accum.c

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/* $Id: accum.c,v 1.5 1997/07/24 01:24:28 brianp Exp $ */
 
/*
 * Mesa 3-D graphics library
 * Version:  2.4
 * 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: accum.c,v $
 * Revision 1.5  1997/07/24 01:24:28  brianp
 * changed precompiled header symbol from PCH to PC_HEADER
 *
 * Revision 1.4  1997/05/28 03:23:09  brianp
 * added precompiled header (PCH) support
 *
 * Revision 1.3  1997/04/30 01:54:48  brianp
 * call gl_warning() if calling gl_Accum w/out accum buffer
 *
 * Revision 1.2  1996/09/15 14:19:44  brianp
 * now use GLframebuffer and GLvisual
 * added gl_alloc_accum_buffer()
 *
 * Revision 1.1  1996/09/13 01:38:16  brianp
 * Initial revision
 *
 */
 
 
#ifdef PC_HEADER
#include "all.h"
#else
#include <limits.h>
#include <stdlib.h>
#include <string.h>
#include "accum.h"
#include "context.h"
#include "dlist.h"
#include "macros.h"
#include "types.h"
#endif
 
 
void gl_alloc_accum_buffer( GLcontext *ctx )
{
   GLint n;
 
   if (ctx->Buffer->Accum) {
      free( ctx->Buffer->Accum );
      ctx->Buffer->Accum = NULL;
   }
 
   /* allocate accumulation buffer if not already present */
   n = ctx->Buffer->Width * ctx->Buffer->Height * 4 * sizeof(GLaccum);
   ctx->Buffer->Accum = (GLaccum *) malloc( n );
   if (!ctx->Buffer->Accum) {
      /* unable to setup accumulation buffer */
      gl_error( ctx, GL_OUT_OF_MEMORY, "glAccum" );
   }
}
 
 
 
void gl_ClearAccum( GLcontext *ctx,
                    GLfloat red, GLfloat green, GLfloat blue, GLfloat alpha )
{
   if (INSIDE_BEGIN_END(ctx)) {
      gl_error( ctx, GL_INVALID_OPERATION, "glAccum" );
      return;
   }
   ctx->Accum.ClearColor[0] = CLAMP( red, -1.0, 1.0 );
   ctx->Accum.ClearColor[1] = CLAMP( green, -1.0, 1.0 );
   ctx->Accum.ClearColor[2] = CLAMP( blue, -1.0, 1.0 );
   ctx->Accum.ClearColor[3] = CLAMP( alpha, -1.0, 1.0 );
}
 
 
 
 
void gl_Accum( GLcontext *ctx, GLenum op, GLfloat value )
{
   GLuint xpos, ypos, width, height;
   GLfloat acc_scale;
 
   if (INSIDE_BEGIN_END(ctx)) {
      gl_error( ctx, GL_INVALID_OPERATION, "glAccum" );
      return;
   }
 
   if (ctx->Visual->AccumBits==0 || !ctx->Buffer->Accum) {
      /* No accumulation buffer! */
      gl_warning(ctx, "Calling glAccum() without an accumulation buffer");
      return;
   }
 
   if (sizeof(GLaccum)==1) {
      acc_scale = 127.0;
   }
   else if (sizeof(GLaccum)==2) {
      acc_scale = 32767.0;
   }
   else {
      /* sizeof(GLaccum) > 2 (Cray) */
      acc_scale = (float) SHRT_MAX;
   }
 
   /* Determine region to operate upon. */
   if (ctx->Scissor.Enabled) {
      xpos = ctx->Scissor.X;
      ypos = ctx->Scissor.Y;
      width = ctx->Scissor.Width;
      height = ctx->Scissor.Height;
   }
   else {
      /* whole window */
      xpos = 0;
      ypos = 0;
      width = ctx->Buffer->Width;
      height = ctx->Buffer->Height;
   }
 
   switch (op) {
      case GL_ADD:
         {
        GLaccum ival, *acc;
        GLuint i, j;
 
        ival = (GLaccum) (value * acc_scale);
        for (j=0;j<height;j++) {
           acc = ctx->Buffer->Accum
                     + (ypos * ctx->Buffer->Width + xpos) * 4;
           for (i=0;i<width;i++) {
          *acc += ival;   acc++;   /* red */
          *acc += ival;   acc++;   /* green */
          *acc += ival;   acc++;   /* blue */
          *acc += ival;   acc++;   /* alpha */
           }
           ypos++;
        }
     }
     break;
      case GL_MULT:
     {
        GLaccum *acc;
        GLuint i, j;
 
