s_readpix.c

来自「mesa-6.5-minigui源码」· C语言 代码 · 共 597 行 · 第 1/2 页

      const GLuint transferOps = ctx->_ImageTransferState;
      GLfloat *dest, *src, *tmpImage, *convImage;
      GLint row;

      tmpImage = (GLfloat *) _mesa_malloc(width * height * 4 * sizeof(GLfloat));
      if (!tmpImage) {
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glReadPixels");
         return;
      }
      convImage = (GLfloat *) _mesa_malloc(width * height * 4 * sizeof(GLfloat));
      if (!convImage) {
         _mesa_free(tmpImage);
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "glReadPixels");
         return;
      }

      /* read full RGBA, FLOAT image */
      dest = tmpImage;
      for (row = 0; row < height; row++, y++) {
         GLchan rgba[MAX_WIDTH][4];
         if (fb->Visual.rgbMode) {
            _swrast_read_rgba_span(ctx, rb, width, x, y, rgba);
         }
         else {
            GLuint index[MAX_WIDTH];
            ASSERT(rb->DataType == GL_UNSIGNED_INT);
            rb->GetRow(ctx, rb, width, x, y, index);
            if (ctx->Pixel.IndexShift != 0 || ctx->Pixel.IndexOffset !=0 ) {
               _mesa_map_ci(ctx, width, index);
            }
            _mesa_map_ci_to_rgba_chan(ctx, width, index, rgba);
         }
         _mesa_pack_rgba_span_chan(ctx, width, (const GLchan (*)[4]) rgba,
                              GL_RGBA, GL_FLOAT, dest, &ctx->DefaultPacking,
                              transferOps & IMAGE_PRE_CONVOLUTION_BITS);
         dest += width * 4;
      }

      /* do convolution */
      if (ctx->Pixel.Convolution2DEnabled) {
         _mesa_convolve_2d_image(ctx, &width, &height, tmpImage, convImage);
      }
      else {
         ASSERT(ctx->Pixel.Separable2DEnabled);
         _mesa_convolve_sep_image(ctx, &width, &height, tmpImage, convImage);
      }
      _mesa_free(tmpImage);

      /* finish transfer ops and pack the resulting image */
      src = convImage;
      for (row = 0; row < height; row++) {
         GLvoid *dest;
         dest = _mesa_image_address2d(packing, pixels, width, height,
                                      format, type, row, 0);
         _mesa_pack_rgba_span_float(ctx, width,
                                    (const GLfloat (*)[4]) src,
                                    format, type, dest, packing,
                                    transferOps & IMAGE_POST_CONVOLUTION_BITS);
         src += width * 4;
      }
   }
   else {
      /* no convolution */
      GLint row;
      for (row = 0; row < height; row++, y++) {
         GLchan rgba[MAX_WIDTH][4];
         GLvoid *dst;
         if (fb->Visual.rgbMode) {
            _swrast_read_rgba_span(ctx, rb, width, x, y, rgba);
         }
         else {
            GLuint index[MAX_WIDTH];
            ASSERT(rb->DataType == GL_UNSIGNED_INT);
            rb->GetRow(ctx, rb, width, x, y, index);
            if (ctx->Pixel.IndexShift != 0 || ctx->Pixel.IndexOffset != 0) {
               _mesa_map_ci(ctx, width, index);
            }
            _mesa_map_ci_to_rgba_chan(ctx, width, index, rgba);
         }
         dst = _mesa_image_address2d(packing, pixels, width, height,
                                     format, type, row, 0);
         if (fb->Visual.redBits < CHAN_BITS ||
             fb->Visual.greenBits < CHAN_BITS ||
             fb->Visual.blueBits < CHAN_BITS) {
            /* Requantize the color values into floating point and go from
             * there.  This fixes conformance failures with 16-bit color
             * buffers, for example.
             */
            GLfloat rgbaf[MAX_WIDTH][4];
            _mesa_chan_to_float_span(ctx, width,
                                     (CONST GLchan (*)[4]) rgba, rgbaf);
            _mesa_pack_rgba_span_float(ctx, width,
                                       (CONST GLfloat (*)[4]) rgbaf,
                                       format, type, dst, packing,
                                       ctx->_ImageTransferState);
         }
         else {
            /* GLubytes are fine */
            _mesa_pack_rgba_span_chan(ctx, width, (CONST GLchan (*)[4]) rgba,
                                 format, type, dst, packing,
                                 ctx->_ImageTransferState);
         }
      }
   }
}


