Restrict alpha range for rgba5551 surfaces

The tests were blending against an rgba5551 surface and expecting alpha
to be quantized to 1 bit between every drawcall. The spec does not
forbid implementations to use higher precision internal representations
where this quantisation may not occur to the same extent. This change
restricts fragment outputs to be either 0 or 1, so the issue is avoided

Components: OpenGL

VK-GL-CTS issue: 988

Affects:
dEQP-EGL.functional.render.*rgba5551*

Change-Id: Id8fa5068931124d79ae7fa1b9b8a41845c73e507

diff --git a/modules/egl/teglRenderTests.cpp b/modules/egl/teglRenderTests.cpp
index 46b1780..e6efac5 100644 (file)
--- a/modules/egl/teglRenderTests.cpp
+++ b/modules/egl/teglRenderTests.cpp
@@ -141,7 +141,7 @@ static bool isANarrowScreenSpaceTriangle (const tcu::Vec4& p0, const tcu::Vec4&
        return visibleArea < minimumVisibleArea;
 }
 
-void randomizeDrawOp (de::Random& rnd, DrawPrimitiveOp& drawOp)
+void randomizeDrawOp (de::Random& rnd, DrawPrimitiveOp& drawOp, const bool alphaZeroOrOne)
 {
        const int       minStencilRef   = 0;
        const int       maxStencilRef   = 8;
@@ -173,6 +173,7 @@ void randomizeDrawOp (de::Random& rnd, DrawPrimitiveOp& drawOp)
                {
                        const float             cx              = rnd.getFloat(-1.0f, 1.0f);
                        const float             cy              = rnd.getFloat(-1.0f, 1.0f);
+                       const float             flatAlpha = (rnd.getFloat(minAlpha, maxAlpha) > 0.5f) ? 1.0f : 0.0f;
 
                        for (int coordNdx = 0; coordNdx < 3; coordNdx++)
                        {
@@ -188,6 +189,11 @@ void randomizeDrawOp (de::Random& rnd, DrawPrimitiveOp& drawOp)
                                color.y()               = rnd.getFloat(minRGB, maxRGB);
                                color.z()               = rnd.getFloat(minRGB, maxRGB);
                                color.w()               = rnd.getFloat(minAlpha, maxAlpha);
+
+                               if (alphaZeroOrOne)
+                               {
+                                       color.w()       = flatAlpha;
+                               }
                        }
 
                        // avoid generating narrow triangles
@@ -758,7 +764,7 @@ void SingleThreadRenderCase::executeForContexts (EGLDisplay display, EGLSurface
        // Generate draw ops.
        drawOps.resize(numContexts*drawsPerCtx*numIters);
        for (vector<DrawPrimitiveOp>::iterator drawOp = drawOps.begin(); drawOp != drawOps.end(); ++drawOp)
-               randomizeDrawOp(rnd, *drawOp);
+               randomizeDrawOp(rnd, *drawOp, (pixelFmt.alphaBits == 1));
 
        // Create and setup programs per context
        for (int ctxNdx = 0; ctxNdx < numContexts; ctxNdx++)
@@ -970,7 +976,7 @@ void MultiThreadRenderCase::executeForContexts (EGLDisplay display, EGLSurface s
 
        // Create draw ops.
        for (vector<DrawPrimitiveOp>::iterator drawOp = drawOps.begin(); drawOp != drawOps.end(); ++drawOp)
-               randomizeDrawOp(rnd, *drawOp);
+               randomizeDrawOp(rnd, *drawOp, (pixelFmt.alphaBits == 1));
 
        // Create packets.
        for (int threadNdx = 0; threadNdx < numThreads; threadNdx++)