        for (j=0;j<height;j++) {
           acc = ctx->Buffer->Accum
                     + (ypos * ctx->Buffer->Width + xpos) * 4;
           for (i=0;i<width;i++) {
          *acc = (GLaccum) ( (GLfloat) *acc * value );    acc++; /*r*/
          *acc = (GLaccum) ( (GLfloat) *acc * value );    acc++; /*g*/
          *acc = (GLaccum) ( (GLfloat) *acc * value );    acc++; /*g*/
          *acc = (GLaccum) ( (GLfloat) *acc * value );    acc++; /*a*/
           }
           ypos++;
        }
     }
     break;
      case GL_ACCUM:
     {
        GLaccum *acc;
        GLubyte red[MAX_WIDTH], green[MAX_WIDTH];
        GLubyte blue[MAX_WIDTH], alpha[MAX_WIDTH];
        GLfloat rscale, gscale, bscale, ascale;
        GLuint i, j;
 
        (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.ReadBuffer );
 
        /* Accumulate */
        rscale = value * acc_scale * ctx->Visual->InvRedScale;
        gscale = value * acc_scale * ctx->Visual->InvGreenScale;
        bscale = value * acc_scale * ctx->Visual->InvBlueScale;
        ascale = value * acc_scale * ctx->Visual->InvAlphaScale;
        for (j=0;j<height;j++) {
           (*ctx->Driver.ReadColorSpan)( ctx, width, xpos, ypos,
                                             red, green, blue, alpha);
           acc = ctx->Buffer->Accum
                     + (ypos * ctx->Buffer->Width + xpos) * 4;
           for (i=0;i<width;i++) {
          *acc += (GLaccum) ( (GLfloat) red[i]   * rscale );  acc++;
          *acc += (GLaccum) ( (GLfloat) green[i] * gscale );  acc++;
          *acc += (GLaccum) ( (GLfloat) blue[i]  * bscale );  acc++;
          *acc += (GLaccum) ( (GLfloat) alpha[i] * ascale );  acc++;
           }
           ypos++;
        }
 
        (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DrawBuffer );
     }
     break;
      case GL_LOAD:
     {
        GLaccum *acc;
        GLubyte red[MAX_WIDTH], green[MAX_WIDTH];
        GLubyte blue[MAX_WIDTH], alpha[MAX_WIDTH];
        GLfloat rscale, gscale, bscale, ascale;
        GLuint i, j;
 
        (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Pixel.ReadBuffer );
 
        /* Load accumulation buffer */
        rscale = value * acc_scale * ctx->Visual->InvRedScale;
        gscale = value * acc_scale * ctx->Visual->InvGreenScale;
        bscale = value * acc_scale * ctx->Visual->InvBlueScale;
        ascale = value * acc_scale * ctx->Visual->InvAlphaScale;
        for (j=0;j<height;j++) {
           (*ctx->Driver.ReadColorSpan)( ctx, width, xpos, ypos,
                                             red, green, blue, alpha);
           acc = ctx->Buffer->Accum
                     + (ypos * ctx->Buffer->Width + xpos) * 4;
           for (i=0;i<width;i++) {
          *acc++ = (GLaccum) ( (GLfloat) red[i]   * rscale );
          *acc++ = (GLaccum) ( (GLfloat) green[i] * gscale );
          *acc++ = (GLaccum) ( (GLfloat) blue[i]  * bscale );
          *acc++ = (GLaccum) ( (GLfloat) alpha[i] * ascale );
           }
           ypos++;
        }
 
        (void) (*ctx->Driver.SetBuffer)( ctx, ctx->Color.DrawBuffer );
     }
     break;
      case GL_RETURN:
     {
        GLubyte red[MAX_WIDTH], green[MAX_WIDTH];
        GLubyte blue[MAX_WIDTH], alpha[MAX_WIDTH];
        GLaccum *acc;
        GLfloat rscale, gscale, bscale, ascale;
        GLint rmax, gmax, bmax, amax;
        GLuint i, j;
 
