s_accum.c

Mesa is an open-source implementation of the OpenGL specification - a system for rendering interacti

         GLshort *acc;
         if (directAccess) {
            acc = (GLshort *) rb->GetPointer(ctx, rb, xpos, ypos + i);
         }
         else {
            rb->GetRow(ctx, rb, width, xpos, ypos + i, accumRow);
            acc = accumRow;
         }

         /* read colors from color buffer */
         _swrast_read_rgba_span(ctx, ctx->ReadBuffer->_ColorReadBuffer, width,
                                xpos, ypos + i, CHAN_TYPE, rgba);

         /* do accumulation */
         if (swrast->_IntegerAccumMode) {
            /* simply add integer color values into accum buffer */
            GLint j;
            for (j = 0; j < width; j++) {
               acc[j * 4 + 0] += rgba[j][RCOMP];
               acc[j * 4 + 1] += rgba[j][GCOMP];
               acc[j * 4 + 2] += rgba[j][BCOMP];
               acc[j * 4 + 3] += rgba[j][ACOMP];
            }
         }
         else {
            /* scaled integer (or float) accum buffer */
            GLint j;
            for (j = 0; j < width; j++) {
               acc[j * 4 + 0] += (GLshort) ((GLfloat) rgba[j][RCOMP] * scale);
               acc[j * 4 + 1] += (GLshort) ((GLfloat) rgba[j][GCOMP] * scale);
               acc[j * 4 + 2] += (GLshort) ((GLfloat) rgba[j][BCOMP] * scale);
               acc[j * 4 + 3] += (GLshort) ((GLfloat) rgba[j][ACOMP] * scale);
            }
         }

         if (!directAccess) {
            rb->PutRow(ctx, rb, width, xpos, ypos + i, accumRow, NULL);
         }
      }
   }
   else {
      /* other types someday */
   }
}



static void
accum_load(GLcontext *ctx, GLfloat value,
           GLint xpos, GLint ypos, GLint width, GLint height )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   struct gl_renderbuffer *rb
      = ctx->DrawBuffer->Attachment[BUFFER_ACCUM].Renderbuffer;
   const GLboolean directAccess = (rb->GetPointer(ctx, rb, 0, 0) != NULL);

   assert(rb);

   if (!ctx->ReadBuffer->_ColorReadBuffer) {
      /* no read buffer - OK */
      return;
   }

   /* This is a change to go into optimized accum buffer mode */
   if (value > 0.0 && value <= 1.0) {
#if USE_OPTIMIZED_ACCUM
      swrast->_IntegerAccumMode = GL_TRUE;
#else
      swrast->_IntegerAccumMode = GL_FALSE;
#endif
      swrast->_IntegerAccumScaler = value;
   }
   else {
      swrast->_IntegerAccumMode = GL_FALSE;
      swrast->_IntegerAccumScaler = 0.0;
   }

   if (rb->DataType == GL_SHORT || rb->DataType == GL_UNSIGNED_SHORT) {
      const GLfloat scale = value * ACCUM_SCALE16 / CHAN_MAXF;
      GLshort accumRow[4 * MAX_WIDTH];
      GLchan rgba[MAX_WIDTH][4];
      GLint i;

      for (i = 0; i < height; i++) {
         GLshort *acc;
         if (directAccess) {
            acc = (GLshort *) rb->GetPointer(ctx, rb, xpos, ypos + i);
         }
         else {
            rb->GetRow(ctx, rb, width, xpos, ypos + i, accumRow);
            acc = accumRow;
         }

         /* read colors from color buffer */
         _swrast_read_rgba_span(ctx, ctx->ReadBuffer->_ColorReadBuffer, width,
                                xpos, ypos + i, CHAN_TYPE, rgba);

