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/* $Id: blend.c,v 1.3 1996/09/19 00:53:31 brianp Exp $ */
/*
* Mesa 3-D graphics library
* Version: 2.0
* Copyright (C) 1995-1996 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 1.3 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 DEBUG
# include <assert.h>
#endif
#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"
void gl_BlendFunc( GLcontext* ctx, GLenum sfactor, GLenum dfactor )
{
if (INSIDE_BEGIN_END(ctx)) {
gl_error( ctx, GL_INVALID_OPERATION, "glBlendFunction" );
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:
case GL_CONSTANT_COLOR:
case GL_ONE_MINUS_CONSTANT_COLOR:
case GL_CONSTANT_ALPHA:
case GL_ONE_MINUS_CONSTANT_ALPHA:
ctx->Color.BlendSrc = sfactor;
break;
default:
gl_error( ctx, GL_INVALID_ENUM, "glBlendFunction" );
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:
case GL_CONSTANT_COLOR:
case GL_ONE_MINUS_CONSTANT_COLOR:
case GL_CONSTANT_ALPHA:
case GL_ONE_MINUS_CONSTANT_ALPHA:
ctx->Color.BlendDst = dfactor;
break;
default:
gl_error( ctx, GL_INVALID_ENUM, "glBlendFunction" );
}
ctx->NewState |= NEW_RASTER_OPS;
}
/* This is really an extension function! */
void gl_BlendEquation( GLcontext* ctx, GLenum mode )
{
if (INSIDE_BEGIN_END(ctx)) {
gl_error( ctx, GL_INVALID_OPERATION, "glBlendEquation" );
return;
}
switch (mode) {
case GL_MIN_EXT:
case GL_MAX_EXT:
case GL_LOGIC_OP:
case GL_FUNC_ADD_EXT:
case GL_FUNC_SUBTRACT_EXT:
case GL_FUNC_REVERSE_SUBTRACT_EXT:
ctx->Color.BlendEquation = mode;
break;
default:
gl_error( ctx, GL_INVALID_ENUM, "glBlendEquation" );
return;
}
ctx->NewState |= NEW_RASTER_OPS;
}
void gl_BlendColor( GLcontext* ctx, GLclampf red, GLclampf green,
GLclampf blue, GLclampf alpha )
{
ctx->Color.BlendColor[0] = CLAMP( red, 0.0, 1.0 );
ctx->Color.BlendColor[1] = CLAMP( green, 0.0, 1.0 );
ctx->Color.BlendColor[2] = CLAMP( blue, 0.0, 1.0 );
ctx->Color.BlendColor[3] = CLAMP( alpha, 0.0, 1.0 );
}
/*
* 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;
/* Common cases: */
if (ctx->Color.BlendEquation==GL_FUNC_ADD_EXT
&& 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;
red[i] = MIN2( r, rmax );
green[i] = MIN2( g, gmax );
blue[i] = MIN2( b, bmax );
alpha[i] = MIN2( a, amax );
}
}
}
else if (ctx->Color.BlendEquation==GL_LOGIC_OP
&& ctx->Color.LogicOp==GL_XOR) {
/* XOR drawing */
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] ^= rdest[i];
green[i] ^= gdest[i];
blue[i] ^= bdest[i];
alpha[i] ^= adest[i];
}
}
}
/* General cases: */
else if (ctx->Color.BlendEquation==GL_FUNC_ADD_EXT
|| ctx->Color.BlendEquation==GL_FUNC_SUBTRACT_EXT
|| ctx->Color.BlendEquation==GL_FUNC_REVERSE_SUBTRACT_EXT) {
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;
case GL_CONSTANT_COLOR:
sR = ctx->Color.BlendColor[0];
sG = ctx->Color.BlendColor[1];
sB = ctx->Color.BlendColor[2];
sA = ctx->Color.BlendColor[3];
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];
sA = 1.0F - ctx->Color.BlendColor[3];
break;
case GL_CONSTANT_ALPHA:
sR = sG = sB = sA = ctx->Color.BlendColor[3];
break;
case GL_ONE_MINUS_CONSTANT_ALPHA:
sR = sG = sB = sA = 1.0F - ctx->Color.BlendColor[3];
break;
default:
/* this should never happen */
abort();
}
/* 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;
case GL_CONSTANT_COLOR:
dR = ctx->Color.BlendColor[0];
dG = ctx->Color.BlendColor[1];
dB = ctx->Color.BlendColor[2];
dA = ctx->Color.BlendColor[3];
break;
case GL_ONE_MINUS_CONSTANT_COLOR:
dR = 1.0F - ctx->Color.BlendColor[0];
dG = 1.0F - ctx->Color.BlendColor[1];
dB = 1.0F - ctx->Color.BlendColor[2];
dA = 1.0F - ctx->Color.BlendColor[3];
break;
case GL_CONSTANT_ALPHA:
dR = dG = dB = dA = ctx->Color.BlendColor[3];
break;
case GL_ONE_MINUS_CONSTANT_ALPHA:
dR = dG = dB = dA = 1.0F - ctx->Color.BlendColor[3] * ascale;
break;
default:
/* this should never happen */
abort();
}
#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 */
if (ctx->Color.BlendEquation==GL_FUNC_ADD_EXT) {
r = Rs * sR + Rd * dR;
g = Gs * sG + Gd * dG;
b = Bs * sB + Bd * dB;
a = As * sA + Ad * dA;
}
else if (ctx->Color.BlendEquation==GL_FUNC_SUBTRACT_EXT) {
r = Rs * sR - Rd * dR;
g = Gs * sG - Gd * dG;
b = Bs * sB - Bd * dB;
a = As * sA - Ad * dA;
}
