Improve existing cull distance tests

Previously the tests were just writing a constant value to
gl_CullDistance[i] in the vertex shader and copying that value in
the rest of the geometry stages.

This commit does the following:

- The last shader writting to gl_CullDistance assigns 0 if
gl_Position.y < 0 and 0.5f otherwise. That way we can test the
interpolation of gl_CullDistance in the fragment shader.

- In case there are multiple geometry shaders, all except the last one
write a different value to gl_CullDistance[i] and checks the value
written by the previous shader stage. Therefore we check the values
are properly propagated between stages and they are overwritten as
well.

Components: Vulkan
VK-GL-CTS issue: 2961

Affected tests:

    dEQP-VK.clipping.*.clip_cull_distance*

Signed-off-by: Samuel Iglesias Gonsálvez <siglesias@igalia.com>
Change-Id: I213cc0469e72d82a8eda814e770aac2b825286fc

diff --git a/external/vulkancts/modules/vulkan/clipping/vktClippingTests.cpp b/external/vulkancts/modules/vulkan/clipping/vktClippingTests.cpp
index 56f0c24..bd42982 100644 (file)
--- a/external/vulkancts/modules/vulkan/clipping/vktClippingTests.cpp
+++ b/external/vulkancts/modules/vulkan/clipping/vktClippingTests.cpp
@@ -283,9 +283,29 @@ bool checkFragColors (const tcu::ConstPixelBufferAccess pixels, IVec2 clipRegion
                const int               barWidth                                = pixels.getWidth() / 8;
                const bool              insideBar                               = x >= barWidth * barIdx && x < barWidth * (barIdx + 1);
                const float             expectedClipDistance    = insideBar ? (((((float)y + 0.5f) / (float)pixels.getHeight()) - 0.5f) * 2.0f) : 0.0f;
-               const float             expectedCullDistance    = 0.5f;
+               float                   expectedCullDistance    = 0.5f;
                const float             clipDistance                    = color.y();
                const float             cullDistance                    = color.z();
+               const float             height                                  = (float)pixels.getHeight();
+
+               if (hasCullDistance)
+               {
+                       /* Linear interpolation of the cull distance.
+                        * Remember there are precision errors due to 8-bit UNORM, but they should fall inside 0.01f threshold.
+                        *
+                        * Notes about the results:
+                        * - linear interpolation of gl_CullDistance[i] = [0.0f, 0.5f]. Correct.
+                        * - Constant value:
+                        *   + 0.1f: value written by vertex shader when there are other geometry-related shaders. It means the value was not overriden. Failure.
+                        *   + 0.2f: value written by tessc shader when cull distance value from vertex is not 0.1f. Failure.
+                        *   + 0.3f: value written by tessc shader when cull distance value from vertex is 0.1f and there is geometry shader. Failure.
+                        *   + 0.4f: value written by geometry shader when cull distance is not either 0.1f (if no tess is present) or 0.3f (tess present). Failure.
+                        */
+                       if (y >= (pixels.getHeight() / 2))
+                               expectedCullDistance = expectedCullDistance * (1.0f + (2.0f * (float)y) - height) / height;
+                       else
+                               expectedCullDistance = 0.0f;
+               }
 
                if (fabs(clipDistance - expectedClipDistance) > 0.01f)
                        return false;
@@ -1064,15 +1084,26 @@ void initPrograms (SourceCollections& programCollection, const CaseDefinition ca
                                src << "    for (int i = 0; i < " << caseDef.numClipDistances << "; ++i)\n"
                                        << "        gl_ClipDistance[i] = (barNdx == i ? v_position.y : 0.0);\n";
                        if (caseDef.numCullDistances > 0)
-                               src << "    for (int i = 0; i < " << caseDef.numCullDistances << "; ++i)\n"
-                                       << "        gl_CullDistance[i] = 0.5;\n";
+                       {
+                               src << "    for (int i = 0; i < " << caseDef.numCullDistances << "; ++i)\n";
+                               if (caseDef.enableTessellation || caseDef.enableGeometry)
+                                       src     << "        gl_CullDistance[i] = 0.1f;\n";
+                               else
+                                       src     << "        gl_CullDistance[i] = (gl_Position.y < 0) ? -0.5f : 0.5f;\n";
+                       }
                }
                else
                {
                        for (int i = 0; i < caseDef.numClipDistances; ++i)
                                src << "    gl_ClipDistance[" << i << "] = (barNdx == " << i << " ? v_position.y : 0.0);\n";
+
                        for (int i = 0; i < caseDef.numCullDistances; ++i)
-                               src << "    gl_CullDistance[" << i << "] = 0.5;\n";             // don't cull anything
+                       {
+                               if (caseDef.enableTessellation || caseDef.enableGeometry)
+                                       src     << "    gl_CullDistance[" << i << "] = 0.1f;\n";
+                               else
+                                       src << "    gl_CullDistance[" << i << "] = (gl_Position.y < 0) ? -0.5f : 0.5f;\n";
+                       }
                }
                src     << "}\n";
 
