CHAN4( rgba[i], dest[i] );
      }
   }
}


/*
 * Special case for glBlendFunc(GL_ONE, GL_ZERO)
 */
static void _BLENDAPI
blend_replace( GLcontext *ctx, GLuint n, const GLubyte mask[],
               GLchan rgba[][4], CONST GLchan dest[][4] )
{
   ASSERT(ctx->Color.BlendEquationRGB==GL_FUNC_ADD);
   ASSERT(ctx->Color.BlendEquationA==GL_FUNC_ADD);
   ASSERT(ctx->Color.BlendSrcRGB==GL_ONE);
   ASSERT(ctx->Color.BlendDstRGB==GL_ZERO);
   (void) ctx;
   (void) n;
   (void) mask;
   (void) rgba;
   (void) dest;
}


/*
 * Common transparency blending mode.
 */
static void _BLENDAPI
blend_transparency( GLcontext *ctx, GLuint n, const GLubyte mask[],
                    GLchan rgba[][4], CONST GLchan dest[][4] )
{
   GLuint i;
   ASSERT(ctx->Color.BlendEquationRGB==GL_FUNC_ADD);
   ASSERT(ctx->Color.BlendEquationA==GL_FUNC_ADD);
   ASSERT(ctx->Color.BlendSrcRGB==GL_SRC_ALPHA);
   ASSERT(ctx->Color.BlendDstRGB==GL_ONE_MINUS_SRC_ALPHA);
   (void) ctx;

   for (i=0;i<n;i++) {
      if (mask[i]) {
         const GLchan t = rgba[i][ACOMP];  /* t in [0, CHAN_MAX] */
         if (t == 0) {
            /* 0% alpha */
            rgba[i][RCOMP] = dest[i][RCOMP];
            rgba[i][GCOMP] = dest[i][GCOMP];
            rgba[i][BCOMP] = dest[i][BCOMP];
            rgba[i][ACOMP] = dest[i][ACOMP];
         }
         else if (t == CHAN_MAX) {
            /* 100% alpha, no-op */
         }
         else {
#if 0
            /* This is pretty close, but Glean complains */
            const GLint s = CHAN_MAX - t;
            const GLint r = (rgba[i][RCOMP] * t + dest[i][RCOMP] * s + 1) >> 8;
            const GLint g = (rgba[i][GCOMP] * t + dest[i][GCOMP] * s + 1) >> 8;
            const GLint b = (rgba[i][BCOMP] * t + dest[i][BCOMP] * s + 1) >> 8;
            const GLint a = (rgba[i][ACOMP] * t + dest[i][ACOMP] * s + 1) >> 8;
#elif 0
            /* This is slower but satisfies Glean */
            const GLint s = CHAN_MAX - t;
            const GLint r = (rgba[i][RCOMP] * t + dest[i][RCOMP] * s) / 255;
            const GLint g = (rgba[i][GCOMP] * t + dest[i][GCOMP] * s) / 255;
            const GLint b = (rgba[i][BCOMP] * t + dest[i][BCOMP] * s) / 255;
            const GLint a = (rgba[i][ACOMP] * t + dest[i][ACOMP] * s) / 255;
#else
#if CHAN_BITS == 8
            /* This satisfies Glean and should be reasonably fast */
            /* Contributed by Nathan Hand */
#if 0
#define DIV255(X)  (((X) << 8) + (X) + 256) >> 16
#else
	    GLint temp;
#define DIV255(X)  (temp = (X), ((temp << 8) + temp + 256) >> 16)
#endif
            const GLint r = DIV255((rgba[i][RCOMP] - dest[i][RCOMP]) * t) + dest[i][RCOMP];
            const GLint g = DIV255((rgba[i][GCOMP] - dest[i][GCOMP]) * t) + dest[i][GCOMP];
            const GLint b = DIV255((rgba[i][BCOMP] - dest[i][BCOMP]) * t) + dest[i][BCOMP];
            const GLint a = DIV255((rgba[i][ACOMP] - dest[i][ACOMP]) * t) + dest[i][ACOMP]; 

