s_span.c

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

   }

   /* Stencil and Z testing */
   if (ctx->Stencil.Enabled || ctx->Depth.Test) {
      if (!(span->arrayMask & SPAN_Z))
         _swrast_span_interpolate_z(ctx, span);

      if (ctx->Stencil.Enabled && fb->Visual.stencilBits > 0) {
         /* Combined Z/stencil tests */
         if (!_swrast_stencil_and_ztest_span(ctx, span)) {
            goto end;
         }
      }
      else if (fb->Visual.depthBits > 0) {
         /* Just regular depth testing */
         ASSERT(ctx->Depth.Test);
         ASSERT(span->arrayMask & SPAN_Z);
         if (!_swrast_depth_test_span(ctx, span)) {
            goto end;
         }
      }
   }

#if FEATURE_ARB_occlusion_query
   if (ctx->Query.CurrentOcclusionObject) {
      /* update count of 'passed' fragments */
      struct gl_query_object *q = ctx->Query.CurrentOcclusionObject;
      GLuint i;
      for (i = 0; i < span->end; i++)
         q->Result += span->array->mask[i];
   }
#endif

   /* We had to wait until now to check for glColorMask(0,0,0,0) because of
    * the occlusion test.
    */
   if (colorMask == 0x0) {
      goto end;
   }

   /* If we were able to defer fragment color computation to now, there's
    * a good chance that many fragments will have already been killed by
    * Z/stencil testing.
    */
   if (shaderOrTexture && swrast->_DeferredTexture) {
      shade_texture_span(ctx, span);
   }

#if CHAN_BITS == 32
   if ((span->arrayAttribs & FRAG_BIT_COL0) == 0) {
      interpolate_active_attribs(ctx, span, FRAG_BIT_COL0);
   }
#else
   if ((span->arrayMask & SPAN_RGBA) == 0) {
      interpolate_int_colors(ctx, span);
   }
#endif

   ASSERT(span->arrayMask & SPAN_RGBA);

   if (!shader) {
      /* Add base and specular colors */
      if (ctx->Fog.ColorSumEnabled ||
          (ctx->Light.Enabled &&
           ctx->Light.Model.ColorControl == GL_SEPARATE_SPECULAR_COLOR)) {
         add_specular(ctx, span);
      }
   }

   /* Fog */
   if (swrast->_FogEnabled) {
      _swrast_fog_rgba_span(ctx, span);
   }

   /* Antialias coverage application */
   if (span->arrayMask & SPAN_COVERAGE) {
      apply_aa_coverage(span);
   }

   /* Clamp color/alpha values over the range [0.0, 1.0] before storage */
   if (ctx->Color.ClampFragmentColor == GL_TRUE &&
       span->array->ChanType == GL_FLOAT) {
      clamp_colors(span);
   }

   /*
    * Write to renderbuffers
    */
   {
      const GLuint numBuffers = fb->_NumColorDrawBuffers;
      const GLboolean multiFragOutputs = numBuffers > 1;
      GLuint buf;

      for (buf = 0; buf < numBuffers; buf++) {
         struct gl_renderbuffer *rb = fb->_ColorDrawBuffers[buf];

         /* color[fragOutput] will be written to buffer[buf] */

         if (rb) {
            GLchan rgbaSave[MAX_WIDTH][4];
            const GLuint fragOutput = multiFragOutputs ? buf : 0;

            if (rb->DataType != span->array->ChanType || fragOutput > 0) {
               convert_color_type(span, rb->DataType, fragOutput);
            }

            if (!multiFragOutputs && numBuffers > 1) {
               /* save colors for second, third renderbuffer writes */
               _mesa_memcpy(rgbaSave, span->array->rgba,
                            4 * span->end * sizeof(GLchan));
            }

            ASSERT(rb->_BaseFormat == GL_RGBA || rb->_BaseFormat == GL_RGB);

            if (ctx->Color._LogicOpEnabled) {
               _swrast_logicop_rgba_span(ctx, rb, span);
            }
            else if (ctx->Color.BlendEnabled) {
               _swrast_blend_span(ctx, rb, span);
            }

            if (colorMask != 0xffffffff) {
               _swrast_mask_rgba_span(ctx, rb, span);
            }

            if (span->arrayMask & SPAN_XY) {
               /* array of pixel coords */
               ASSERT(rb->PutValues);
               rb->PutValues(ctx, rb, span->end,
                             span->array->x, span->array->y,
                             span->array->rgba, span->array->mask);
            }
            else {
               /* horizontal run of pixels */
               ASSERT(rb->PutRow);
               rb->PutRow(ctx, rb, span->end, span->x, span->y,
                          span->array->rgba,
                          span->writeAll ? NULL: span->array->mask);
            }

            if (!multiFragOutputs && numBuffers > 1) {
               /* restore original span values */
               _mesa_memcpy(span->array->rgba, rgbaSave,
                            4 * span->end * sizeof(GLchan));
            }