        rscale = value / acc_scale * ctx->Visual->RedScale;
        gscale = value / acc_scale * ctx->Visual->GreenScale;
        bscale = value / acc_scale * ctx->Visual->BlueScale;
        ascale = value / acc_scale * ctx->Visual->AlphaScale;
        rmax = (GLint) ctx->Visual->RedScale;
        gmax = (GLint) ctx->Visual->GreenScale;
        bmax = (GLint) ctx->Visual->BlueScale;
        amax = (GLint) ctx->Visual->AlphaScale;
        for (j=0;j<height;j++) {
           acc = ctx->Buffer->Accum
                     + (ypos * ctx->Buffer->Width + xpos) * 4;
           for (i=0;i<width;i++) {
          GLint r, g, b, a;
          r = (GLint) ( (GLfloat) (*acc++) * rscale + 0.5F );
          g = (GLint) ( (GLfloat) (*acc++) * gscale + 0.5F );
          b = (GLint) ( (GLfloat) (*acc++) * bscale + 0.5F );
          a = (GLint) ( (GLfloat) (*acc++) * ascale + 0.5F );
          red[i]   = CLAMP( r, 0, rmax );
          green[i] = CLAMP( g, 0, gmax );
          blue[i]  = CLAMP( b, 0, bmax );
          alpha[i] = CLAMP( a, 0, amax );
           }
           (*ctx->Driver.WriteColorSpan)( ctx, width, xpos, ypos,
                                              red, green, blue, alpha, NULL );
           ypos++;
        }
     }
     break;
      default:
         gl_error( ctx, GL_INVALID_ENUM, "glAccum" );
   }
}
 
 
 
 
/*
 * Clear the accumulation Buffer->
 */
void gl_clear_accum_buffer( GLcontext *ctx )
{
   GLuint buffersize;
   GLfloat acc_scale;
 
   if (ctx->Visual->AccumBits==0) {
      /* No accumulation buffer! */
      return;
   }
 
   if (sizeof(GLaccum)==1) {
      acc_scale = 127.0;
   }
   else if (sizeof(GLaccum)==2) {
      acc_scale = 32767.0;
   }
   else {
      /* sizeof(GLaccum) > 2 (Cray) */
      acc_scale = (float) SHRT_MAX;
   }
 
   /* number of pixels */
   buffersize = ctx->Buffer->Width * ctx->Buffer->Height;
 
   if (!ctx->Buffer->Accum) {
      /* try to alloc accumulation buffer */
      ctx->Buffer->Accum = (GLaccum *)
                       malloc( buffersize * 4 * sizeof(GLaccum) );
   }
 
   if (ctx->Buffer->Accum) {
      if (ctx->Scissor.Enabled) {
     /* Limit clear to scissor box */
     GLaccum r, g, b, a;
     GLint i, j;
         GLint width, height;
         GLaccum *row;
     r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
     g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
     b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
     a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
         /* size of region to clear */
         width = 4 * (ctx->Buffer->Xmax - ctx->Buffer->Xmin + 1);
         height = ctx->Buffer->Ymax - ctx->Buffer->Ymin + 1;
         /* ptr to first element to clear */
         row = ctx->Buffer->Accum
               + 4 * (ctx->Buffer->Ymin * ctx->Buffer->Width
                      + ctx->Buffer->Xmin);
         for (j=0;j<height;j++) {
            for (i=0;i<width;i+=4) {
               row[i+0] = r;
               row[i+1] = g;
               row[i+2] = b;
               row[i+3] = a;
        }
            row += 4 * ctx->Buffer->Width;
     }
      }
      else {
     /* clear whole buffer */
     if (ctx->Accum.ClearColor[0]==0.0 &&
         ctx->Accum.ClearColor[1]==0.0 &&
         ctx->Accum.ClearColor[2]==0.0 &&
         ctx->Accum.ClearColor[3]==0.0) {
        /* Black */
        MEMSET( ctx->Buffer->Accum, 0, buffersize * 4 * sizeof(GLaccum) );
     }
     else {
        /* Not black */
        GLaccum *acc, r, g, b, a;
        GLuint i;
 
        acc = ctx->Buffer->Accum;
        r = (GLaccum) (ctx->Accum.ClearColor[0] * acc_scale);
        g = (GLaccum) (ctx->Accum.ClearColor[1] * acc_scale);
        b = (GLaccum) (ctx->Accum.ClearColor[2] * acc_scale);
        a = (GLaccum) (ctx->Accum.ClearColor[3] * acc_scale);
        for (i=0;i<buffersize;i++) {
           *acc++ = r;
           *acc++ = g;
           *acc++ = b;
           *acc++ = a;
        }
     }
      }
   }
}