CTests: Initial work to cover Cycles nodes with OpenGL tests

Works similar to regular Cycles tests, just does OpenGL render to
get output image.

Seems to work fine with the only funny effect: Blender window will
pop up for each of the tests. This is current limitation of our
OpenGL context. Might be changed in the future.

tests/python/CMakeLists.txt

@@ -418,6 +418,9 @@ if(WITH_CYCLES)
 				)
 			endif()
 		endmacro()
+		if(WITH_OPENGL_TESTS)
+			add_cycles_render_test(opengl)
+		endif()
 		add_cycles_render_test(reports)
 		add_cycles_render_test(render)
 		add_cycles_render_test(shader)

tests/python/cycles_render_tests.py

@@ -47,20 +47,41 @@ def printMessage(type, status, message):
 
 
 def render_file(filepath):
-    command = (
-        BLENDER,
-        "--background",
-        "-noaudio",
-        "--factory-startup",
-        "--enable-autoexec",
-        filepath,
-        "-E", "CYCLES",
-        # Run with OSL enabled
-        # "--python-expr", "import bpy; bpy.context.scene.cycles.shading_system = True",
-        "-o", TEMP_FILE_MASK,
-        "-F", "PNG",
-        "-f", "1",
+    dirname = os.path.dirname(filepath)
+    basedir = os.path.dirname(dirname)
+    subject = os.path.basename(dirname)
+    if subject == 'opengl':
+        command = (
+            BLENDER,
+            "--window-geometry", "0", "0", "1", "1",
+            "-noaudio",
+            "--factory-startup",
+            "--enable-autoexec",
+            filepath,
+            "-E", "CYCLES",
+            # Run with OSL enabled
+            # "--python-expr", "import bpy; bpy.context.scene.cycles.shading_system = True",
+            "-o", TEMP_FILE_MASK,
+            "-F", "PNG",
+            '--python', os.path.join(basedir,
+                                     "util",
+                                     "render_opengl.py")
         )
+    else:
+        command = (
+            BLENDER,
+            "--background",
+            "-noaudio",
+            "--factory-startup",
+            "--enable-autoexec",
+            filepath,
+            "-E", "CYCLES",
+            # Run with OSL enabled
+            # "--python-expr", "import bpy; bpy.context.scene.cycles.shading_system = True",
+            "-o", TEMP_FILE_MASK,
+            "-F", "PNG",
+            "-f", "1",
+            )
     try:
         output = subprocess.check_output(command)
         if VERBOSE: