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/* $Id: span.c,v 1.4 1996/09/25 03:22:05 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: span.c,v $
* Revision 1.4 1996/09/25 03:22:05 brianp
* added NO_DRAW_BIT support
*
* Revision 1.3 1996/09/15 14:18:55 brianp
* now use GLframebuffer and GLvisual
*
* Revision 1.2 1996/09/15 01:48:58 brianp
* removed #define NULL 0
*
* Revision 1.1 1996/09/13 01:38:16 brianp
* Initial revision
*
*/
/*
* pixel span rasterization:
* These functions simulate the rasterization pipeline.
*/
#include <string.h>
#include "alpha.h"
#include "alphabuf.h"
#include "blend.h"
#include "depth.h"
#include "fog.h"
#include "logic.h"
#include "macros.h"
#include "masking.h"
#include "scissor.h"
#include "span.h"
#include "stencil.h"
#include "texture.h"
#include "types.h"
/*
* Apply the current polygon stipple pattern to a span of pixels.
*/
static void stipple_polygon_span( GLcontext *ctx,
GLuint n, GLint x, GLint y, GLubyte mask[] )
{
register GLuint i, m, stipple, highbit=0x80000000;
stipple = ctx->PolygonStipple[y % 32];
m = highbit >> (GLuint) (x % 32);
for (i=0;i<n;i++) {
if ((m & stipple)==0) {
mask[i] = 0;
}
m = m >> 1;
if (m==0) {
m = 0x80000000;
}
}
}
/*
* Clip a pixel span to the current buffer/window boundaries.
* Return: 0 = all pixels clipped
* 1 = at least one pixel is visible
*/
static GLuint clip_span( GLcontext *ctx,
GLint n, GLint x, GLint y, GLubyte mask[] )
{
GLint i;
/* Clip to top and bottom */
if (y<0 || y>=ctx->Buffer->Height) {
return 0;
}
/* Clip to left and right */
if (x>=0 && x+n<=ctx->Buffer->Width) {
/* no clipping needed */
return 1;
}
else if (x+n<=0) {
/* completely off left side */
return 0;
}
else if (x>=ctx->Buffer->Width) {
/* completely off right side */
return 0;
}
else {
/* clip-test each pixel, this could be done better */
for (i=0;i<n;i++) {
if (x+i<0 || x+i>=ctx->Buffer->Width) {
mask[i] = 0;
}
}
return 1;
}
}
/*
* Write a horizontal span of color index pixels to the frame buffer.
* Stenciling, Depth-testing, etc. are done as needed.
* Input: n - number of pixels in the span
* x, y - location of leftmost pixel in the span
* z - array of [n] z-values
* index - array of [n] color indexes
* primitive - either GL_POINT, GL_LINE, GL_POLYGON, or GL_BITMAP
*/
void gl_write_index_span( GLcontext *ctx,
GLuint n, GLint x, GLint y, GLdepth z[],
GLuint index[], GLenum primitive )
{
GLuint i;
GLubyte mask[MAX_WIDTH];
GLuint index_save[MAX_WIDTH];
/* init mask to 1's (all pixels are to be written) */
for (i=0;i<n;i++)
mask[i] = 1;
if ((ctx->RasterMask & WINCLIP_BIT) || primitive==GL_BITMAP) {
if (clip_span(ctx,n,x,y,mask)==0) {
return;
}
}
/* Per-pixel fog */
if (ctx->Fog.Enabled
&& (ctx->Hint.Fog==GL_NICEST || primitive==GL_BITMAP)) {
gl_fog_index_pixels( ctx, n, z, index );
}
/* Do the scissor test */
if (ctx->Scissor.Enabled) {
if (gl_scissor_span( ctx, n, x, y, mask )==0) {
return;
}
}
/* Polygon Stippling */
if (ctx->Polygon.StippleFlag && primitive==GL_POLYGON) {
stipple_polygon_span( ctx, n, x, y, mask );
}
if (ctx->Stencil.Enabled) {
/* first stencil test */
if (gl_stencil_span( ctx, n, x, y, mask )==0) {
return;
}
/* depth buffering w/ stencil */
gl_depth_stencil_span( ctx, n, x, y, z, mask );
}
else if (ctx->Depth.Test) {
/* regular depth testing */
if ((*ctx->Driver.DepthTestSpan)( ctx, n, x, y, z, mask )==0) return;
}
if (ctx->RasterMask & NO_DRAW_BIT) {
/* write no pixels */
return;
}
if (ctx->RasterMask & FRONT_AND_BACK_BIT) {
/* Save a copy of the indexes since LogicOp and IndexMask
* may change them
*/
MEMCPY( index_save, index, n * sizeof(GLuint) );
}
if (ctx->Color.SWLogicOpEnabled) {
gl_logic_span( ctx, n, x, y, index, mask );
}
if (ctx->Color.SWmasking) {
gl_mask_index_span( ctx, n, x, y, index );
}
/* write pixels */
(*ctx->Driver.WriteIndexSpan)( ctx, n, x, y, index, mask );
if (ctx->RasterMask & FRONT_AND_BACK_BIT) {
/*** Also draw to back buffer ***/
(*ctx->Driver.SetBuffer)( ctx, GL_BACK );
MEMCPY( index, index_save, n * sizeof(GLuint) );
if (ctx->Color.SWLogicOpEnabled) {
gl_logic_span( ctx, n, x, y, index, mask );
}
if (ctx->Color.SWmasking) {
gl_mask_index_span( ctx, n, x, y, index );
}
(*ctx->Driver.WriteIndexSpan)( ctx, n, x, y, index, mask );
(*ctx->Driver.SetBuffer)( ctx, GL_FRONT );
}
}
void gl_write_monoindex_span( GLcontext *ctx,
GLuint n, GLint x, GLint y, GLdepth z[],
GLuint index, GLenum primitive )
{
GLuint i;
GLubyte mask[MAX_WIDTH];
GLuint index_save[MAX_WIDTH];
/* init mask to 1's (all pixels are to be written) */
for (i=0;i<n;i++)
mask[i] = 1;
if ((ctx->RasterMask & WINCLIP_BIT) || primitive==GL_BITMAP) {
if (clip_span( ctx,n,x,y,mask)==0) {
return;
}
}
/* Do the scissor test */
if (ctx->Scissor.Enabled) {
if (gl_scissor_span( ctx, n, x, y, mask )==0) {
return;
}
}
/* Polygon Stippling */
if (ctx->Polygon.StippleFlag && primitive==GL_POLYGON) {
stipple_polygon_span( ctx, n, x, y, mask );
}
if (ctx->Stencil.Enabled) {
/* first stencil test */
if (gl_stencil_span( ctx, n, x, y, mask )==0) {
return;
}
/* depth buffering w/ stencil */
gl_depth_stencil_span( ctx, n, x, y, z, mask );
}
else if (ctx->Depth.Test) {
/* regular depth testing */
if ((*ctx->Driver.DepthTestSpan)( ctx, n, x, y, z, mask )==0) return;
}
if (ctx->RasterMask & NO_DRAW_BIT) {
/* write no pixels */
return;
}
if ((ctx->Fog.Enabled && (ctx->Hint.Fog==GL_NICEST || primitive==GL_BITMAP))
|| ctx->Color.SWLogicOpEnabled || ctx->Color.SWmasking) {
GLuint ispan[MAX_WIDTH];
/* index may change, replicate single index into an array */
for (i=0;i<n;i++) {
ispan[i] = index;
}
if (ctx->Fog.Enabled
&& (ctx->Hint.Fog==GL_NICEST || primitive==GL_BITMAP)) {