#undef DIV255
#elif CHAN_BITS == 16
            const GLfloat tt = (GLfloat) t / CHAN_MAXF;
            const GLint r = (GLint) ((rgba[i][RCOMP] - dest[i][RCOMP]) * tt + dest[i][RCOMP]);
            const GLint g = (GLint) ((rgba[i][GCOMP] - dest[i][GCOMP]) * tt + dest[i][GCOMP]);
            const GLint b = (GLint) ((rgba[i][BCOMP] - dest[i][BCOMP]) * tt + dest[i][BCOMP]);
            const GLint a = (GLint) ((rgba[i][ACOMP] - dest[i][ACOMP]) * tt + dest[i][ACOMP]);
#else /* CHAN_BITS == 32 */
            const GLfloat tt = (GLfloat) t / CHAN_MAXF;
            const GLfloat r = (rgba[i][RCOMP] - dest[i][RCOMP]) * tt + dest[i][RCOMP];
            const GLfloat g = (rgba[i][GCOMP] - dest[i][GCOMP]) * tt + dest[i][GCOMP];
            const GLfloat b = (rgba[i][BCOMP] - dest[i][BCOMP]) * tt + dest[i][BCOMP];
            const GLfloat a = CLAMP( rgba[i][ACOMP], 0.0F, CHAN_MAXF ) * t +
                              CLAMP( dest[i][ACOMP], 0.0F, CHAN_MAXF ) * (1.0F - t);
#endif
#endif
            ASSERT(r <= CHAN_MAX);
            ASSERT(g <= CHAN_MAX);
            ASSERT(b <= CHAN_MAX);
            ASSERT(a <= CHAN_MAX);
            rgba[i][RCOMP] = (GLchan) r;
            rgba[i][GCOMP] = (GLchan) g;
            rgba[i][BCOMP] = (GLchan) b;
            rgba[i][ACOMP] = (GLchan) a;
         }
      }
   }
}



/*
 * Add src and dest.
 */
static void _BLENDAPI
blend_add( GLcontext *ctx, GLuint n, const GLubyte mask[],
           GLchan rgba[][4], CONST GLchan dest[][4] )
{
   GLuint i;
   ASSERT(ctx->Color.BlendEquationRGB==GL_FUNC_ADD);
   ASSERT(ctx->Color.BlendEquationA==GL_FUNC_ADD);
   ASSERT(ctx->Color.BlendSrcRGB==GL_ONE);
   ASSERT(ctx->Color.BlendDstRGB==GL_ONE);
   (void) ctx;

   for (i=0;i<n;i++) {
      if (mask[i]) {
#if CHAN_TYPE == GL_FLOAT
         /* don't RGB clamp to max */
         GLfloat a = CLAMP(rgba[i][ACOMP], 0.0F, CHAN_MAXF) + dest[i][ACOMP];
         rgba[i][RCOMP] += dest[i][RCOMP];
         rgba[i][GCOMP] += dest[i][GCOMP];
         rgba[i][BCOMP] += dest[i][BCOMP];
         rgba[i][ACOMP] = (GLchan) MIN2( a, CHAN_MAXF );
#else
         GLint r = rgba[i][RCOMP] + dest[i][RCOMP];
         GLint g = rgba[i][GCOMP] + dest[i][GCOMP];
         GLint b = rgba[i][BCOMP] + dest[i][BCOMP];
         GLint a = rgba[i][ACOMP] + dest[i][ACOMP];
         rgba[i][RCOMP] = (GLchan) MIN2( r, CHAN_MAX );
         rgba[i][GCOMP] = (GLchan) MIN2( g, CHAN_MAX );
         rgba[i][BCOMP] = (GLchan) MIN2( b, CHAN_MAX );
         rgba[i][ACOMP] = (GLchan) MIN2( a, CHAN_MAX );
#endif
      }
   }
}



/*
 * Blend min function  (for GL_EXT_blend_minmax)
 */
static void _BLENDAPI
blend_min( GLcontext *ctx, GLuint n, const GLubyte mask[],
           GLchan rgba[][4], CONST GLchan dest[][4] )
{
   GLuint i;
   ASSERT(ctx->Color.BlendEquationRGB==GL_MIN);
   ASSERT(ctx->Color.BlendEquationA==GL_MIN);
   (void) ctx;

   for (i=0;i<n;i++) {
      if (mask[i]) {
         rgba[i][RCOMP] = (GLchan) MIN2( rgba[i][RCOMP], dest[i][RCOMP] );
         rgba[i][GCOMP] = (GLchan) MIN2( rgba[i][GCOMP], dest[i][GCOMP] );
         rgba[i][BCOMP] = (GLchan) MIN2( rgba[i][BCOMP], dest[i][BCOMP] );
#if CHAN_TYPE == GL_FLOAT
         rgba[i][ACOMP] = (GLchan) MIN2(CLAMP(rgba[i][ACOMP], 0.0F, CHAN_MAXF),
                                        dest[i][ACOMP]);
#else
         rgba[i][ACOMP] = (GLchan) MIN2( rgba[i][ACOMP], dest[i][ACOMP] );
#endif
      }
   }
}



