Broken with
e5c6a92a12b5cd7db205d72039f58d302b0be9d5. (ARB_color_buffer_float)
Clamping should occur if type != float, otherwise the MSBs of the resulting
pixels are killed off. For example, reading back LUMINANCE = R+G+B can be
greater than 0xff, but the result is naturally masked by 0xff
for UNSIGNED_BYTE, leading to bogus results.
The following bug report seems to want clamping to occur if type == half_float
too. Not sure what's correct.
Bug: [bisected pineview] oglc case pxconv-read failed
https://bugs.freedesktop.org/show_bug.cgi?id=35852
Tested by: Fang Xun <xunx.fang@intel.com>
Reviewed-and-tested-by: Ian Romanick <ian.d.romanick@intel.com>
if (!rb)
return;
- if (type == GL_FLOAT && ((ctx->Color.ClampReadColor == GL_TRUE) ||
- (ctx->Color.ClampReadColor == GL_FIXED_ONLY_ARB &&
- rb->DataType != GL_FLOAT)))
+ if ((ctx->Color._ClampReadColor == GL_TRUE || type != GL_FLOAT) &&
+ !_mesa_is_integer_format(format)) {
transferOps |= IMAGE_CLAMP_BIT;
+ }
- /* Try optimized path first */
+ /* Try the optimized path first. */
if (fast_read_rgba_pixels(ctx, x, y, width, height,
format, type, pixels, packing, transferOps)) {
return; /* done! */