[Piglit] [PATCH] Add glsl-1.30/execution/fs-fwidth-color.shader_test

[Nicolai Hähnle]

Based on the test in https://bugs.freedesktop.org/show_bug.cgi?id=95130
which exposed an error in radeonsi non-monolithic fragment shaders.
---
 .../execution/fs-fwidth-color.shader_test          | 44 ++++++++++++++++++++++
 1 file changed, 44 insertions(+)
 create mode 100644 tests/spec/glsl-1.30/execution/fs-fwidth-color.shader_test

diff --git a/tests/spec/glsl-1.30/execution/fs-fwidth-color.shader_test b/tests/spec/glsl-1.30/execution/fs-fwidth-color.shader_test
new file mode 100644
index 0000000..c5d050b
--- /dev/null
+++ b/tests/spec/glsl-1.30/execution/fs-fwidth-color.shader_test
@@ -0,0 +1,44 @@
+# Tests that fwidth (as a stand-in for derivatives more generally) works
+# correctly with gl_Color along boundary pixels.
+#
+# A rotated triangle is drawn with a constant color, with the fragment
+# shader returning fwidth(color) -- that is, all drawn pixels should be
+# black.
+#
+# See https://bugs.freedesktop.org/show_bug.cgi?id=95130
+#
+[require]
+GLSL >= 1.30
+GL_ARB_explicit_attrib_location
+
+[vertex shader]
+#version 130
+
+in vec4 piglit_vertex;
+
+void main()
+{
+	float pi = 3.141592653589793;
+	float rotation = 0.13;
+	float angle = float(gl_VertexID) * (2 * pi / 3) + rotation;
+	gl_Position = vec4(sin(angle), -cos(angle), 0.5, 1.0);
+	gl_FrontColor = vec4(0.5);
+}
+
+[fragment shader]
+#version 130
+#extension GL_ARB_explicit_attrib_location : enable
+
+layout(location = 0) out vec4 outcolor;
+in vec4 attrib;
+
+void main()
+{
+	outcolor = fwidth(gl_Color);
+}
+
+[test]
+clear color 0.0 0.0 0.0 0.0
+clear
+draw arrays GL_TRIANGLES 0 3
+probe all rgba 0 0 0 0
-- 
2.7.4