[cogl/cogl-1.14: 38/174] Add a simple conformance test for alpha testing

[Robert Bragg <rbragg src gnome org>]

commit 9b59588c53ab3ce5f7af1a05459a8dbbed2984d0
Author: Neil Roberts <neil linux intel com>
Date:   Mon Oct 1 14:46:24 2012 +0100

    Add a simple conformance test for alpha testing
    
    This adds a simple test which sets an alpha test on a pipeline and
    then renders a texture. It then verifies that the transparent parts of
    the texture aren't drawn. This is currently failing with the GL3
    driver because GL3 requires the alpha test to be implemented in GLSL
    but the generated alpha test uniform is only updated for the GLES2
    driver.
    
    Reviewed-by: Robert Bragg <robert linux intel com>
    
    (cherry picked from commit 4ec04507bfaf2d61707dccfb59ac7326962ee741)

 tests/conform/Makefile.am         |    1 +
 tests/conform/test-alpha-test.c   |   74 +++++++++++++++++++++++++++++++++++++
 tests/conform/test-conform-main.c |    2 +
 3 files changed, 77 insertions(+), 0 deletions(-)
---
diff --git a/tests/conform/Makefile.am b/tests/conform/Makefile.am
index 4c9d17e..3e1bfbb 100644
--- a/tests/conform/Makefile.am
+++ b/tests/conform/Makefile.am
@@ -57,6 +57,7 @@ test_sources = \
 	test-gles2-context.c \
 	test-euler-quaternion.c \
 	test-layer-remove.c \
+	test-alpha-test.c \
 	$(NULL)
 
 test_conformance_SOURCES = $(common_sources) $(test_sources)
diff --git a/tests/conform/test-alpha-test.c b/tests/conform/test-alpha-test.c
new file mode 100644
index 0000000..7779ae0
--- /dev/null
+++ b/tests/conform/test-alpha-test.c
@@ -0,0 +1,74 @@
+#include <cogl/cogl.h>
+#include <string.h>
+
+#include "test-utils.h"
+
+static CoglTexture2D *
+create_texture (CoglContext *context)
+{
+  static const uint8_t data[] =
+    {
+      0xff, 0x00, 0x00, 0xff,
+      0x00, 0xfa, 0x00, 0xfa
+    };
+
+  return cogl_texture_2d_new_from_data (context,
+                                        2, 1, /* width/height */
+                                        COGL_PIXEL_FORMAT_RGBA_8888_PRE,
+                                        COGL_PIXEL_FORMAT_ANY,
+                                        4, /* rowstride */
+                                        data,
+                                        NULL /* error */);
+}
+
+void
+test_alpha_test (void)
+{
+  CoglTexture *tex = COGL_TEXTURE (create_texture (ctx));
+  CoglPipeline *pipeline = cogl_pipeline_new (ctx);
+  int fb_width = cogl_framebuffer_get_width (fb);
+  int fb_height = cogl_framebuffer_get_height (fb);
+  CoglColor clear_color;
+
+  cogl_pipeline_set_layer_texture (pipeline, 0, tex);
+  cogl_pipeline_set_layer_filters (pipeline, 0,
+                                   COGL_PIPELINE_FILTER_NEAREST,
+                                   COGL_PIPELINE_FILTER_NEAREST);
+  cogl_pipeline_set_alpha_test_function (pipeline,
+                                         COGL_PIPELINE_ALPHA_FUNC_GEQUAL,
+                                         254 / 255.0f /* alpha reference */);
+
+  cogl_color_init_from_4ub (&clear_color, 0x00, 0x00, 0xff, 0xff);
+  cogl_framebuffer_clear (fb,
+                          COGL_BUFFER_BIT_COLOR,
+                          &clear_color);
+
+  cogl_framebuffer_draw_rectangle (fb,
+                                   pipeline,
+                                   -1, -1,
+                                   1, 1);
+
+  cogl_object_unref (pipeline);
+  cogl_object_unref (tex);
+
+  /* The left side of the framebuffer should use the first pixel from
+   * the texture which is red */
+  test_utils_check_region (fb,
+                           2, 2,
+                           fb_width / 2 - 4,
+                           fb_height - 4,
+                           0xff0000ff);
+  /* The right side of the framebuffer should use the clear color
+   * because the second pixel from the texture is clipped from the
+   * alpha test */
+  test_utils_check_region (fb,
+                           fb_width / 2 + 2,
+                           2,
+                           fb_width / 2 - 4,
+                           fb_height - 4,
+                           0x0000ffff);
+
+  if (cogl_test_verbose ())
+    g_print ("OK\n");
+}
+
diff --git a/tests/conform/test-conform-main.c b/tests/conform/test-conform-main.c
index 7475685..df9d2a5 100644
--- a/tests/conform/test-conform-main.c
+++ b/tests/conform/test-conform-main.c
@@ -100,6 +100,8 @@ main (int argc, char **argv)
 
   ADD_TEST (test_version, 0);
 
+  ADD_TEST (test_alpha_test, 0);
+
   UNPORTED_TEST (test_viewport);
 
   ADD_TEST (test_gles2_context, TEST_REQUIREMENT_GLES2_CONTEXT);