--- /dev/null
+/* $Id: blend.c,v 1.10 1998/01/27 03:42:40 brianp Exp $ */
+
+/*
+ * Mesa 3-D graphics library
+ * Version: 2.6
+ * Copyright (C) 1995-1997 Brian Paul
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ * License along with this library; if not, write to the Free
+ * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+
+/*
+ * $Log: blend.c,v $
+ * Revision 1.10 1998/01/27 03:42:40 brianp
+ * optimized more blending modes (Kai Schuetz)
+ *
+ * Revision 1.9 1997/07/24 01:24:45 brianp
+ * changed precompiled header symbol from PCH to PC_HEADER
+ *
+ * Revision 1.8 1997/05/28 03:23:48 brianp
+ * added precompiled header (PCH) support
+ *
+ * Revision 1.7 1997/04/20 19:51:57 brianp
+ * replaced abort() with gl_problem()
+ *
+ * Revision 1.6 1997/02/15 18:27:56 brianp
+ * fixed a few error messages
+ *
+ * Revision 1.5 1997/01/28 22:17:19 brianp
+ * moved logic op blending into logic.c
+ *
+ * Revision 1.4 1997/01/04 00:13:11 brianp
+ * was using ! instead of ~ to invert pixel bits (ugh!)
+ *
+ * Revision 1.3 1996/09/19 00:53:31 brianp
+ * added missing returns after some gl_error() calls
+ *
+ * Revision 1.2 1996/09/15 14:18:10 brianp
+ * now use GLframebuffer and GLvisual
+ *
+ * Revision 1.1 1996/09/13 01:38:16 brianp
+ * Initial revision
+ *
+ */
+
+
+#ifdef PC_HEADER
+#include "all.h"
+#else
+#include <assert.h>
+#include <stdlib.h>
+#include "alphabuf.h"
+#include "blend.h"
+#include "context.h"
+#include "dlist.h"
+#include "macros.h"
+#include "pb.h"
+#include "span.h"
+#include "types.h"
+#endif
+
+
+
+void gl_BlendFunc( GLcontext* ctx, GLenum sfactor, GLenum dfactor )
+{
+ if (INSIDE_BEGIN_END(ctx)) {
+ gl_error( ctx, GL_INVALID_OPERATION, "glBlendFunc" );
+ return;
+ }
+
+ switch (sfactor) {
+ case GL_ZERO:
+ case GL_ONE:
+ case GL_DST_COLOR:
+ case GL_ONE_MINUS_DST_COLOR:
+ case GL_SRC_ALPHA:
+ case GL_ONE_MINUS_SRC_ALPHA:
+ case GL_DST_ALPHA:
+ case GL_ONE_MINUS_DST_ALPHA:
+ case GL_SRC_ALPHA_SATURATE:
+ ctx->Color.BlendSrc = sfactor;
+ break;
+ default:
+ gl_error( ctx, GL_INVALID_ENUM, "glBlendFunc(sfactor)" );
+ return;
+ }
+
+ switch (dfactor) {
+ case GL_ZERO:
+ case GL_ONE:
+ case GL_SRC_COLOR:
+ case GL_ONE_MINUS_SRC_COLOR:
+ case GL_SRC_ALPHA:
+ case GL_ONE_MINUS_SRC_ALPHA:
+ case GL_DST_ALPHA:
+ case GL_ONE_MINUS_DST_ALPHA:
+ ctx->Color.BlendDst = dfactor;
+ break;
+ default:
+ gl_error( ctx, GL_INVALID_ENUM, "glBlendFunc(dfactor)" );
+ }
+
+ ctx->NewState |= NEW_RASTER_OPS;
+}
+
+
+
+/*
+ * Do the real work of gl_blend_span() and gl_blend_pixels().
