Generate flat triangles in polygon offset tests.

The tests setup triangles with a depth slope and then call
glPolygonOffset(factor, units) with variable units and
always 0 slope scaled factor.

According to the GLES 3.2 spec 13.7.2 Depth Offset:
"void PolygonOffset( float factor, float units );
factor scales the maximum depth slope of the polygon, and units scales an
implementation-dependent constant that relates to the usable resolution of the
depth buffer."

If the polygon has a depth slope,
the depth slope factor has to be not equal to zero.
The rationale of the slope scaled factor is to ensure that the offset
(equation 13.11) is greater than max(dz/dx, dz/dy) for all resolutions,
which may not be the case for the constant offset since it doesn't take
the screen resolution into account.

Changed tests:

dEQP-GLES2.functional.polygon_offset.*_displacement_with_units
dEQP-GLES3.functional.polygon_offset.*_displacement_with_units

Bug: 34386628

Change-Id: Ie8009ba1766eb50c3c5a750122aa8bb231144210

diff --git a/modules/gles2/functional/es2fPolygonOffsetTests.cpp b/modules/gles2/functional/es2fPolygonOffsetTests.cpp
index 4a933d88dbc02f75ec6c817c07eec0caae8cb890..7ec850f5043eec16bf0e45cfa57926665839cb87 100644 (file)
--- a/modules/gles2/functional/es2fPolygonOffsetTests.cpp
+++ b/modules/gles2/functional/es2fPolygonOffsetTests.cpp
@@ -475,7 +475,7 @@ tcu::Vec4 UsageDisplacementTestCase::genRandomVec4 (de::Random& rnd) const
 
        retVal.x() = rnd.getFloat(-1, 1);
        retVal.y() = rnd.getFloat(-1, 1);
-       retVal.z() = rnd.getFloat(-0.9f, 0.9f);
+       retVal.z() = 0.5f;
        retVal.w() = 1.0f + rnd.getFloat();
 
        return retVal;

diff --git a/modules/gles3/functional/es3fPolygonOffsetTests.cpp b/modules/gles3/functional/es3fPolygonOffsetTests.cpp
index 554539d4492dfe94350173cf70b882968cc1b39c..7352ee621cd734dc92623eaa5550b2e5a97f4d8f 100644 (file)
--- a/modules/gles3/functional/es3fPolygonOffsetTests.cpp
+++ b/modules/gles3/functional/es3fPolygonOffsetTests.cpp
@@ -478,7 +478,7 @@ tcu::Vec4 UsageDisplacementTestCase::genRandomVec4 (de::Random& rnd) const
 
        retVal.x() = rnd.getFloat(-1, 1);
        retVal.y() = rnd.getFloat(-1, 1);
-       retVal.z() = rnd.getFloat(-0.9f, 0.9f);
+       retVal.z() = 0.5f;
        retVal.w() = 1.0f + rnd.getFloat();
 
        return retVal;