         /* do load */
         if (swrast->_IntegerAccumMode) {
            /* just copy values in */
            GLint j;
            assert(swrast->_IntegerAccumScaler > 0.0);
            assert(swrast->_IntegerAccumScaler <= 1.0);
            for (j = 0; j < width; j++) {
               acc[j * 4 + 0] = rgba[j][RCOMP];
               acc[j * 4 + 1] = rgba[j][GCOMP];
               acc[j * 4 + 2] = rgba[j][BCOMP];
               acc[j * 4 + 3] = rgba[j][ACOMP];
            }
         }
         else {
            /* scaled integer (or float) accum buffer */
            GLint j;
            for (j = 0; j < width; j++) {
               acc[j * 4 + 0] = (GLshort) ((GLfloat) rgba[j][RCOMP] * scale);
               acc[j * 4 + 1] = (GLshort) ((GLfloat) rgba[j][GCOMP] * scale);
               acc[j * 4 + 2] = (GLshort) ((GLfloat) rgba[j][BCOMP] * scale);
               acc[j * 4 + 3] = (GLshort) ((GLfloat) rgba[j][ACOMP] * scale);
            }
         }

         if (!directAccess) {
            rb->PutRow(ctx, rb, width, xpos, ypos + i, accumRow, NULL);
         }
      }
   }
}


static void
accum_return(GLcontext *ctx, GLfloat value,
             GLint xpos, GLint ypos, GLint width, GLint height )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   struct gl_framebuffer *fb = ctx->DrawBuffer;
   struct gl_renderbuffer *accumRb = fb->Attachment[BUFFER_ACCUM].Renderbuffer;
   const GLboolean directAccess
      = (accumRb->GetPointer(ctx, accumRb, 0, 0) != NULL);
   const GLboolean masking = (!ctx->Color.ColorMask[RCOMP] ||
                              !ctx->Color.ColorMask[GCOMP] ||
                              !ctx->Color.ColorMask[BCOMP] ||
                              !ctx->Color.ColorMask[ACOMP]);

   static GLchan multTable[32768];
   static GLfloat prevMult = 0.0;
   const GLfloat mult = swrast->_IntegerAccumScaler;
   const GLint max = MIN2((GLint) (256 / mult), 32767);

   /* May have to leave optimized accum buffer mode */
   if (swrast->_IntegerAccumMode && value != 1.0)
      rescale_accum(ctx);

   if (swrast->_IntegerAccumMode && swrast->_IntegerAccumScaler > 0) {
      /* build lookup table to avoid many floating point multiplies */
      GLint j;
      assert(swrast->_IntegerAccumScaler <= 1.0);
      if (mult != prevMult) {
         for (j = 0; j < max; j++)
            multTable[j] = IROUND((GLfloat) j * mult);
         prevMult = mult;
      }
   }

   if (accumRb->DataType == GL_SHORT ||
       accumRb->DataType == GL_UNSIGNED_SHORT) {
      const GLfloat scale = value * CHAN_MAXF / ACCUM_SCALE16;
      GLuint buffer;
      GLint i;

      /* XXX maybe transpose the 'i' and 'buffer' loops??? */
      for (i = 0; i < height; i++) {
         GLshort accumRow[4 * MAX_WIDTH];
         GLshort *acc;
         SWspan span;

         /* init color span */
         INIT_SPAN(span, GL_BITMAP);
         span.end = width;
         span.arrayMask = SPAN_RGBA;
         span.x = xpos;
         span.y = ypos + i;

         if (directAccess) {
            acc = (GLshort *) accumRb->GetPointer(ctx, accumRb, xpos, ypos +i);
         }
         else {
            accumRb->GetRow(ctx, accumRb, width, xpos, ypos + i, accumRow);
            acc = accumRow;
         }