+ * Input: n - number of pixels
+ * mask - the usual write mask
+ * In/Out: red, green, blue, alpha - the incoming and modified pixels
+ * Input: rdest, gdest, bdest, adest - the pixels from the dest color buffer
+ */
+static void do_blend( GLcontext* ctx, GLuint n, const GLubyte mask[],
+ GLubyte red[], GLubyte green[],
+ GLubyte blue[], GLubyte alpha[],
+ const GLubyte rdest[], const GLubyte gdest[],
+ const GLubyte bdest[], const GLubyte adest[] )
+{
+ GLuint i;
+
+ if (ctx->Color.BlendSrc==GL_SRC_ALPHA
+ && ctx->Color.BlendDst==GL_ONE_MINUS_SRC_ALPHA) {
+ /* Alpha blending */
+ GLfloat ascale = 256.0f * ctx->Visual->InvAlphaScale;
+ GLint rmax = (GLint) ctx->Visual->RedScale;
+ GLint gmax = (GLint) ctx->Visual->GreenScale;
+ GLint bmax = (GLint) ctx->Visual->BlueScale;
+ GLint amax = (GLint) ctx->Visual->AlphaScale;
+ for (i=0;i<n;i++) {
+ if (mask[i]) {
+ GLint r, g, b, a;
+ GLint t = (GLint) ( alpha[i] * ascale ); /* t in [0,256] */
+ GLint s = 256 - t;
+ r = (red[i] * t + rdest[i] * s) >> 8;
+ g = (green[i] * t + gdest[i] * s) >> 8;
+ b = (blue[i] * t + bdest[i] * s) >> 8;
+ a = (alpha[i] * t + adest[i] * s) >> 8;
+
+ /* kai: I think the following clamping is not needed: */
+
+ red[i] = MIN2( r, rmax );
+ green[i] = MIN2( g, gmax );
+ blue[i] = MIN2( b, bmax );
+ alpha[i] = MIN2( a, amax );
+ }
+ }
+ }
+ else {
+
+ /* clipped sum */
+ if (ctx->Color.BlendSrc==GL_ONE
+ && ctx->Color.BlendDst==GL_ONE) {
+ GLint rmax = (GLint) ctx->Visual->RedScale;
+ GLint gmax = (GLint) ctx->Visual->GreenScale;
+ GLint bmax = (GLint) ctx->Visual->BlueScale;
+ GLint amax = (GLint) ctx->Visual->AlphaScale;
+ for (i=0; i < n; i++) {
+ if (mask[i]) {
+ red[i] = MIN2(rmax, red[i] + rdest[i]);
+ green[i] = MIN2(gmax, green[i] + gdest[i]);
+ blue[i] = MIN2(bmax, blue[i] + bdest[i]);
+ alpha[i] = MIN2(amax, alpha[i] + adest[i]);
+ }
+ }
+ }
+
+ /* modulation */
+ else if ((ctx->Color.BlendSrc==GL_ZERO &&
+ ctx->Color.BlendDst==GL_SRC_COLOR)
+ ||
+ (ctx->Color.BlendSrc==GL_DST_COLOR &&
+ ctx->Color.BlendDst==GL_ZERO)) {
+ if (ctx->Visual->EightBitColor) {
+ for (i=0; i < n; i++) {
+ if (mask[i]) {
+ red[i] = (red[i] * rdest[i]) / 255;
+ green[i] = (green[i] * gdest[i]) / 255;
+ blue[i] = (blue[i] * bdest[i]) / 255;
+ alpha[i] = (alpha[i] * adest[i]) / 255;
+ }
+ }
+ }
+ else {
+ GLint rmax = (GLint) ctx->Visual->RedScale;
+ GLint gmax = (GLint) ctx->Visual->GreenScale;
+ GLint bmax = (GLint) ctx->Visual->BlueScale;
+ GLint amax = (GLint) ctx->Visual->AlphaScale;
+ for (i=0; i < n; i++) {
+ if (mask[i]) {
+ red[i] = (red[i] * rdest[i]) / rmax;
+ green[i] = (green[i] * gdest[i]) / gmax;
+ blue[i] = (blue[i] * bdest[i]) / bmax;