else if (ctx->Color.BlendEquation==GL_FUNC_REVERSE_SUBTRACT_EXT) {
r = Rd * dR - Rs * sR;
g = Gd * dG - Gs * sG;
b = Bd * dB - Bs * sB;
a = Ad * dA - As * sA;
}
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 );
}
}
}
else if (ctx->Color.BlendEquation==GL_LOGIC_OP) {
/* EXTENSION */
switch (ctx->Color.LogicOp) {
case GL_CLEAR:
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = green[i] = blue[i] = alpha[i] = 0;
}
}
break;
case GL_SET:
{
GLubyte r = (GLint) ctx->Visual->RedScale;
GLubyte g = (GLint) ctx->Visual->GreenScale;
GLubyte b = (GLint) ctx->Visual->BlueScale;
GLubyte a = (GLint) ctx->Visual->AlphaScale;
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = r;
green[i] = g;
blue[i] = b;
alpha[i] = a;
}
}
}
break;
case GL_COPY:
/* do nothing */
break;
case GL_COPY_INVERTED:
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = !red[i];
green[i] = !green[i];
blue[i] = !blue[i];
alpha[i] = !alpha[i];
}
}
break;
case GL_NOOP:
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = rdest[i];
green[i] = gdest[i];
blue[i] = bdest[i];
alpha[i] = adest[i];
}
}
break;
case GL_INVERT:
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = !rdest[i];
green[i] = !gdest[i];
blue[i] = !bdest[i];
alpha[i] = !adest[i];
}
}
break;
case GL_AND:
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] &= rdest[i];
green[i] &= gdest[i];
blue[i] &= bdest[i];
alpha[i] &= adest[i];
}
}
break;
case GL_NAND:
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = !(red[i] & rdest[i]);
green[i] = !(green[i] & gdest[i]);
blue[i] = !(blue[i] & bdest[i]);
alpha[i] = !(alpha[i] & adest[i]);
}
}
break;
case GL_OR:
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] |= rdest[i];
green[i] |= gdest[i];
blue[i] |= bdest[i];
alpha[i] |= adest[i];
}
}
break;
case GL_NOR:
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = !(red[i] | rdest[i]);
green[i] = !(green[i] | gdest[i]);
blue[i] = !(blue[i] | bdest[i]);
alpha[i] = !(alpha[i] | adest[i]);
}
}
break;
case GL_XOR:
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] ^= rdest[i];
green[i] ^= gdest[i];
blue[i] ^= bdest[i];
alpha[i] ^= adest[i];
}
}
break;
case GL_EQUIV:
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = !(red[i] ^ rdest[i]);
green[i] = !(green[i] ^ gdest[i]);
blue[i] = !(blue[i] ^ bdest[i]);
alpha[i] = !(alpha[i] ^ adest[i]);
}
}
break;
case GL_AND_REVERSE:
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = red[i] & !rdest[i];
green[i] = green[i] & !gdest[i];
blue[i] = blue[i] & !bdest[i];
alpha[i] = alpha[i] & !adest[i];
}
}
break;
case GL_AND_INVERTED:
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = !red[i] & rdest[i];
green[i] = !green[i] & gdest[i];
blue[i] = !blue[i] & bdest[i];
alpha[i] = !alpha[i] & adest[i];
}
}
break;
case GL_OR_REVERSE:
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = red[i] | !rdest[i];
green[i] = green[i] | !gdest[i];
blue[i] = blue[i] | !bdest[i];
alpha[i] = alpha[i] | !adest[i];
}
}
break;
case GL_OR_INVERTED:
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = !red[i] | rdest[i];
green[i] = !green[i] | gdest[i];
blue[i] = !blue[i] | bdest[i];
alpha[i] = !alpha[i] | adest[i];
}
}
break;
default:
; /* nothing */
}
}
else if (ctx->Color.BlendEquation==GL_MIN_EXT) {
/* EXTENSION */
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = MIN2( red[i], rdest[i] );
green[i] = MIN2( green[i], gdest[i] );
blue[i] = MIN2( blue[i], bdest[i] );
alpha[i] = MIN2( alpha[i], adest[i] );
}
}
}
else if (ctx->Color.BlendEquation==GL_MAX_EXT) {
/* EXTENSION */
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = MAX2( red[i], rdest[i] );
green[i] = MAX2( green[i], gdest[i] );
blue[i] = MAX2( blue[i], bdest[i] );
alpha[i] = MAX2( alpha[i], adest[i] );
}
}
}
}
/*
* 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];
/* Check if device driver can do the work */
if (ctx->Color.BlendEquation==GL_LOGIC_OP && !ctx->Color.SWLogicOpEnabled) {
return;
}
/* 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];
/* Check if device driver can do the work */
if (ctx->Color.BlendEquation==GL_LOGIC_OP && !ctx->Color.SWLogicOpEnabled) {
return;
}
/* 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 );
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.