gl_fog_index_pixels( ctx, n, z, ispan );
}
if (ctx->RasterMask & FRONT_AND_BACK_BIT) {
MEMCPY( index_save, index, n * sizeof(GLuint) );
}
if (ctx->Color.SWLogicOpEnabled) {
gl_logic_span( ctx, n, x, y, ispan, mask );
}
if (ctx->Color.SWmasking) {
gl_mask_index_span( ctx, n, x, y, ispan );
}
(*ctx->Driver.WriteIndexSpan)( ctx, n, x, y, ispan, mask );
if (ctx->RasterMask & FRONT_AND_BACK_BIT) {
/*** Also draw to back buffer ***/
(*ctx->Driver.SetBuffer)( ctx, GL_BACK );
for (i=0;i<n;i++) {
ispan[i] = index;
}
if (ctx->Color.SWLogicOpEnabled) {
gl_logic_span( ctx, n, x, y, ispan, mask );
}
if (ctx->Color.SWmasking) {
gl_mask_index_span( ctx, n, x, y, ispan );
}
(*ctx->Driver.WriteIndexSpan)( ctx, n, x, y, ispan, mask );
(*ctx->Driver.SetBuffer)( ctx, GL_FRONT );
}
}
else {
(*ctx->Driver.WriteMonoindexSpan)( ctx, n, x, y, mask );
if (ctx->RasterMask & FRONT_AND_BACK_BIT) {
/*** Also draw to back buffer ***/
(*ctx->Driver.SetBuffer)( ctx, GL_BACK );
(*ctx->Driver.WriteMonoindexSpan)( ctx, n, x, y, mask );
(*ctx->Driver.SetBuffer)( ctx, GL_FRONT );
}
}
}
void gl_write_color_span( GLcontext *ctx,
GLuint n, GLint x, GLint y, GLdepth z[],
GLubyte r[], GLubyte g[],
GLubyte b[], GLubyte a[],
GLenum primitive )
{
GLuint i;
GLubyte mask[MAX_WIDTH];
GLboolean write_all = GL_TRUE;
GLubyte rtmp[MAX_WIDTH], gtmp[MAX_WIDTH], btmp[MAX_WIDTH], atmp[MAX_WIDTH];
GLubyte *red, *green, *blue, *alpha;
/* init mask to 1's (all pixels are to be written) */
for (i=0;i<n;i++)
mask[i] = 1;
if ((ctx->RasterMask & WINCLIP_BIT) || primitive==GL_BITMAP) {
if (clip_span( ctx,n,x,y,mask)==0) {
return;
}
write_all = GL_FALSE;
}
if ((primitive==GL_BITMAP && ctx->MutablePixels)
|| (ctx->RasterMask & FRONT_AND_BACK_BIT)) {
/* must make a copy of the colors since they may be modified */
MEMCPY( rtmp, r, n * sizeof(GLubyte) );
MEMCPY( gtmp, g, n * sizeof(GLubyte) );
MEMCPY( btmp, b, n * sizeof(GLubyte) );
MEMCPY( atmp, a, n * sizeof(GLubyte) );
red = rtmp;
green = gtmp;
blue = btmp;
alpha = atmp;
}
else {
red = r;
green = g;
blue = b;
alpha = a;
}
/* Per-pixel fog */
if (ctx->Fog.Enabled
&& (ctx->Hint.Fog==GL_NICEST || primitive==GL_BITMAP)) {
gl_fog_color_pixels( ctx, n, z, red, green, blue, alpha );
}
/* Do the scissor test */
if (ctx->Scissor.Enabled) {
if (gl_scissor_span( ctx, n, x, y, mask )==0) {
return;
}
write_all = GL_FALSE;
}
/* Polygon Stippling */
if (ctx->Polygon.StippleFlag && primitive==GL_POLYGON) {
stipple_polygon_span( ctx, n, x, y, mask );
write_all = GL_FALSE;
}
/* Do the alpha test */
if (ctx->Color.AlphaEnabled) {
if (gl_alpha_test( ctx, n, alpha, mask )==0) {
return;
}
write_all = GL_FALSE;
}
if (ctx->Stencil.Enabled) {
/* first stencil test */
if (gl_stencil_span( ctx, n, x, y, mask )==0) {
return;
}
/* depth buffering w/ stencil */
gl_depth_stencil_span( ctx, n, x, y, z, mask );