+ alpha[i] = (alpha[i] * adest[i]) / amax;
+ }
+ }
+ }
+ }else{
+
+ /* General cases: */
+
+ if (ctx->Visual->EightBitColor) {
+ for (i=0;i<n;i++) {
+ if (mask[i]) {
+ GLint Rs, Gs, Bs, As; /* Source colors */
+ GLint Rd, Gd, Bd, Ad; /* Dest colors */
+ GLint Rss, Gss, Bss, Ass; /* Source colors scaled */
+ GLint Rds, Gds, Bds, Ads; /* Dest colors scaled */
+
+ /* Source Color */
+ Rs = red[i];
+ Gs = green[i];
+ Bs = blue[i];
+ As = alpha[i];
+
+ /* Frame buffer color */
+ Rd = rdest[i];
+ Gd = gdest[i];
+ Bd = bdest[i];
+ Ad = adest[i];
+
+ /* Source scaling */
+ switch (ctx->Color.BlendSrc) {
+ case GL_ZERO:
+ Rss = Gss = Bss = Ass = 0;
+ break;
+ case GL_ONE:
+ Rss = Rs * 255;
+ Gss = Gs * 255;
+ Bss = Bs * 255;
+ Ass = As * 255;
+ break;
+ case GL_DST_COLOR:
+ Rss = Rs * Rd;
+ Gss = Gs * Gd;
+ Bss = Bs * Bd;
+ Ass = As * Ad;
+ break;
+ case GL_ONE_MINUS_DST_COLOR:
+ Rss = Rs * (255 - Rd);
+ Gss = Gs * (255 - Gd);
+ Bss = Bs * (255 - Bd);
+ Ass = As * (255 - Ad);
+ break;
+ case GL_SRC_ALPHA:
+ Rss = Rs * As;
+ Gss = Gs * As;
+ Bss = Bs * As;
+ Ass = As * As;
+ break;
+ case GL_ONE_MINUS_SRC_ALPHA:
+ Rss = Rs * (255 - As);
+ Gss = Gs * (255 - As);
+ Bss = Bs * (255 - As);
+ Ass = As * (255 - As);
+ break;
+ case GL_DST_ALPHA:
+ Rss = Rs * Ad;
+ Gss = Gs * Ad;
+ Bss = Bs * Ad;
+ Ass = As * Ad;
+ break;
+ case GL_ONE_MINUS_DST_ALPHA:
+ Rss = Rs * (255 - Ad);
+ Gss = Gs * (255 - Ad);
+ Bss = Bs * (255 - Ad);
+ Ass = As * (255 - Ad);
+ break;
+ case GL_SRC_ALPHA_SATURATE:
+ {
+ GLint sA = MIN2(As, 255 - Ad);
+ Rss = Rs * sA;
+ Gss = Gs * sA;
+ Bss = Bs * sA;
+ Ass = As * 255;
+ break;
+ }
+ default:
+ /* this should never happen */
+ gl_problem(ctx, "Bad blend source factor in do_blend");
+ }
+
+ /* Dest scaling */
+ switch (ctx->Color.BlendDst) {
+ case GL_ZERO:
+ Rds = Gds = Bds = Ads = 0;
+ break;
+ case GL_ONE:
+ Rds = Rd * 255;
+ Gds = Gd * 255;
+ Bds = Bd * 255;
+ Ads = Ad * 255;
+ break;
+ case GL_SRC_COLOR:
+ Rds = Rd * Rs;
+ Gds = Gd * Gs;
+ Bds = Bd * Bs;
+ Ads = Ad * As;
+ break;
+ case GL_ONE_MINUS_SRC_COLOR:
+ Rds = Rs * (255 - Rs);
+ Gds = Gs * (255 - Gs);
+ Bds = Bs * (255 - Bs);
+ Ads = As * (255 - As);
+ break;
+ case GL_SRC_ALPHA:
+ Rds = Rd * As;
+ Gds = Gd * As;
+ Bds = Bd * As;
+ Ads = Ad * As;
+ break;
+ case GL_ONE_MINUS_SRC_ALPHA:
+ Rds = Rd * (255 - As);
+ Gds = Gd * (255 - As);
+ Bds = Bd * (255 - As);
+ Ads = Ad * (255 - As);
+ break;
+ case GL_DST_ALPHA:
+ Rds = Rd * Ad;
+ Gds = Gd * Ad;
+ Bds = Bd * Ad;
+ Ads = Ad * Ad;
+ break;
+ case GL_ONE_MINUS_DST_ALPHA:
+ Rds = Rd * (255 - Ad);
+ Gds = Gd * (255 - Ad);
+ Bds = Bd * (255 - Ad);
+ Ads = Ad * (255 - Ad);
+ break;
+ default:
+ /* this should never happen */
+ gl_problem(ctx, "Bad blend dest factor in do_blend");
+ }
+
+ /* compute blended color */
+ red[i] = MIN2((Rss + Rds) / 255, 255);
+ green[i] = MIN2((Gss + Gds) / 255, 255);
+ blue[i] = MIN2((Bss + Bds) / 255, 255);
+ alpha[i] = MIN2((Ass + Ads) / 255, 255);
+ }
+ }
+ }else{ /* !EightBitColor */
+ GLfloat rmax = ctx->Visual->RedScale;
+ GLfloat gmax = ctx->Visual->GreenScale;
+ GLfloat bmax = ctx->Visual->BlueScale;
+ GLfloat amax = ctx->Visual->AlphaScale;
+ GLfloat rscale = 1.0f / rmax;
+ GLfloat gscale = 1.0f / gmax;
+ GLfloat bscale = 1.0f / bmax;
+ GLfloat ascale = 1.0f / amax;
+
+ for (i=0;i<n;i++) {
+ if (mask[i]) {
+ GLint Rs, Gs, Bs, As; /* Source colors */
+ GLint Rd, Gd, Bd, Ad; /* Dest colors */
+ GLfloat sR, sG, sB, sA; /* Source scaling */
+ GLfloat dR, dG, dB, dA; /* Dest scaling */
+ GLfloat r, g, b, a;
+
+ /* Source Color */
+ Rs = red[i];
+ Gs = green[i];
+ Bs = blue[i];
+ As = alpha[i];
+
+ /* Frame buffer color */
+ Rd = rdest[i];
+ Gd = gdest[i];
+ Bd = bdest[i];
+ Ad = adest[i];
+
+ /* Source scaling */
+ switch (ctx->Color.BlendSrc) {
+ case GL_ZERO:
+ sR = sG = sB = sA = 0.0F;
+ break;
+ case GL_ONE:
+ sR = sG = sB = sA = 1.0F;
+ break;
+ case GL_DST_COLOR:
+ sR = (GLfloat) Rd * rscale;
+ sG = (GLfloat) Gd * gscale;
+ sB = (GLfloat) Bd * bscale;
+ sA = (GLfloat) Ad * ascale;
+ 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;
+ sA = 1.0F - (GLfloat) Ad * ascale;
+ break;
+ case GL_SRC_ALPHA:
+ sR = sG = sB = sA = (GLfloat) As * ascale;
+ break;
+ case GL_ONE_MINUS_SRC_ALPHA:
+ sR = sG = sB = sA = (GLfloat) 1.0F - (GLfloat) As * ascale;
+ break;
+ case GL_DST_ALPHA:
+ sR = sG = sB = sA =(GLfloat) Ad * ascale;
+ break;
+ case GL_ONE_MINUS_DST_ALPHA:
+ sR = sG = sB = sA = 1.0F - (GLfloat) Ad * ascale;
+ break;
+ case GL_SRC_ALPHA_SATURATE:
+ if (As < 1.0F - (GLfloat) Ad * ascale) {
+ sR = sG = sB = (GLfloat) As * ascale;
+ }
+ else {
+ sR = sG = sB = 1.0F - (GLfloat) Ad * ascale;
+ }
+ sA = 1.0;
+ break;
+ default:
+ /* this should never happen */
+ gl_problem(ctx, "Bad blend source factor in do_blend");
+ }
+
+ /* Dest scaling */
+ switch (ctx->Color.BlendDst) {
+ case GL_ZERO:
+ dR = dG = dB = dA = 0.0F;
+ break;
+ case GL_ONE:
+ dR = dG = dB = dA = 1.0F;
+ break;
+ case GL_SRC_COLOR:
+ dR = (GLfloat) Rs * rscale;
+ dG = (GLfloat) Gs * gscale;
+ dB = (GLfloat) Bs * bscale;
+ dA = (GLfloat) As * ascale;
+ break;
+ case GL_ONE_MINUS_SRC_COLOR:
+ dR = 1.0F - (GLfloat) Rs * rscale;
+ dG = 1.0F - (GLfloat) Gs * gscale;
+ dB = 1.0F - (GLfloat) Bs * bscale;
+ dA = 1.0F - (GLfloat) As * ascale;
+ break;
+ case GL_SRC_ALPHA:
+ dR = dG = dB = dA = (GLfloat) As * ascale;
+ break;
+ case GL_ONE_MINUS_SRC_ALPHA:
+ dR = dG = dB = dA = (GLfloat) 1.0F - (GLfloat) As * ascale;
+ break;
+ case GL_DST_ALPHA:
+ dR = dG = dB = dA = (GLfloat) Ad * ascale;
+ break;
+ case GL_ONE_MINUS_DST_ALPHA:
+ dR = dG = dB = dA = 1.0F - (GLfloat) Ad * ascale;
+ break;
+ default:
+ /* this should never happen */
+ gl_problem(ctx, "Bad blend dest factor in do_blend");
+ }
+
+#ifdef DEBUG
+ assert( sR>= 0.0 && sR<=1.0 );
+ assert( sG>= 0.0 && sG<=1.0 );
+ assert( sB>= 0.0 && sB<=1.0 );
+ assert( sA>= 0.0 && sA<=1.0 );
+ assert( dR>= 0.0 && dR<=1.0 );
+ assert( dG>= 0.0 && dG<=1.0 );
+ assert( dB>= 0.0 && dB<=1.0 );
+ assert( dA>= 0.0 && dA<=1.0 );
+#endif
+
+ /* compute blended color */
+ r = Rs * sR + Rd * dR;
+ g = Gs * sG + Gd * dG;
+ b = Bs * sB + Bd * dB;
+ a = As * sA + Ad * dA;
+ red[i] = (GLint) CLAMP( r, 0.0F, rmax );
+ green[i] = (GLint) CLAMP( g, 0.0F, gmax );
+ blue[i] = (GLint) CLAMP( b, 0.0F, bmax );
+ alpha[i] = (GLint) CLAMP( a, 0.0F, amax );
+ }
+ }
+ }
+ }
+ }
+
+}
+
+
+
+
+
+/*
+ * Apply the blending operator to a span of pixels.
+ * Input: n - number of pixels in span
+ * x, y - location of leftmost pixel in span in window coords.
+ * mask - boolean mask indicating which pixels to blend.
+ * In/Out: red, green, blue, alpha - pixel values
+ */
+void gl_blend_span( GLcontext* ctx, GLuint n, GLint x, GLint y,
+ GLubyte red[], GLubyte green[],
+ GLubyte blue[], GLubyte alpha[],
+ GLubyte mask[] )
+{
+ GLubyte rdest[MAX_WIDTH], gdest[MAX_WIDTH];
+ GLubyte bdest[MAX_WIDTH], adest[MAX_WIDTH];
+
+ /* Read span of current frame buffer pixels */
+ gl_read_color_span( ctx, n, x, y, rdest, gdest, bdest, adest );
+
+ do_blend( ctx, n, mask, red, green, blue, alpha, rdest, gdest, bdest, adest );
+}
+
+
+
+
+
+/*
+ * Apply the blending operator to an array of pixels.
+ * Input: n - number of pixels in span
+ * x, y - array of pixel locations
+ * mask - boolean mask indicating which pixels to blend.
+ * In/Out: red, green, blue, alpha - array of pixel values
+ */
+void gl_blend_pixels( GLcontext* ctx,
+ GLuint n, const GLint x[], const GLint y[],
+ GLubyte red[], GLubyte green[],
+ GLubyte blue[], GLubyte alpha[],
+ GLubyte mask[] )
+{
+ GLubyte rdest[PB_SIZE], gdest[PB_SIZE], bdest[PB_SIZE], adest[PB_SIZE];
+
+ /* Read pixels from current color buffer */
+ (*ctx->Driver.ReadColorPixels)( ctx, n, x, y, rdest, gdest, bdest, adest, mask );
+ if (ctx->RasterMask & ALPHABUF_BIT) {
+ gl_read_alpha_pixels( ctx, n, x, y, adest, mask );
+ }
+
+ do_blend( ctx, n, mask, red, green, blue, alpha, rdest, gdest, bdest, adest );
+}
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