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* Mesa 3-D graphics library
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* Copyright (C) 1999-2007 Brian Paul All Rights Reserved.
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* Permission is hereby granted, free of charge, to any person obtaining a
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* copy of this software and associated documentation files (the "Software"),
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* to deal in the Software without restriction, including without limitation
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* the rights to use, copy, modify, merge, publish, distribute, sublicense,
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* and/or sell copies of the Software, and to permit persons to whom the
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* Software is furnished to do so, subject to the following conditions:
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
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* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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* BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
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* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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#include "main/glheader.h"
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#include "main/colormac.h"
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#include "main/feedback.h"
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#include "main/formats.h"
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#include "main/image.h"
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#include "main/imports.h"
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#include "main/macros.h"
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#include "main/pack.h"
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#include "main/state.h"
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#include "s_context.h"
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#include "s_stencil.h"
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* Read pixels for format=GL_DEPTH_COMPONENT.
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read_depth_pixels( struct gl_context *ctx,
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GLsizei width, GLsizei height,
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GLenum type, GLvoid *pixels,
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const struct gl_pixelstore_attrib *packing )
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struct gl_framebuffer *fb = ctx->ReadBuffer;
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struct gl_renderbuffer *rb = fb->_DepthBuffer;
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const GLboolean biasOrScale
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= ctx->Pixel.DepthScale != 1.0 || ctx->Pixel.DepthBias != 0.0;
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/* clipping should have been done already */
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ASSERT(x + width <= (GLint) rb->Width);
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ASSERT(y + height <= (GLint) rb->Height);
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/* width should never be > MAX_WIDTH since we did clipping earlier */
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ASSERT(width <= MAX_WIDTH);
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if (type == GL_UNSIGNED_SHORT && fb->Visual.depthBits == 16
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&& !biasOrScale && !packing->SwapBytes) {
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/* Special case: directly read 16-bit unsigned depth values. */
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ASSERT(rb->Format == MESA_FORMAT_Z16);
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ASSERT(rb->DataType == GL_UNSIGNED_SHORT);
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for (j = 0; j < height; j++, y++) {
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void *dest =_mesa_image_address2d(packing, pixels, width, height,
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GL_DEPTH_COMPONENT, type, j, 0);
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rb->GetRow(ctx, rb, width, x, y, dest);
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else if (type == GL_UNSIGNED_INT && fb->Visual.depthBits == 24
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&& !biasOrScale && !packing->SwapBytes) {
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/* Special case: directly read 24-bit unsigned depth values. */
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ASSERT(rb->Format == MESA_FORMAT_X8_Z24 ||
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rb->Format == MESA_FORMAT_S8_Z24 ||
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rb->Format == MESA_FORMAT_Z24_X8 ||
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rb->Format == MESA_FORMAT_Z24_S8);
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ASSERT(rb->DataType == GL_UNSIGNED_INT ||
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rb->DataType == GL_UNSIGNED_INT_24_8);
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for (j = 0; j < height; j++, y++) {
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GLuint *dest = (GLuint *)
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_mesa_image_address2d(packing, pixels, width, height,
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GL_DEPTH_COMPONENT, type, j, 0);
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rb->GetRow(ctx, rb, width, x, y, dest);
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/* convert range from 24-bit to 32-bit */
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if (rb->Format == MESA_FORMAT_X8_Z24 ||
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rb->Format == MESA_FORMAT_S8_Z24) {
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for (k = 0; k < width; k++) {
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/* Note: put MSByte of 24-bit value into LSByte */
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dest[k] = (dest[k] << 8) | ((dest[k] >> 16) & 0xff);
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for (k = 0; k < width; k++) {
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/* Note: fill in LSByte by replication */
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dest[k] = dest[k] | ((dest[k] >> 8) & 0xff);
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else if (type == GL_UNSIGNED_INT && fb->Visual.depthBits == 32
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&& !biasOrScale && !packing->SwapBytes) {
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/* Special case: directly read 32-bit unsigned depth values. */
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ASSERT(rb->Format == MESA_FORMAT_Z32);
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ASSERT(rb->DataType == GL_UNSIGNED_INT);
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for (j = 0; j < height; j++, y++) {
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void *dest = _mesa_image_address2d(packing, pixels, width, height,
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GL_DEPTH_COMPONENT, type, j, 0);
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rb->GetRow(ctx, rb, width, x, y, dest);
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/* General case (slower) */
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for (j = 0; j < height; j++, y++) {
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GLfloat depthValues[MAX_WIDTH];
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GLvoid *dest = _mesa_image_address2d(packing, pixels, width, height,
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GL_DEPTH_COMPONENT, type, j, 0);
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_swrast_read_depth_span_float(ctx, rb, width, x, y, depthValues);
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_mesa_pack_depth_span(ctx, width, dest, type, depthValues, packing);
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* Read pixels for format=GL_STENCIL_INDEX.