write_all = GL_FALSE;
}
else if (ctx->Depth.Test) {
/* regular depth testing */
GLuint m = (*ctx->Driver.DepthTestSpan)( ctx, n, x, y, z, mask );
if (m==0) {
return;
}
if (m<n) {
write_all = GL_FALSE;
}
}
if (ctx->RasterMask & NO_DRAW_BIT) {
/* write no pixels */
return;
}
/* blending */
if (ctx->Color.BlendEnabled) {
gl_blend_span( ctx, n, x, y, red, green, blue, alpha, mask );
}
/* Color component masking */
if (ctx->Color.SWmasking) {
gl_mask_color_span( ctx, n, x, y, red, green, blue, alpha );
}
/* write pixels */
(*ctx->Driver.WriteColorSpan)( ctx, n, x, y, red, green, blue, alpha,
write_all ? NULL : mask );
if (ctx->RasterMask & ALPHABUF_BIT) {
gl_write_alpha_span( ctx, n, x, y, alpha, write_all ? NULL : mask );
}
if (ctx->RasterMask & FRONT_AND_BACK_BIT) {
/*** Also render to back buffer ***/
MEMCPY( rtmp, r, n * sizeof(GLubyte) );
MEMCPY( gtmp, g, n * sizeof(GLubyte) );
MEMCPY( btmp, b, n * sizeof(GLubyte) );
MEMCPY( atmp, a, n * sizeof(GLubyte) );
(*ctx->Driver.SetBuffer)( ctx, GL_BACK );
if (ctx->Color.BlendEnabled) {
gl_blend_span( ctx, n, x, y, red, green, blue, alpha, mask );
}
if (ctx->Color.SWmasking) {
gl_mask_color_span( ctx, n, x, y, red, green, blue, alpha );
}
(*ctx->Driver.WriteColorSpan)( ctx, n, x, y, red, green, blue, alpha,
write_all ? NULL : mask );
if (ctx->RasterMask & ALPHABUF_BIT) {
ctx->Buffer->Alpha = ctx->Buffer->BackAlpha;
gl_write_alpha_span( ctx, n, x, y, alpha, write_all ? NULL : mask );
ctx->Buffer->Alpha = ctx->Buffer->FrontAlpha;
}
(*ctx->Driver.SetBuffer)( ctx, GL_FRONT );
}
}
/*
* Write a horizontal span of color pixels to the frame buffer.
* The color is initially constant for the whole span.
* Alpha-testing, stenciling, depth-testing, and blending are done as needed.
* Input: n - number of pixels in the span
* x, y - location of leftmost pixel in the span
* z - array of [n] z-values
* r, g, b, a - the color of the pixels
* primitive - either GL_POINT, GL_LINE, GL_POLYGON or GL_BITMAP.
*/
void gl_write_monocolor_span( GLcontext *ctx,
GLuint n, GLint x, GLint y, GLdepth z[],
GLint r, GLint g, GLint b, GLint a,
GLenum primitive )
{
GLuint i;
GLubyte mask[MAX_WIDTH];
GLboolean write_all = GL_TRUE;
GLubyte red[MAX_WIDTH], green[MAX_WIDTH], blue[MAX_WIDTH], alpha[MAX_WIDTH];
/* init mask to 1's (all pixels are to be written) */
for (i=0;i<n;i++)
mask[i] = 1;
if ((ctx->RasterMask & WINCLIP_BIT) || primitive==GL_BITMAP) {
if (clip_span( ctx,n,x,y,mask)==0) {
return;
}
write_all = GL_FALSE;
}
/* Do the scissor test */
if (ctx->Scissor.Enabled) {
if (gl_scissor_span( ctx, n, x, y, mask )==0) {
return;
}
write_all = GL_FALSE;
}
/* Polygon Stippling */
if (ctx->Polygon.StippleFlag && primitive==GL_POLYGON) {
stipple_polygon_span( ctx, n, x, y, mask );
write_all = GL_FALSE;
}
/* Do the alpha test */