/**
 * Read combined depth/stencil values.
 * We'll have already done error checking to be sure the expected
 * depth and stencil buffers really exist.
 */
static void
read_depth_stencil_pixels(GLcontext *ctx,
                          GLint x, GLint y,
                          GLsizei width, GLsizei height,
                          GLenum type, GLvoid *pixels,
                          const struct gl_pixelstore_attrib *packing )
{
   const GLboolean scaleOrBias
      = ctx->Pixel.DepthScale != 1.0 || ctx->Pixel.DepthBias != 0.0;
   const GLboolean stencilTransfer = ctx->Pixel.IndexShift
      || ctx->Pixel.IndexOffset || ctx->Pixel.MapStencilFlag;
   struct gl_renderbuffer *depthRb, *stencilRb;

   depthRb = ctx->ReadBuffer->_DepthBuffer;
   stencilRb = ctx->ReadBuffer->_StencilBuffer;

   ASSERT(depthRb);
   ASSERT(stencilRb);

   depthRb = ctx->ReadBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
   stencilRb = ctx->ReadBuffer->Attachment[BUFFER_STENCIL].Renderbuffer;

   if (depthRb->_BaseFormat == GL_DEPTH_STENCIL_EXT &&
       stencilRb->_BaseFormat == GL_DEPTH_STENCIL_EXT &&
       depthRb == stencilRb &&
       !scaleOrBias &&
       !stencilTransfer) {
      /* This is the ideal case.
       * Reading GL_DEPTH_STENCIL pixels from combined depth/stencil buffer.
       * Plus, no pixel transfer ops to worry about!
       */
      GLint i;
      GLint dstStride = _mesa_image_row_stride(packing, width,
                                               GL_DEPTH_STENCIL_EXT, type);
      GLubyte *dst = (GLubyte *) _mesa_image_address2d(packing, pixels,
                                                       width, height,
                                                       GL_DEPTH_STENCIL_EXT,
                                                       type, 0, 0);
      for (i = 0; i < height; i++) {
         depthRb->GetRow(ctx, depthRb, width, x, y + i, dst);
         dst += dstStride;
      }
   }
   else {
      /* Reading GL_DEPTH_STENCIL pixels from separate depth/stencil buffers,
       * or we need pixel transfer.
       */
      GLint i;
      depthRb = ctx->ReadBuffer->_DepthBuffer;
      stencilRb = ctx->ReadBuffer->_StencilBuffer;

      for (i = 0; i < height; i++) {
         GLstencil stencilVals[MAX_WIDTH];

         GLuint *depthStencilDst = (GLuint *)
            _mesa_image_address2d(packing, pixels, width, height,
                                  GL_DEPTH_STENCIL_EXT, type, i, 0);

         _swrast_read_stencil_span(ctx, stencilRb, width,
                                   x, y + i, stencilVals);

         if (!scaleOrBias && !stencilTransfer
             && ctx->ReadBuffer->Visual.depthBits == 24) {
            /* ideal case */
            GLuint zVals[MAX_WIDTH]; /* 24-bit values! */
            GLint j;
            ASSERT(depthRb->DataType == GL_UNSIGNED_INT);
            /* note, we've already been clipped */
            depthRb->GetRow(ctx, depthRb, width, x, y + i, zVals);
            for (j = 0; j < width; j++) {
               depthStencilDst[j] = (zVals[j] << 8) | (stencilVals[j] & 0xff);
            }
         }
         else {
            /* general case */
            GLfloat depthVals[MAX_WIDTH];
            _swrast_read_depth_span_float(ctx, depthRb, width, x, y + i,
                                          depthVals);
            _mesa_pack_depth_stencil_span(ctx, width, depthStencilDst,
                                          depthVals, stencilVals, packing);
         }
      }
   }
}