         /* get the colors to return */
         if (swrast->_IntegerAccumMode) {
            GLint j;
            for (j = 0; j < width; j++) {
               ASSERT(acc[j * 4 + 0] < max);
               ASSERT(acc[j * 4 + 1] < max);
               ASSERT(acc[j * 4 + 2] < max);
               ASSERT(acc[j * 4 + 3] < max);
               span.array->rgba[j][RCOMP] = multTable[acc[j * 4 + 0]];
               span.array->rgba[j][GCOMP] = multTable[acc[j * 4 + 1]];
               span.array->rgba[j][BCOMP] = multTable[acc[j * 4 + 2]];
               span.array->rgba[j][ACOMP] = multTable[acc[j * 4 + 3]];
            }
         }
         else {
            /* scaled integer (or float) accum buffer */
            GLint j;
            for (j = 0; j < width; j++) {
#if CHAN_BITS==32
               GLchan r = acc[j * 4 + 0] * scale;
               GLchan g = acc[j * 4 + 1] * scale;
               GLchan b = acc[j * 4 + 2] * scale;
               GLchan a = acc[j * 4 + 3] * scale;
#else
               GLint r = IROUND( (GLfloat) (acc[j * 4 + 0]) * scale );
               GLint g = IROUND( (GLfloat) (acc[j * 4 + 1]) * scale );
               GLint b = IROUND( (GLfloat) (acc[j * 4 + 2]) * scale );
               GLint a = IROUND( (GLfloat) (acc[j * 4 + 3]) * scale );
#endif
               span.array->rgba[j][RCOMP] = CLAMP( r, 0, CHAN_MAX );
               span.array->rgba[j][GCOMP] = CLAMP( g, 0, CHAN_MAX );
               span.array->rgba[j][BCOMP] = CLAMP( b, 0, CHAN_MAX );
               span.array->rgba[j][ACOMP] = CLAMP( a, 0, CHAN_MAX );
            }
         }

         /* store colors */
         for (buffer = 0; buffer < fb->_NumColorDrawBuffers; buffer++) {
            struct gl_renderbuffer *rb = fb->_ColorDrawBuffers[buffer];
            if (masking) {
               _swrast_mask_rgba_span(ctx, rb, &span);
            }
            rb->PutRow(ctx, rb, width, xpos, ypos + i, span.array->rgba, NULL);
         }
      }
   }
   else {
      /* other types someday */
   }
}



/**
 * Software fallback for glAccum.
 */
void
_swrast_Accum(GLcontext *ctx, GLenum op, GLfloat value)
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   GLint xpos, ypos, width, height;

   if (SWRAST_CONTEXT(ctx)->NewState)
      _swrast_validate_derived( ctx );

   if (!ctx->DrawBuffer->Attachment[BUFFER_ACCUM].Renderbuffer) {
      _mesa_warning(ctx, "Calling glAccum() without an accumulation buffer");
      return;
   }

   RENDER_START(swrast, ctx);

   /* Compute region after calling RENDER_START so that we know the
    * drawbuffer's size/bounds are up to date.
    */
   xpos = ctx->DrawBuffer->_Xmin;
   ypos = ctx->DrawBuffer->_Ymin;
   width =  ctx->DrawBuffer->_Xmax - ctx->DrawBuffer->_Xmin;
   height = ctx->DrawBuffer->_Ymax - ctx->DrawBuffer->_Ymin;

   switch (op) {
      case GL_ADD:
         if (value != 0.0F) {
            accum_add(ctx, value, xpos, ypos, width, height);
	 }
	 break;
      case GL_MULT:
         if (value != 1.0F) {
            accum_mult(ctx, value, xpos, ypos, width, height);
	 }
	 break;
      case GL_ACCUM:
         if (value != 0.0F) {
            accum_accum(ctx, value, xpos, ypos, width, height);
         }
	 break;
      case GL_LOAD:
         accum_load(ctx, value, xpos, ypos, width, height);
	 break;
      case GL_RETURN:
         accum_return(ctx, value, xpos, ypos, width, height);
	 break;
      default:
         _mesa_problem(ctx, "invalid mode in _swrast_Accum()");
         break;
   }

   RENDER_FINISH(swrast, ctx);
}