if (ctx->Color.AlphaEnabled) {
GLubyte alpha[MAX_WIDTH];
for (i=0;i<n;i++) {
alpha[i] = a;
}
if (gl_alpha_test( ctx, n, alpha, mask )==0) {
return;
}
write_all = GL_FALSE;
}
if (ctx->Stencil.Enabled) {
/* first stencil test */
if (gl_stencil_span( ctx, n, x, y, mask )==0) {
return;
}
/* depth buffering w/ stencil */
gl_depth_stencil_span( ctx, n, x, y, z, mask );
write_all = GL_FALSE;
}
else if (ctx->Depth.Test) {
/* regular depth testing */
GLuint m = (*ctx->Driver.DepthTestSpan)( ctx, n, x, y, z, mask );
if (m==0) {
return;
}
if (m<n) {
write_all = GL_FALSE;
}
}
if (ctx->RasterMask & NO_DRAW_BIT) {
/* write no pixels */
return;
}
if (ctx->Color.BlendEnabled || ctx->Color.SWmasking) {
/* assign same color to each pixel */
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = r;
green[i] = g;
blue[i] = b;
alpha[i] = a;
}
}
if (ctx->Color.BlendEnabled) {
gl_blend_span( ctx, n, x, y, red, green, blue, alpha, mask );
}
/* Color component masking */
if (ctx->Color.SWmasking) {
gl_mask_color_span( ctx, n, x, y, red, green, blue, alpha );
}
/* write pixels */
(*ctx->Driver.WriteColorSpan)( ctx, n, x, y, red, green, blue, alpha,
write_all ? NULL : mask );
if (ctx->RasterMask & ALPHABUF_BIT) {
gl_write_alpha_span( ctx, n, x, y, alpha, write_all ? NULL : mask );
}
if (ctx->RasterMask & FRONT_AND_BACK_BIT) {
/*** Also draw to back buffer ***/
for (i=0;i<n;i++) {
if (mask[i]) {
red[i] = r;
green[i] = g;
blue[i] = b;
alpha[i] = a;
}
}
(*ctx->Driver.SetBuffer)( ctx, GL_BACK );
if (ctx->Color.BlendEnabled) {
gl_blend_span( ctx, n, x, y, red, green, blue, alpha, mask );
}
if (ctx->Color.SWmasking) {
gl_mask_color_span( ctx, n, x, y, red, green, blue, alpha );
}
(*ctx->Driver.WriteColorSpan)( ctx, n, x, y, red, green, blue, alpha,
write_all ? NULL : mask );
(*ctx->Driver.SetBuffer)( ctx, GL_FRONT );
if (ctx->RasterMask & ALPHABUF_BIT) {
ctx->Buffer->Alpha = ctx->Buffer->BackAlpha;
gl_write_alpha_span( ctx, n, x, y, alpha,
write_all ? NULL : mask );
ctx->Buffer->Alpha = ctx->Buffer->FrontAlpha;
}
}
}
else {
(*ctx->Driver.WriteMonocolorSpan)( ctx, n, x, y, mask );
if (ctx->RasterMask & ALPHABUF_BIT) {
gl_write_mono_alpha_span( ctx, n, x, y, a, write_all ? NULL : mask );
}
if (ctx->RasterMask & FRONT_AND_BACK_BIT) {
/* Also draw to back buffer */
(*ctx->Driver.SetBuffer)( ctx, GL_BACK );
(*ctx->Driver.WriteMonocolorSpan)( ctx, n, x, y, mask );
(*ctx->Driver.SetBuffer)( ctx, GL_FRONT );
if (ctx->RasterMask & ALPHABUF_BIT) {
ctx->Buffer->Alpha = ctx->Buffer->BackAlpha;
gl_write_mono_alpha_span( ctx, n, x, y, a,
write_all ? NULL : mask );
ctx->Buffer->Alpha = ctx->Buffer->FrontAlpha;
}
}
}
}
/*
* Write a horizontal span of textured pixels to the frame buffer.
* The color of each pixel is different.
* Alpha-testing, stenciling, depth-testing, and blending are done
* as needed.