@@ -1112,15 +1143,31 @@ void initPrograms (SourceCollections& programCollection, const CaseDefinition ca
                                src << "    for (int i = 0; i < " << caseDef.numClipDistances << "; ++i)\n"
                                        << "        gl_out[gl_InvocationID].gl_ClipDistance[i] = gl_in[gl_InvocationID].gl_ClipDistance[i];\n";
                        if (caseDef.numCullDistances > 0)
-                               src << "    for (int i = 0; i < " << caseDef.numCullDistances << "; ++i)\n"
-                                       << "        gl_out[gl_InvocationID].gl_CullDistance[i] = gl_in[gl_InvocationID].gl_CullDistance[i];\n";
+                       {
+                               src << "    for (int i = 0; i < " << caseDef.numCullDistances << "; ++i)\n";
+                               src << "    {\n";
+                               src     << "        gl_out[gl_InvocationID].gl_CullDistance[i] = (gl_in[gl_InvocationID].gl_CullDistance[i] == 0.1f) ? ";
+                               if (caseDef.enableGeometry)
+                                       src << "0.3f";
+                               else
+                                       src << "((gl_in[gl_InvocationID].gl_Position.y < 0) ? -0.5f : 0.5f)";
+                               src << " : 0.2f;\n";
+                               src << "    }\n";
+                       }
                }
                else
                {
                        for (int i = 0; i < caseDef.numClipDistances; ++i)
                                src << "    gl_out[gl_InvocationID].gl_ClipDistance[" << i << "] = gl_in[gl_InvocationID].gl_ClipDistance[" << i << "];\n";
                        for (int i = 0; i < caseDef.numCullDistances; ++i)
-                               src << "    gl_out[gl_InvocationID].gl_CullDistance[" << i << "] = gl_in[gl_InvocationID].gl_CullDistance[" << i << "];\n";
+                       {
+                               src     << "    gl_out[gl_InvocationID].gl_CullDistance[" << i << "] = (gl_in[gl_InvocationID].gl_CullDistance[" << i << "] == 0.1f) ? ";
+                               if (caseDef.enableGeometry)
+                                       src << "0.3f";
+                               else
+                                       src << "((gl_in[gl_InvocationID].gl_Position.y < 0) ? -0.5f : 0.5f)";
+                               src << " : 0.2f;\n";
+                       }
                }
                src << "}\n";
 
@@ -1209,15 +1256,32 @@ void initPrograms (SourceCollections& programCollection, const CaseDefinition ca
                                        src << "    for (int i = 0; i < " << caseDef.numClipDistances << "; ++i)\n"
                                                << "        gl_ClipDistance[i] = gl_in[" << vertNdx << "].gl_ClipDistance[i];\n";
                                if (caseDef.numCullDistances > 0)
-                                       src << "    for (int i = 0; i < " << caseDef.numCullDistances << "; ++i)\n"
-                                               << "        gl_CullDistance[i] = gl_in[" << vertNdx << "].gl_CullDistance[i];\n";
+                               {
+                                       src << "    for (int i = 0; i < " << caseDef.numCullDistances << "; ++i)\n";
+                                       src << "    {\n";
+                                       src     << "        gl_CullDistance[i] = (gl_in[" << vertNdx << "].gl_CullDistance[i] == ";
+                                       if (caseDef.enableTessellation)
+                                               src << "0.3f";
+                                       else
+                                               src << "0.1f";
+                                       src << ") ? ((gl_in[" << vertNdx << "].gl_Position.y < 0) ? -0.5f : 0.5f) : 0.4f;\n";
+                                       src << "    }\n";
+                               }
                        }
                        else
                        {
                                for (int i = 0; i < caseDef.numClipDistances; ++i)
                                        src << "    gl_ClipDistance[" << i << "] = gl_in[" << vertNdx << "].gl_ClipDistance[" << i << "];\n";
+
                                for (int i = 0; i < caseDef.numCullDistances; ++i)
-                                       src << "    gl_CullDistance[" << i << "] = gl_in[" << vertNdx << "].gl_CullDistance[" << i << "];\n";
+                               {
+                                       src     << "        gl_CullDistance[" << i << "] = (gl_in[" << vertNdx << "].gl_CullDistance[" << i << "] == ";
+                                       if (caseDef.enableTessellation)
+                                               src << "0.3f";
+                                       else
+                                               src << "0.1f";
+                                       src << ") ? ((gl_in[" << vertNdx << "].gl_Position.y < 0) ? -0.5f : 0.5f) : 0.4f;\n";
+                               }
                        }
                        src << "    EmitVertex();\n";
                }