[Piglit] [PATCH] msaa: Verify proper operation of alpha blending.

[Paul Berry]

A bug has been discovered in Mesa's implementation of MSAA for
i965/Gen7 when alpha blending is in use.  This test is a minor
revision of the test case from the bug report.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=53077
---
 tests/all.tests                                    |    1 +
 .../ext_framebuffer_multisample/CMakeLists.gl.txt  |    1 +
 .../ext_framebuffer_multisample/alpha-blending.c   |  105 ++++++++++++++++++++
 3 files changed, 107 insertions(+), 0 deletions(-)
 create mode 100644 tests/spec/ext_framebuffer_multisample/alpha-blending.c

diff --git a/tests/all.tests b/tests/all.tests
index e317d15..9419e73 100644
--- a/tests/all.tests
+++ b/tests/all.tests
@@ -1381,6 +1381,7 @@ ext_framebuffer_multisample['negative-readpixels'] = concurrent_test('ext_frameb
 ext_framebuffer_multisample['renderbufferstorage-samples'] = concurrent_test('ext_framebuffer_multisample-renderbufferstorage-samples')
 ext_framebuffer_multisample['renderbuffer-samples'] = concurrent_test('ext_framebuffer_multisample-renderbuffer-samples')
 ext_framebuffer_multisample['samples'] = concurrent_test('ext_framebuffer_multisample-samples')
+ext_framebuffer_multisample['alpha-blending'] = PlainExecTest('ext_framebuffer_multisample-alpha-blending -auto')
 
 for num_samples in MSAA_SAMPLE_COUNTS:
         for test_type in ('color', 'srgb', 'stencil_draw', 'stencil_resolve',
diff --git a/tests/spec/ext_framebuffer_multisample/CMakeLists.gl.txt b/tests/spec/ext_framebuffer_multisample/CMakeLists.gl.txt
index ec5d05f..e486613 100644
--- a/tests/spec/ext_framebuffer_multisample/CMakeLists.gl.txt
+++ b/tests/spec/ext_framebuffer_multisample/CMakeLists.gl.txt
@@ -10,6 +10,7 @@ link_libraries (
 )
 
 piglit_add_executable (ext_framebuffer_multisample-accuracy common.cpp accuracy.cpp)
+piglit_add_executable (ext_framebuffer_multisample-alpha-blending alpha-blending.c)
 piglit_add_executable (ext_framebuffer_multisample-alpha-to-one-msaa-disabled common.cpp
 		       draw-buffers-common.cpp alpha-to-one-msaa-disabled.cpp)
 piglit_add_executable (ext_framebuffer_multisample-alpha-to-one-single-sample-buffer common.cpp
diff --git a/tests/spec/ext_framebuffer_multisample/alpha-blending.c b/tests/spec/ext_framebuffer_multisample/alpha-blending.c
new file mode 100644
index 0000000..013def3
--- /dev/null
+++ b/tests/spec/ext_framebuffer_multisample/alpha-blending.c
@@ -0,0 +1,105 @@
+/*
+ * Copyright © 2012 Intel Corporation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+/** \file alpha-blending.c
+ *
+ * This test checks for Mesa bug 53077 (Output error with msaa when
+ * both of framebuffer and source color's alpha are not 1).  The test
+ * operates by drawing a partially transparent non-square rectangle to
+ * a multisampled buffer (using a triangle fan) and then blitting the
+ * result to the screen.  If the bug is present, artifacts will appear
+ * along the rectangle diagonal due to alpha blending being performed
+ * incorrectly while drawing the first triangle of the fan.
+ *
+ * See also https://bugs.freedesktop.org/show_bug.cgi?id=53077
+ */
+
+#include "piglit-util-gl-common.h"
+
+GLuint framebuffer, renderbuffer;
+#define WIDTH 300
+#define HEIGHT 350
+int numSamples;
+
+PIGLIT_GL_TEST_MAIN(
+    WIDTH,
+    HEIGHT,
+    GLUT_DOUBLE| GLUT_RGBA | GLUT_ALPHA);
+
+void
+piglit_init(int argc, char **argv)
+{
+	glGetIntegerv(GL_MAX_SAMPLES_EXT, &numSamples);
+
+	glGenFramebuffersEXT(1, &framebuffer);
+	glGenRenderbuffersEXT(1, &renderbuffer);
+	glBindFramebufferEXT(GL_FRAMEBUFFER, framebuffer);
+	glBindRenderbufferEXT(GL_RENDERBUFFER, renderbuffer);
+	glRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER, numSamples, GL_RGBA, WIDTH, HEIGHT);
+	glFramebufferRenderbufferEXT(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, renderbuffer);
+	glEnable (GL_MULTISAMPLE);
+}
+
+enum piglit_result
+piglit_display()
+{
+	GLenum src_factor, dst_factor;
+	float expected_color[] = { 0.0, 0.7, 0.0, 0.79 };
+	int x0 = 140;
+	int x1 = 220;
+	int y0 = 55;
+	int y1 = 165;
+	bool pass = true;
+	float vertex_data[][2] = {
+		{ ((float) x0)/WIDTH * 2.0 - 1.0, ((float) y0)/HEIGHT * 2.0 - 1.0 },
+		{ ((float) x1)/WIDTH * 2.0 - 1.0, ((float) y0)/HEIGHT * 2.0 - 1.0 },
+		{ ((float) x1)/WIDTH * 2.0 - 1.0, ((float) y1)/HEIGHT * 2.0 - 1.0 },
+		{ ((float) x0)/WIDTH * 2.0 - 1.0, ((float) y1)/HEIGHT * 2.0 - 1.0 },
+	};
+
+	glBindFramebufferEXT(GL_FRAMEBUFFER,framebuffer);
+
+	glClearColor(0.0, 0.0, 0.0, 1.0);
+	glClear(GL_COLOR_BUFFER_BIT);
+
+	glEnable(GL_BLEND);
+	src_factor = GL_SRC_ALPHA;
+	dst_factor = GL_ONE_MINUS_SRC_ALPHA;
+	glBlendFunc (src_factor, dst_factor);
+	glColor4f (0.0, 1.0, 0.0, 0.7);
+	glVertexPointer(2, GL_FLOAT, 0, vertex_data);
+	glEnableClientState(GL_VERTEX_ARRAY);
+	glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+
+	glBindFramebufferEXT(GL_READ_FRAMEBUFFER, framebuffer);
+	glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER, 0);
+	glBlitFramebuffer(0, 0, WIDTH, HEIGHT, 0, 0, WIDTH, HEIGHT, GL_COLOR_BUFFER_BIT, GL_NEAREST);
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+	pass = piglit_probe_rect_rgba(x0, y0, x1 - x0, y1 - y0, expected_color)
+		&& pass;
+
+	piglit_present_results();
+
+	return pass ? PIGLIT_PASS : PIGLIT_FAIL;
+}
-- 
1.7.7.6