* Input: n - number of pixels in the span
* x, y - location of leftmost pixel in the span
* z - array of [n] z-values
* s, t - array of (s,t) texture coordinates for each pixel
* lambda - array of texture lambda values
* red, green, blue, alpha - array of [n] color components
* primitive - either GL_POINT, GL_LINE, GL_POLYGON or GL_BITMAP.
*/
void gl_write_texture_span( GLcontext *ctx,
GLuint n, GLint x, GLint y, GLdepth z[],
GLfloat s[], GLfloat t[], GLfloat lambda[],
GLubyte r[], GLubyte g[],
GLubyte b[], GLubyte a[],
GLenum primitive )
{
GLuint i;
GLubyte mask[MAX_WIDTH];
GLboolean write_all = GL_TRUE;
GLubyte rtmp[MAX_WIDTH], gtmp[MAX_WIDTH], btmp[MAX_WIDTH], atmp[MAX_WIDTH];
GLubyte *red, *green, *blue, *alpha;
/* init mask to 1's (all pixels are to be written) */
for (i=0;i<n;i++)
mask[i] = 1;
if ((ctx->RasterMask & WINCLIP_BIT) || primitive==GL_BITMAP) {
if (clip_span( ctx,n,x,y,mask)==0) {
return;
}
write_all = GL_FALSE;
}
if (primitive==GL_BITMAP || (ctx->RasterMask & FRONT_AND_BACK_BIT)) {
/* must make a copy of the colors since they may be modified */
MEMCPY( rtmp, r, n * sizeof(GLubyte) );
MEMCPY( gtmp, g, n * sizeof(GLubyte) );
MEMCPY( btmp, b, n * sizeof(GLubyte) );
MEMCPY( atmp, a, n * sizeof(GLubyte) );
red = rtmp;
green = gtmp;
blue = btmp;
alpha = atmp;
}
else {
red = r;
green = g;
blue = b;
alpha = a;
}
/* Texture */
if (ctx->Texture.Enabled & 2) {
gl_texture_pixels_2d( ctx, n, s, t, lambda, red, green, blue, alpha );
}
else if (ctx->Texture.Enabled & 1) {
gl_texture_pixels_1d( ctx, n, s, lambda, red, green, blue, alpha );
}
/* Per-pixel fog */
if (ctx->Fog.Enabled
&& (ctx->Hint.Fog==GL_NICEST || primitive==GL_BITMAP)) {
gl_fog_color_pixels( ctx, n, z, red, green, blue, alpha );
}
/* Do the scissor test */
if (ctx->Scissor.Enabled) {
if (gl_scissor_span( ctx, n, x, y, mask )==0) {
return;
}
write_all = GL_FALSE;
}
/* Polygon Stippling */
if (ctx->Polygon.StippleFlag && primitive==GL_POLYGON) {
stipple_polygon_span( ctx, n, x, y, mask );
write_all = GL_FALSE;
}
/* Do the alpha test */
if (ctx->Color.AlphaEnabled) {
if (gl_alpha_test( ctx, n, alpha, mask )==0) {
return;
}
write_all = GL_FALSE;
}
if (ctx->Stencil.Enabled) {
/* first stencil test */
if (gl_stencil_span( ctx, n, x, y, mask )==0) {
return;
}
/* depth buffering w/ stencil */
gl_depth_stencil_span( ctx, n, x, y, z, mask );
write_all = GL_FALSE;
}
else if (ctx->Depth.Test) {
/* regular depth testing */
GLuint m = (*ctx->Driver.DepthTestSpan)( ctx, n, x, y, z, mask );
if (m==0) {
return;
}
if (m<n) {
write_all = GL_FALSE;
}
}
if (ctx->RasterMask & NO_DRAW_BIT) {
/* write no pixels */
return;
}
/* blending */
if (ctx->Color.BlendEnabled) {
gl_blend_span( ctx, n, x, y, red, green, blue, alpha, mask );
}
if (ctx->Color.SWmasking) {