         } /* if rb */
      } /* for buf */
   }

end:
   /* restore these values before returning */
   span->interpMask = origInterpMask;
   span->arrayMask = origArrayMask;
   span->arrayAttribs = origArrayAttribs;
   span->array->ChanType = origChanType;
   span->array->rgba = origRgba;
}


/**
 * Read RGBA pixels from a renderbuffer.  Clipping will be done to prevent
 * reading ouside the buffer's boundaries.
 * \param dstType  datatype for returned colors
 * \param rgba  the returned colors
 */
void
_swrast_read_rgba_span( GLcontext *ctx, struct gl_renderbuffer *rb,
                        GLuint n, GLint x, GLint y, GLenum dstType,
                        GLvoid *rgba)
{
   const GLint bufWidth = (GLint) rb->Width;
   const GLint bufHeight = (GLint) rb->Height;

   if (y < 0 || y >= bufHeight || x + (GLint) n < 0 || x >= bufWidth) {
      /* completely above, below, or right */
      /* XXX maybe leave rgba values undefined? */
      _mesa_bzero(rgba, 4 * n * sizeof(GLchan));
   }
   else {
      GLint skip, length;
      if (x < 0) {
         /* left edge clipping */
         skip = -x;
         length = (GLint) n - skip;
         if (length < 0) {
            /* completely left of window */
            return;
         }
         if (length > bufWidth) {
            length = bufWidth;
         }
      }
      else if ((GLint) (x + n) > bufWidth) {
         /* right edge clipping */
         skip = 0;
         length = bufWidth - x;
         if (length < 0) {
            /* completely to right of window */
            return;
         }
      }
      else {
         /* no clipping */
         skip = 0;
         length = (GLint) n;
      }

      ASSERT(rb);
      ASSERT(rb->GetRow);
      ASSERT(rb->_BaseFormat == GL_RGB || rb->_BaseFormat == GL_RGBA);

      if (rb->DataType == dstType) {
         rb->GetRow(ctx, rb, length, x + skip, y,
                    (GLubyte *) rgba + skip * RGBA_PIXEL_SIZE(rb->DataType));
      }
      else {
         GLuint temp[MAX_WIDTH * 4];
         rb->GetRow(ctx, rb, length, x + skip, y, temp);
         _mesa_convert_colors(rb->DataType, temp,
                   dstType, (GLubyte *) rgba + skip * RGBA_PIXEL_SIZE(dstType),
                   length, NULL);
      }
   }
}


/**
 * Read CI pixels from a renderbuffer.  Clipping will be done to prevent
 * reading ouside the buffer's boundaries.
 */
void
_swrast_read_index_span( GLcontext *ctx, struct gl_renderbuffer *rb,
                         GLuint n, GLint x, GLint y, GLuint index[] )
{
   const GLint bufWidth = (GLint) rb->Width;
   const GLint bufHeight = (GLint) rb->Height;

   if (y < 0 || y >= bufHeight || x + (GLint) n < 0 || x >= bufWidth) {
      /* completely above, below, or right */
      _mesa_bzero(index, n * sizeof(GLuint));
   }
   else {
      GLint skip, length;
      if (x < 0) {
         /* left edge clipping */
         skip = -x;
         length = (GLint) n - skip;
         if (length < 0) {
            /* completely left of window */
            return;
         }
         if (length > bufWidth) {
            length = bufWidth;
         }
      }
      else if ((GLint) (x + n) > bufWidth) {
         /* right edge clipping */
         skip = 0;
         length = bufWidth - x;
         if (length < 0) {
            /* completely to right of window */
            return;
         }
      }
      else {
         /* no clipping */
         skip = 0;
         length = (GLint) n;
      }

      ASSERT(rb->GetRow);
      ASSERT(rb->_BaseFormat == GL_COLOR_INDEX);

      if (rb->DataType == GL_UNSIGNED_BYTE) {
         GLubyte index8[MAX_WIDTH];
         GLint i;
         rb->GetRow(ctx, rb, length, x + skip, y, index8);
         for (i = 0; i < length; i++)
            index[skip + i] = index8[i];
      }
      else if (rb->DataType == GL_UNSIGNED_SHORT) {
         GLushort index16[MAX_WIDTH];
         GLint i;
         rb->GetRow(ctx, rb, length, x + skip, y, index16);
         for (i = 0; i < length; i++)
            index[skip + i] = index16[i];
      }
      else if (rb->DataType == GL_UNSIGNED_INT) {
         rb->GetRow(ctx, rb, length, x + skip, y, index + skip);
      }
   }
}


