On 31.10.2016 22:52, Nicolai Hähnle wrote:
From: Nicolai Hähnle <[email protected]>
The first two vertices are swapped for triangle strips with adjacency; see
Table 10.1 of the OpenGL 4.5 (Compatibility Profile) spec.
FWIW, people report that the test passes as-is on NVidia hardware (both
nouveau and blob) but fails on various Intel hardware.
I ran across this because radeonsi used to pass the test as-is, but now
that I've added a fix for how our hardware rotates the odd triangles we
started failing it (in the same way as Intel):
$ bin/gl-3.2-adj-prims pv-first -auto -fbo
Failure for GL_TRIANGLE_STRIP_ADJACENCY, prim 1 wrong color at (641,108)
Expected 0.2, 0.2, 1, 1
Found 0.2, 1, 1, 1
PIGLIT: {"result": "fail" }
My reading of the spec is that the GS invocation for the second triangle
should have vs_gs_color[0] sourced from colors[4] instead of colors[2]
as the test expects, and then this becomes the color of the first vertex
and hence the color of the provoking vertex in this particular subtest.
(And I guess this explanation should go into the commit message if
people agree that this change is correct.)
Cheers,
Nicolai
---
tests/spec/gl-3.2/adj-prims.c | 18 +++++++++++++-----
1 file changed, 13 insertions(+), 5 deletions(-)
diff --git a/tests/spec/gl-3.2/adj-prims.c b/tests/spec/gl-3.2/adj-prims.c
index 9d2f121..30c5f4b 100644
--- a/tests/spec/gl-3.2/adj-prims.c
+++ b/tests/spec/gl-3.2/adj-prims.c
@@ -166,23 +166,26 @@ provoking_vertex_index(GLenum prim_mode, GLenum pv_mode,
unsigned prim_index)
if (pv_mode == GL_FIRST_VERTEX_CONVENTION)
return prim_index + 1;
else
return prim_index + 2;
case GL_TRIANGLES_ADJACENCY:
if (pv_mode == GL_FIRST_VERTEX_CONVENTION)
return prim_index * 6 + 0;
else
return prim_index * 6 + 4;
case GL_TRIANGLE_STRIP_ADJACENCY:
- if (pv_mode == GL_FIRST_VERTEX_CONVENTION)
- return prim_index * 2;
- else
+ if (pv_mode == GL_FIRST_VERTEX_CONVENTION) {
+ if (prim_index & 1)
+ return prim_index * 2 + 2;
+ else
+ return prim_index * 2;
+ } else
return prim_index * 2 + 4;
default:
assert(!"Unexpected prim_mode");
return 0;
}
}
/**
* Given a primitive type and a primitive (line/triangle) index, return
@@ -205,22 +208,27 @@ compute_probe_location(GLenum prim_mode, unsigned
prim_index,
i0 = prim_index + 1;
i1 = prim_index + 2;
break;
case GL_TRIANGLES_ADJACENCY:
i0 = prim_index * 6 + 0;
i1 = prim_index * 6 + 2;
if (polygon_mode != GL_LINE)
i2 = prim_index * 6 + 4;
break;
case GL_TRIANGLE_STRIP_ADJACENCY:
- i0 = prim_index * 2;
- i1 = prim_index * 2 + 2;
+ if (prim_index & 1) {
+ i0 = prim_index * 2;
+ i1 = prim_index * 2 + 2;
+ } else {
+ i0 = prim_index * 2 + 2;
+ i1 = prim_index * 2;
+ }
if (polygon_mode != GL_LINE)
i2 = prim_index * 2 + 4;
break;
default:
assert(!"Unexpected prim_mode");
*x = *y = 0;
return;
}
/* average of 2 or 3 points */
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