/*
 * Blend max function  (for GL_EXT_blend_minmax)
 */
static void _BLENDAPI
blend_max( GLcontext *ctx, GLuint n, const GLubyte mask[],
           GLchan rgba[][4], CONST GLchan dest[][4] )
{
   GLuint i;
   ASSERT(ctx->Color.BlendEquationRGB==GL_MAX);
   ASSERT(ctx->Color.BlendEquationA==GL_MAX);
   (void) ctx;

   for (i=0;i<n;i++) {
      if (mask[i]) {
         rgba[i][RCOMP] = (GLchan) MAX2( rgba[i][RCOMP], dest[i][RCOMP] );
         rgba[i][GCOMP] = (GLchan) MAX2( rgba[i][GCOMP], dest[i][GCOMP] );
         rgba[i][BCOMP] = (GLchan) MAX2( rgba[i][BCOMP], dest[i][BCOMP] );
#if CHAN_TYPE == GL_FLOAT
         rgba[i][ACOMP] = (GLchan) MAX2(CLAMP(rgba[i][ACOMP], 0.0F, CHAN_MAXF),
                                        dest[i][ACOMP]);
#else
         rgba[i][ACOMP] = (GLchan) MAX2( rgba[i][ACOMP], dest[i][ACOMP] );
#endif
      }
   }
}



/*
 * Modulate:  result = src * dest
 */
static void _BLENDAPI
blend_modulate( GLcontext *ctx, GLuint n, const GLubyte mask[],
                GLchan rgba[][4], CONST GLchan dest[][4] )
{
   GLuint i;
   (void) ctx;

   for (i=0;i<n;i++) {
      if (mask[i]) {
#if CHAN_TYPE == GL_FLOAT
         rgba[i][RCOMP] = rgba[i][RCOMP] * dest[i][RCOMP];
         rgba[i][GCOMP] = rgba[i][GCOMP] * dest[i][GCOMP];
         rgba[i][BCOMP] = rgba[i][BCOMP] * dest[i][BCOMP];
         rgba[i][ACOMP] = rgba[i][ACOMP] * dest[i][ACOMP];
#elif CHAN_TYPE == GL_UNSIGNED_SHORT
         GLint r = (rgba[i][RCOMP] * dest[i][RCOMP] + 65535) >> 16;
         GLint g = (rgba[i][GCOMP] * dest[i][GCOMP] + 65535) >> 16;
         GLint b = (rgba[i][BCOMP] * dest[i][BCOMP] + 65535) >> 16;
         GLint a = (rgba[i][ACOMP] * dest[i][ACOMP] + 65535) >> 16;
         rgba[i][RCOMP] = (GLchan) r;
         rgba[i][GCOMP] = (GLchan) g;
         rgba[i][BCOMP] = (GLchan) b;
         rgba[i][ACOMP] = (GLchan) a;
#else
         GLint r = (rgba[i][RCOMP] * dest[i][RCOMP] + 255) >> 8;
         GLint g = (rgba[i][GCOMP] * dest[i][GCOMP] + 255) >> 8;
         GLint b = (rgba[i][BCOMP] * dest[i][BCOMP] + 255) >> 8;
         GLint a = (rgba[i][ACOMP] * dest[i][ACOMP] + 255) >> 8;
         rgba[i][RCOMP] = (GLchan) r;
         rgba[i][GCOMP] = (GLchan) g;
         rgba[i][BCOMP] = (GLchan) b;
         rgba[i][ACOMP] = (GLchan) a;
#endif
      }
   }
}



