From 9b59588c53ab3ce5f7af1a05459a8dbbed2984d0 Mon Sep 17 00:00:00 2001
From: Neil Roberts <neil@linux.intel.com>
Date: Mon, 1 Oct 2012 14:46:24 +0100
Subject: [PATCH] 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(+)
 create mode 100644 tests/conform/test-alpha-test.c

diff --git a/tests/conform/Makefile.am b/tests/conform/Makefile.am
index 4c9d17e33..3e1bfbb97 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 000000000..7779ae0df
--- /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 747568503..df9d2a5ad 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);