/**
 * Software fallback routine for ctx->Driver.ReadPixels().
 * By time we get here, all error checking will have been done.
 */
void
_swrast_ReadPixels( GLcontext *ctx,
		    GLint x, GLint y, GLsizei width, GLsizei height,
		    GLenum format, GLenum type,
		    const struct gl_pixelstore_attrib *packing,
		    GLvoid *pixels )
{
   SWcontext *swrast = SWRAST_CONTEXT(ctx);
   struct gl_pixelstore_attrib clippedPacking = *packing;

   /* Need to do RENDER_START before clipping or anything else since this
    * is where a driver may grab the hw lock and get an updated window
    * size.
    */
   RENDER_START(swrast, ctx);

   if (ctx->NewState)
      _mesa_update_state(ctx);

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

   /* Do all needed clipping here, so that we can forget about it later */
   if (!_mesa_clip_readpixels(ctx, &x, &y, &width, &height, &clippedPacking)) {
      /* The ReadPixels region is totally outside the window bounds */
      return;
   }

   if (clippedPacking.BufferObj->Name) {
      /* pack into PBO */
      GLubyte *buf;
      if (!_mesa_validate_pbo_access(2, &clippedPacking, width, height, 1,
                                     format, type, pixels)) {
         _mesa_error(ctx, GL_INVALID_OPERATION,
                     "glReadPixels(invalid PBO access)");
         goto end;
      }
      buf = (GLubyte *) ctx->Driver.MapBuffer(ctx, GL_PIXEL_PACK_BUFFER_EXT,
                                              GL_WRITE_ONLY_ARB,
                                              clippedPacking.BufferObj);
      if (!buf) {
         /* buffer is already mapped - that's an error */
         _mesa_error(ctx, GL_INVALID_OPERATION, "glReadPixels(PBO is mapped)");
         goto end;
      }
      pixels = ADD_POINTERS(buf, pixels);
   }

   switch (format) {
      case GL_COLOR_INDEX:
         read_index_pixels(ctx, x, y, width, height, type, pixels,
                           &clippedPacking);
	 break;
      case GL_STENCIL_INDEX:
	 read_stencil_pixels(ctx, x, y, width, height, type, pixels,
                             &clippedPacking);
         break;
      case GL_DEPTH_COMPONENT:
	 read_depth_pixels(ctx, x, y, width, height, type, pixels,
                           &clippedPacking);
	 break;
      case GL_RED:
      case GL_GREEN:
      case GL_BLUE:
      case GL_ALPHA:
      case GL_RGB:
      case GL_LUMINANCE:
      case GL_LUMINANCE_ALPHA:
      case GL_RGBA:
      case GL_BGR:
      case GL_BGRA:
      case GL_ABGR_EXT:
         read_rgba_pixels(ctx, x, y, width, height,
                          format, type, pixels, &clippedPacking);
	 break;
      case GL_DEPTH_STENCIL_EXT:
         read_depth_stencil_pixels(ctx, x, y, width, height,
                                   type, pixels, &clippedPacking);
         break;
      default:
	 _mesa_problem(ctx, "unexpected format in _swrast_ReadPixels");
         /* don't return yet, clean-up */
   }


end:
   RENDER_FINISH(swrast, ctx);

   if (clippedPacking.BufferObj->Name) {
      /* done with PBO so unmap it now */
      ctx->Driver.UnmapBuffer(ctx, GL_PIXEL_PACK_BUFFER_EXT,
                              clippedPacking.BufferObj);
   }
}