/*
 * General case blend pixels.
 * Input:  n - number of pixels
 *         mask - the usual write mask
 * In/Out:  rgba - the incoming and modified pixels
 * Input:  dest - the pixels from the dest color buffer
 */
static void _BLENDAPI
blend_general( GLcontext *ctx, GLuint n, const GLubyte mask[],
               GLchan rgba[][4], CONST GLchan dest[][4] )
{
   const GLfloat rscale = 1.0F / CHAN_MAXF;
   const GLfloat gscale = 1.0F / CHAN_MAXF;
   const GLfloat bscale = 1.0F / CHAN_MAXF;
   const GLfloat ascale = 1.0F / CHAN_MAXF;
   GLuint i;

   for (i=0;i<n;i++) {
      if (mask[i]) {
#if CHAN_TYPE == GL_FLOAT
         GLfloat Rs, Gs, Bs, As;  /* Source colors */
         GLfloat Rd, Gd, Bd, Ad;  /* Dest colors */
#else
         GLint Rs, Gs, Bs, As;  /* Source colors */
         GLint Rd, Gd, Bd, Ad;  /* Dest colors */
#endif
         GLfloat sR, sG, sB, sA;  /* Source scaling */
         GLfloat dR, dG, dB, dA;  /* Dest scaling */
         GLfloat r, g, b, a;      /* result color */

         /* Incoming/source Color */
         Rs = rgba[i][RCOMP];
         Gs = rgba[i][GCOMP];
         Bs = rgba[i][BCOMP];
         As = rgba[i][ACOMP];
#if CHAN_TYPE == GL_FLOAT
         /* clamp */
         Rs = MIN2(Rs, CHAN_MAXF);
         Gs = MIN2(Gs, CHAN_MAXF);
         Bs = MIN2(Bs, CHAN_MAXF);
         As = MIN2(As, CHAN_MAXF);
#endif

         /* Frame buffer/dest color */
         Rd = dest[i][RCOMP];
         Gd = dest[i][GCOMP];
         Bd = dest[i][BCOMP];
         Ad = dest[i][ACOMP];
#if CHAN_TYPE == GL_FLOAT
         /* clamp */
         Rd = MIN2(Rd, CHAN_MAXF);
         Gd = MIN2(Gd, CHAN_MAXF);
         Bd = MIN2(Bd, CHAN_MAXF);
         Ad = MIN2(Ad, CHAN_MAXF);
#endif

         /* Source RGB factor */
         switch (ctx->Color.BlendSrcRGB) {
            case GL_ZERO:
               sR = sG = sB = 0.0F;
               break;
            case GL_ONE:
               sR = sG = sB = 1.0F;
               break;
            case GL_DST_COLOR:
               sR = (GLfloat) Rd * rscale;
               sG = (GLfloat) Gd * gscale;
               sB = (GLfloat) Bd * bscale;
               break;
            case GL_ONE_MINUS_DST_COLOR:
               sR = 1.0F - (GLfloat) Rd * rscale;
               sG = 1.0F - (GLfloat) Gd * gscale;
               sB = 1.0F - (GLfloat) Bd * bscale;
               break;
            case GL_SRC_ALPHA:
               sR = sG = sB = (GLfloat) As * ascale;
               break;
            case GL_ONE_MINUS_SRC_ALPHA:
               sR = sG = sB = 1.0F - (GLfloat) As * ascale;
               break;
            case GL_DST_ALPHA:
               sR = sG = sB = (GLfloat) Ad * ascale;
               break;
            case GL_ONE_MINUS_DST_ALPHA:
               sR = sG = sB = 1.0F - (GLfloat) Ad * ascale;
               break;
            case GL_SRC_ALPHA_SATURATE:
               if (As < CHAN_MAX - Ad) {
                  sR = sG = sB = (GLfloat) As * ascale;
               }
               else {
                  sR = sG = sB = 1.0F - (GLfloat) Ad * ascale;
               }
               break;
            case GL_CONSTANT_COLOR:
               sR = ctx->Color.BlendColor[0];
               sG = ctx->Color.BlendColor[1];
               sB = ctx->Color.BlendColor[2];
               break;
            case GL_ONE_MINUS_CONSTANT_COLOR:
               sR = 1.0F - ctx->Color.BlendColor[0];
               sG = 1.0F - ctx->Color.BlendColor[1];
               sB = 1.0F - ctx->Color.BlendColor[2];
               break;
            case GL_CONSTANT_ALPHA:
               sR = sG = sB = ctx->Color.BlendColor[3];
               break;
            case GL_ONE_MINUS_CONSTANT_ALPHA:
               sR = sG = sB = 1.0F - ctx->Color.BlendColor[3];
               break;
            case GL_SRC_COLOR: /* GL_NV_blend_square */
               sR = (GLfloat) Rs * rscale;
               sG = (GLfloat) Gs * gscale;
               sB = (GLfloat) Bs * bscale;
               break;
            case GL_ONE_MINUS_SRC_COLOR: /* GL_NV_blend_square */