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read_stencil_pixels( struct gl_context *ctx,
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GLsizei width, GLsizei height,
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GLenum type, GLvoid *pixels,
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const struct gl_pixelstore_attrib *packing )
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struct gl_framebuffer *fb = ctx->ReadBuffer;
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struct gl_renderbuffer *rb = fb->_StencilBuffer;
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/* width should never be > MAX_WIDTH since we did clipping earlier */
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ASSERT(width <= MAX_WIDTH);
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/* process image row by row */
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for (j=0;j<height;j++,y++) {
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GLstencil stencil[MAX_WIDTH];
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_swrast_read_stencil_span(ctx, rb, width, x, y, stencil);
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dest = _mesa_image_address2d(packing, pixels, width, height,
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GL_STENCIL_INDEX, type, j, 0);
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_mesa_pack_stencil_span(ctx, width, type, dest, stencil, packing);
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* Optimized glReadPixels for particular pixel formats when pixel
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* scaling, biasing, mapping, etc. are disabled.
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* \return GL_TRUE if success, GL_FALSE if unable to do the readpixels
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fast_read_rgba_pixels( struct gl_context *ctx,
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GLsizei width, GLsizei height,
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GLenum format, GLenum type,
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const struct gl_pixelstore_attrib *packing,
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GLbitfield transferOps)
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struct gl_renderbuffer *rb = ctx->ReadBuffer->_ColorReadBuffer;
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ASSERT(rb->_BaseFormat == GL_RGBA ||
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rb->_BaseFormat == GL_RGB ||
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rb->_BaseFormat == GL_RG ||
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rb->_BaseFormat == GL_RED ||
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rb->_BaseFormat == GL_LUMINANCE ||
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rb->_BaseFormat == GL_INTENSITY ||
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rb->_BaseFormat == GL_LUMINANCE_ALPHA ||
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rb->_BaseFormat == GL_ALPHA);
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/* clipping should have already been done */
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ASSERT(x + width <= (GLint) rb->Width);
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ASSERT(y + height <= (GLint) rb->Height);
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/* check for things we can't handle here */
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packing->SwapBytes ||
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if (format == GL_RGBA && rb->DataType == type) {
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const GLint dstStride = _mesa_image_row_stride(packing, width,
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= (GLubyte *) _mesa_image_address2d(packing, pixels, width, height,
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for (row = 0; row < height; row++) {
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rb->GetRow(ctx, rb, width, x, y + row, dest);
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if (format == GL_RGB &&
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rb->DataType == GL_UNSIGNED_BYTE &&
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type == GL_UNSIGNED_BYTE) {
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const GLint dstStride = _mesa_image_row_stride(packing, width,
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= (GLubyte *) _mesa_image_address2d(packing, pixels, width, height,
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for (row = 0; row < height; row++) {
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GLubyte tempRow[MAX_WIDTH][4];
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rb->GetRow(ctx, rb, width, x, y + row, tempRow);
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/* convert RGBA to RGB */
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for (col = 0; col < width; col++) {
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dest[col * 3 + 0] = tempRow[col][0];
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dest[col * 3 + 1] = tempRow[col][1];
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dest[col * 3 + 2] = tempRow[col][2];
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* When we're using a low-precision color buffer (like 16-bit 5/6/5)
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* we have to adjust our color values a bit to pass conformance.
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* The problem is when a 5 or 6-bit color value is converted to an 8-bit
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* value and then a floating point value, the floating point values don't
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* increment uniformly as the 5 or 6-bit value is incremented.
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* This function adjusts floating point values to compensate.