/**
 * Wrapper for gl_renderbuffer::GetValues() which does clipping to avoid
 * reading values outside the buffer bounds.
 * We can use this for reading any format/type of renderbuffer.
 * \param valueSize is the size in bytes of each value (pixel) put into the
 *                  values array.
 */
void
_swrast_get_values(GLcontext *ctx, struct gl_renderbuffer *rb,
                   GLuint count, const GLint x[], const GLint y[],
                   void *values, GLuint valueSize)
{
   GLuint i, inCount = 0, inStart = 0;

   for (i = 0; i < count; i++) {
      if (x[i] >= 0 && y[i] >= 0 &&
	  x[i] < (GLint) rb->Width && y[i] < (GLint) rb->Height) {
         /* inside */
         if (inCount == 0)
            inStart = i;
         inCount++;
      }
      else {
         if (inCount > 0) {
            /* read [inStart, inStart + inCount) */
            rb->GetValues(ctx, rb, inCount, x + inStart, y + inStart,
                          (GLubyte *) values + inStart * valueSize);
            inCount = 0;
         }
      }
   }
   if (inCount > 0) {
      /* read last values */
      rb->GetValues(ctx, rb, inCount, x + inStart, y + inStart,
                    (GLubyte *) values + inStart * valueSize);
   }
}


/**
 * Wrapper for gl_renderbuffer::PutRow() which does clipping.
 * \param valueSize  size of each value (pixel) in bytes
 */
void
_swrast_put_row(GLcontext *ctx, struct gl_renderbuffer *rb,
                GLuint count, GLint x, GLint y,
                const GLvoid *values, GLuint valueSize)
{
   GLint skip = 0;

   if (y < 0 || y >= (GLint) rb->Height)
      return; /* above or below */

   if (x + (GLint) count <= 0 || x >= (GLint) rb->Width)
      return; /* entirely left or right */

   if ((GLint) (x + count) > (GLint) rb->Width) {
      /* right clip */
      GLint clip = x + count - rb->Width;
      count -= clip;
   }

   if (x < 0) {
      /* left clip */
      skip = -x;
      x = 0;
      count -= skip;
   }

   rb->PutRow(ctx, rb, count, x, y,
              (const GLubyte *) values + skip * valueSize, NULL);
}


/**
 * Wrapper for gl_renderbuffer::GetRow() which does clipping.
 * \param valueSize  size of each value (pixel) in bytes
 */
void
_swrast_get_row(GLcontext *ctx, struct gl_renderbuffer *rb,
                GLuint count, GLint x, GLint y,
                GLvoid *values, GLuint valueSize)
{
   GLint skip = 0;

   if (y < 0 || y >= (GLint) rb->Height)
      return; /* above or below */

   if (x + (GLint) count <= 0 || x >= (GLint) rb->Width)
      return; /* entirely left or right */

   if (x + count > rb->Width) {
      /* right clip */
      GLint clip = x + count - rb->Width;
      count -= clip;
   }

   if (x < 0) {
      /* left clip */
      skip = -x;
      x = 0;
      count -= skip;
   }

   rb->GetRow(ctx, rb, count, x, y, (GLubyte *) values + skip * valueSize);
}


/**
 * Get RGBA pixels from the given renderbuffer.  Put the pixel colors into
 * the span's specular color arrays.  The specular color arrays should no
 * longer be needed by time this function is called.
 * Used by blending, logicop and masking functions.
 * \return pointer to the colors we read.
 */
void *
_swrast_get_dest_rgba(GLcontext *ctx, struct gl_renderbuffer *rb,
                      SWspan *span)
{
   const GLuint pixelSize = RGBA_PIXEL_SIZE(span->array->ChanType);
   void *rbPixels;

   /*
    * Point rbPixels to a temporary space (use specular color arrays).
    */
   rbPixels = span->array->attribs[FRAG_ATTRIB_COL1];

   /* Get destination values from renderbuffer */
   if (span->arrayMask & SPAN_XY) {
      _swrast_get_values(ctx, rb, span->end, span->array->x, span->array->y,
                         rbPixels, pixelSize);
   }
   else {
      _swrast_get_row(ctx, rb, span->end, span->x, span->y,
                      rbPixels, pixelSize);
   }

   return rbPixels;
}