gl_mask_color_span( ctx, n, x, y, red, green, blue, alpha );
}
/* write pixels */
(*ctx->Driver.WriteColorSpan)( ctx, n, x, y, red, green, blue, alpha,
write_all ? NULL : mask );
if (ctx->RasterMask & ALPHABUF_BIT) {
gl_write_alpha_span( ctx, n, x, y, alpha, write_all ? NULL : mask );
}
if (ctx->RasterMask & FRONT_AND_BACK_BIT) {
/* Also draw to back buffer */
MEMCPY( rtmp, r, n * sizeof(GLubyte) );
MEMCPY( gtmp, g, n * sizeof(GLubyte) );
MEMCPY( btmp, b, n * sizeof(GLubyte) );
MEMCPY( atmp, a, n * sizeof(GLubyte) );
(*ctx->Driver.SetBuffer)( ctx, GL_BACK );
if (ctx->Color.BlendEnabled) {
gl_blend_span( ctx, n, x, y, red, green, blue, alpha, mask );
}
if (ctx->Color.SWmasking) {
gl_mask_color_span( ctx, n, x, y, red, green, blue, alpha );
}
(*ctx->Driver.WriteColorSpan)( ctx, n, x, y, red, green, blue, alpha,
write_all ? NULL : mask );
(*ctx->Driver.SetBuffer)( ctx, GL_FRONT );
if (ctx->RasterMask & ALPHABUF_BIT) {
ctx->Buffer->Alpha = ctx->Buffer->BackAlpha;
gl_write_alpha_span( ctx, n, x, y, alpha, write_all ? NULL : mask );
ctx->Buffer->Alpha = ctx->Buffer->FrontAlpha;
}
}
}
/*
* Read RGBA pixels from frame buffer. Clipping will be done to prevent
* reading ouside the buffer's boundaries.
*/
void gl_read_color_span( GLcontext *ctx,
GLuint n, GLint x, GLint y,
GLubyte red[], GLubyte green[],
GLubyte blue[], GLubyte alpha[] )
{
register GLuint i;
if (y<0 || y>=ctx->Buffer->Height || x>=ctx->Buffer->Width) {
/* completely above, below, or right */
for (i=0;i<n;i++) {
red[i] = green[i] = blue[i] = alpha[i] = 0;
}
}
else {
if (x>=0 && x+n<=ctx->Buffer->Width) {
/* OK */
(*ctx->Driver.ReadColorSpan)( ctx, n, x, y, red, green, blue, alpha );
if (ctx->RasterMask & ALPHABUF_BIT) {
gl_read_alpha_span( ctx, n, x, y, alpha );
}
}
else {
i = 0;
if (x<0) {
while (x<0 && n>0) {
red[i] = green[i] = blue[i] = alpha[i] = 0;
x++;
n--;
i++;
}
}
n = MIN2( n, ctx->Buffer->Width - x );
(*ctx->Driver.ReadColorSpan)( ctx, n, x, y, red+i, green+i, blue+i, alpha+i);
if (ctx->RasterMask & ALPHABUF_BIT) {
gl_read_alpha_span( ctx, n, x, y, alpha+i );
}
}
}
}
/*
* Read CI pixels from frame buffer. Clipping will be done to prevent
* reading ouside the buffer's boundaries.
*/
void gl_read_index_span( GLcontext *ctx,
GLuint n, GLint x, GLint y, GLuint indx[] )
{
register GLuint i;
if (y<0 || y>=ctx->Buffer->Height || x>=ctx->Buffer->Width) {
/* completely above, below, or right */
for (i=0;i<n;i++) {
indx[i] = 0;
}
}
else {
if (x>=0 && x+n<=ctx->Buffer->Width) {
/* OK */
(*ctx->Driver.ReadIndexSpan)( ctx, n, x, y, indx );
}
else {
i = 0;
if (x<0) {
while (x<0 && n>0) {
indx[i] = 0;
x++;
n--;
i++;
}
}
n = MIN2( n, ctx->Buffer->Width - x );
(*ctx->Driver.ReadIndexSpan)( ctx, n, x, y, indx+i );
}
}
}
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.