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adjust_colors(const struct gl_framebuffer *fb, GLuint n, GLfloat rgba[][4])
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const GLuint rShift = 8 - fb->Visual.redBits;
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const GLuint gShift = 8 - fb->Visual.greenBits;
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const GLuint bShift = 8 - fb->Visual.blueBits;
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GLfloat rScale = 1.0F / (GLfloat) ((1 << fb->Visual.redBits ) - 1);
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GLfloat gScale = 1.0F / (GLfloat) ((1 << fb->Visual.greenBits) - 1);
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GLfloat bScale = 1.0F / (GLfloat) ((1 << fb->Visual.blueBits ) - 1);
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if (fb->Visual.redBits == 0)
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if (fb->Visual.greenBits == 0)
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if (fb->Visual.blueBits == 0)
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for (i = 0; i < n; i++) {
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/* convert float back to ubyte */
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CLAMPED_FLOAT_TO_UBYTE(r, rgba[i][RCOMP]);
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CLAMPED_FLOAT_TO_UBYTE(g, rgba[i][GCOMP]);
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CLAMPED_FLOAT_TO_UBYTE(b, rgba[i][BCOMP]);
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/* using only the N most significant bits of the ubyte value, convert to
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rgba[i][RCOMP] = (GLfloat) (r >> rShift) * rScale;
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rgba[i][GCOMP] = (GLfloat) (g >> gShift) * gScale;
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rgba[i][BCOMP] = (GLfloat) (b >> bShift) * bScale;
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* Read R, G, B, A, RGB, L, or LA pixels.
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read_rgba_pixels( struct gl_context *ctx,
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GLsizei width, GLsizei height,
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GLenum format, GLenum type, GLvoid *pixels,
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const struct gl_pixelstore_attrib *packing )
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SWcontext *swrast = SWRAST_CONTEXT(ctx);
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GLbitfield transferOps = ctx->_ImageTransferState;
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struct gl_framebuffer *fb = ctx->ReadBuffer;
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struct gl_renderbuffer *rb = fb->_ColorReadBuffer;
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if ((ctx->Color._ClampReadColor == GL_TRUE || type != GL_FLOAT) &&
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!_mesa_is_integer_format(format)) {
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transferOps |= IMAGE_CLAMP_BIT;
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/* Try the optimized path first. */
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if (fast_read_rgba_pixels(ctx, x, y, width, height,
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format, type, pixels, packing, transferOps)) {
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/* width should never be > MAX_WIDTH since we did clipping earlier */
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ASSERT(width <= MAX_WIDTH);
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const GLint dstStride
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= _mesa_image_row_stride(packing, width, format, type);
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GLfloat (*rgba)[4] = swrast->SpanArrays->attribs[FRAG_ATTRIB_COL0];
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= (GLubyte *) _mesa_image_address2d(packing, pixels, width, height,
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for (row = 0; row < height; row++, y++) {
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/* Get float rgba pixels */
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_swrast_read_rgba_span(ctx, rb, width, x, y, GL_FLOAT, rgba);
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/* apply fudge factor for shallow color buffers */
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if ((fb->Visual.redBits < 8 && fb->Visual.redBits != 0) ||
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(fb->Visual.greenBits < 8 && fb->Visual.greenBits != 0) ||
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(fb->Visual.blueBits < 8 && fb->Visual.blueBits != 0)) {
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adjust_colors(fb, width, rgba);
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/* pack the row of RGBA pixels into user's buffer */
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_mesa_pack_rgba_span_float(ctx, width, rgba, format, type, dst,
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packing, transferOps);
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* Read combined depth/stencil values.
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* We'll have already done error checking to be sure the expected
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* depth and stencil buffers really exist.
