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i915g: fix incorrect gl_FragCoord value

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On Intel Pineview M hardware, the i915 gallium driver doesn't output
the correct gl_FragCoord. It seems to always have an X coord of 0.0
and a Y coord of the window's height in pixels, e.g. 600.0f or such.

I believe this is a regression caused in part by this commit:
afa035031f

The old behavior used the output at index zero, while the new behavior
uses actual zeroes. In the case of gl_FragCoord the output at index
zero happened to be the correct one, so the behavior appeared correct
although the code already had a bug.

Fixed by checking for I915_SEMANTIC_POS when setting up texCoords. If
the generic_mapping is I915_SEMANTIC_POS, look for the
TGSI_SEMANTIC_POSITION instead of a TGSI_SEMANTIC_GENERIC output.

https://bugs.freedesktop.org/show_bug.cgi?id=97477

Reviewed-by: Stéphane Marchesin <marcheu@chromium.org>
Tested-by: Stéphane Marchesin <marcheu@chromium.org>
This commit is contained in:
Nicholas Bishop
2016-08-25 19:31:53 -04:00
committed by Stéphane Marchesin
parent c10dcb2ce8
commit 64435fd888
1 changed files with 6 additions and 1 deletions
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src/gallium/drivers/i915/i915_state_derived.c
+6 -1
View File
@@ -145,7 +145,12 @@ static void calculate_vertex_layout(struct i915_context *i915)
uint hwtc;
if (texCoords[i]) {
hwtc = TEXCOORDFMT_4D;
src = draw_find_shader_output(i915->draw, TGSI_SEMANTIC_GENERIC, fs->generic_mapping[i]);
if (fs->generic_mapping[i] == I915_SEMANTIC_POS) {
src = draw_find_shader_output(i915->draw, TGSI_SEMANTIC_POSITION, 0);
}
else {
src = draw_find_shader_output(i915->draw, TGSI_SEMANTIC_GENERIC, fs->generic_mapping[i]);
}
draw_emit_vertex_attr(&vinfo, EMIT_4F, src);
}
else {