[Piglit] [PATCH] Add a test for viewport triangle clipping.

[Stuart Abercrombie]

Triangles should be clipped to the clip volume and therefore shouldn't end up being rasterized outside the viewport.

This was failing on Sandy Bridge with guard band clipping enabled.

v2 with a new name, more comments and addition to all.tests.
---
 tests/all.tests                             |    1 +
 tests/general/CMakeLists.gl.txt             |    1 +
 tests/general/triangle-guardband-viewport.c |   62 +++++++++++++++++++++++++++
 3 files changed, 64 insertions(+), 0 deletions(-)
 create mode 100644 tests/general/triangle-guardband-viewport.c

diff --git a/tests/all.tests b/tests/all.tests
index 0a8a5aa..954a96c 100644
--- a/tests/all.tests
+++ b/tests/all.tests
@@ -556,6 +556,7 @@ add_plain_test(gl11, 'streaming-texture-leak')
 add_plain_test(gl11, 'texredefine')
 add_plain_test(gl11, 'texsubimage')
 add_plain_test(gl11, 'texture-al')
+add_plain_test(gl11, 'triangle-guardband-viewport')
 
 gl10 = Group()
 spec['!OpenGL 1.0'] = gl10
diff --git a/tests/general/CMakeLists.gl.txt b/tests/general/CMakeLists.gl.txt
index 11da25f..a26371c 100644
--- a/tests/general/CMakeLists.gl.txt
+++ b/tests/general/CMakeLists.gl.txt
@@ -134,5 +134,6 @@ piglit_add_executable (occlusion-query-discard occlusion-query-discard.c)
 piglit_add_executable (quad-invariance quad-invariance.c)
 piglit_add_executable (clear-accum clear-accum.c)
 piglit_add_executable (vs-point_size-zero vs-point_size-zero.c)
+piglit_add_executable (triangle-guardband-viewport triangle-guardband-viewport.c)
 
 # vim: ft=cmake:
diff --git a/tests/general/triangle-guardband-viewport.c b/tests/general/triangle-guardband-viewport.c
new file mode 100644
index 0000000..fcd11fe
--- /dev/null
+++ b/tests/general/triangle-guardband-viewport.c
@@ -0,0 +1,62 @@
+/** @file triangle-guardband-vewport.c
+ *
+ * Tests whether clipping of triangles to the clip volume
+ * is reflected in what is rasterized. Specifically,
+ * triangles (unlike some other primitives) should not be
+ * rasterized outside the viewport extents because they should
+ * have been clipped to the clip volume mapping to the viewport.
+ *
+ * Faulty guard-band clipping optimizations have been known to
+ * not honor this requirement.
+ */
+
+#include "piglit-util-gl-common.h"
+
+PIGLIT_GL_TEST_CONFIG_BEGIN
+
+	config.supports_gl_compat_version = 10;
+
+	config.window_width = 100;
+	config.window_height = 100;
+	config.window_visual = PIGLIT_GL_VISUAL_DOUBLE | PIGLIT_GL_VISUAL_RGB;
+
+PIGLIT_GL_TEST_CONFIG_END
+
+enum piglit_result
+piglit_display(void)
+{
+	GLboolean pass = GL_TRUE;
+	static float green[] = {0.0, 1.0, 0.0, 0.0};
+	static float blue[]  = {0.0, 0.0, 1.0, 0.0};
+
+	/* make the whole window green. */
+	glClearColor(0.0, 1.0, 0.0, 0.0);
+	glClear(GL_COLOR_BUFFER_BIT);
+
+	/* set viewport to the left half of the window */
+	glViewport(0, 0, piglit_width / 2, piglit_height);
+
+	/* draw blue rect extending beyond the right edge of the
+	   frustrum, notionally across the whole window */
+	glColor4fv(blue);
+	piglit_draw_rect(-1.0, -1.0, 4.0, 2.0);
+
+	/* check that the right half of the window, outside
+	   the viewport, still has the clear color */
+	pass &= piglit_probe_rect_rgb(piglit_width/2, 0,
+				piglit_width/2, piglit_height, green);
+
+	piglit_present_results();
+
+	return pass ? PIGLIT_PASS : PIGLIT_FAIL;
+}
+
+void
+piglit_init(int argc, char **argv)
+{
+	glMatrixMode(GL_PROJECTION);
+	glLoadIdentity();
+
+	glMatrixMode(GL_MODELVIEW);
+	glLoadIdentity();
+}
-- 
1.7.7.3