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read_depth_stencil_pixels(struct gl_context *ctx,
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GLsizei width, GLsizei height,
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GLenum type, GLvoid *pixels,
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const struct gl_pixelstore_attrib *packing )
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const GLboolean scaleOrBias
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= ctx->Pixel.DepthScale != 1.0 || ctx->Pixel.DepthBias != 0.0;
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const GLboolean stencilTransfer = ctx->Pixel.IndexShift
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|| ctx->Pixel.IndexOffset || ctx->Pixel.MapStencilFlag;
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struct gl_renderbuffer *depthRb, *stencilRb;
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depthRb = ctx->ReadBuffer->_DepthBuffer;
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stencilRb = ctx->ReadBuffer->_StencilBuffer;
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if (!depthRb || !stencilRb)
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depthRb = ctx->ReadBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
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stencilRb = ctx->ReadBuffer->Attachment[BUFFER_STENCIL].Renderbuffer;
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if (depthRb->_BaseFormat == GL_DEPTH_STENCIL_EXT &&
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stencilRb->_BaseFormat == GL_DEPTH_STENCIL_EXT &&
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depthRb == stencilRb &&
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/* This is the ideal case.
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* Reading GL_DEPTH_STENCIL pixels from combined depth/stencil buffer.
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* Plus, no pixel transfer ops to worry about!
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GLint dstStride = _mesa_image_row_stride(packing, width,
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GL_DEPTH_STENCIL_EXT, type);
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GLubyte *dst = (GLubyte *) _mesa_image_address2d(packing, pixels,
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GL_DEPTH_STENCIL_EXT,
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for (i = 0; i < height; i++) {
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depthRb->GetRow(ctx, depthRb, width, x, y + i, dst);
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/* Reading GL_DEPTH_STENCIL pixels from separate depth/stencil buffers,
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* or we need pixel transfer.
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depthRb = ctx->ReadBuffer->_DepthBuffer;
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stencilRb = ctx->ReadBuffer->_StencilBuffer;
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for (i = 0; i < height; i++) {
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GLstencil stencilVals[MAX_WIDTH];
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GLuint *depthStencilDst = (GLuint *)
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_mesa_image_address2d(packing, pixels, width, height,
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GL_DEPTH_STENCIL_EXT, type, i, 0);
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_swrast_read_stencil_span(ctx, stencilRb, width,
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x, y + i, stencilVals);
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if (!scaleOrBias && !stencilTransfer
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&& ctx->ReadBuffer->Visual.depthBits == 24) {
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GLuint zVals[MAX_WIDTH]; /* 24-bit values! */
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ASSERT(depthRb->DataType == GL_UNSIGNED_INT);
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/* note, we've already been clipped */
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depthRb->GetRow(ctx, depthRb, width, x, y + i, zVals);
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for (j = 0; j < width; j++) {
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depthStencilDst[j] = (zVals[j] << 8) | (stencilVals[j] & 0xff);
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GLfloat depthVals[MAX_WIDTH];
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_swrast_read_depth_span_float(ctx, depthRb, width, x, y + i,
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_mesa_pack_depth_stencil_span(ctx, width, depthStencilDst,
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depthVals, stencilVals, packing);
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* Software fallback routine for ctx->Driver.ReadPixels().
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* By time we get here, all error checking will have been done.
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_swrast_ReadPixels( struct gl_context *ctx,
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GLint x, GLint y, GLsizei width, GLsizei height,
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GLenum format, GLenum type,
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const struct gl_pixelstore_attrib *packing,
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SWcontext *swrast = SWRAST_CONTEXT(ctx);
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struct gl_pixelstore_attrib clippedPacking = *packing;
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_mesa_update_state(ctx);
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/* Need to do swrast_render_start() before clipping or anything else
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* since this is where a driver may grab the hw lock and get an updated
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swrast_render_start(ctx);
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if (swrast->NewState)
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_swrast_validate_derived( ctx );
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/* Do all needed clipping here, so that we can forget about it later */
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if (_mesa_clip_readpixels(ctx, &x, &y, &width, &height, &clippedPacking)) {
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pixels = _mesa_map_pbo_dest(ctx, &clippedPacking, pixels);
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case GL_STENCIL_INDEX:
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read_stencil_pixels(ctx, x, y, width, height, type, pixels,
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case GL_DEPTH_COMPONENT:
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read_depth_pixels(ctx, x, y, width, height, type, pixels,
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case GL_DEPTH_STENCIL_EXT:
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read_depth_stencil_pixels(ctx, x, y, width, height, type, pixels,
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/* all other formats should be color formats */
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read_rgba_pixels(ctx, x, y, width, height, format, type, pixels,
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_mesa_unmap_pbo_dest(ctx, &clippedPacking);
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swrast_render_finish(ctx);