[Piglit] [PATCH] fbo-depth-array: Don't create an enormous color render target

[Neil Roberts]

When the -fbo option is given to the fbo-depth-array test it tries to
render to a range of different depth/stencil buffer sizes with
dimensions of up to 8192. It verifies the rendering was correct by
binding the depth or stencil buffer as a texture source, rendering the
texture into the Piglit winsys fbo and then probing the result. In
order to cope with all of the possible buffer sizes it was setting the
winsys framebuffer size to 8192x8192. Doing glReadPixels on a buffer
this size causes problems for some platforms and makes the test run
extremely slowly. The point of the test is just to check rendering to
depth and stencil array textures of different sizes so the size of the
renderbuffer isn't really relevant. This patch makes it instead leave
the winsys buffer at the default size when an FBO is used and then
render the texture multiple times in slices until it has checked the
entire texture.
---
 tests/fbo/fbo-depth-array.c | 53 ++++++++++++++++++++++++++++++---------------
 1 file changed, 35 insertions(+), 18 deletions(-)

diff --git a/tests/fbo/fbo-depth-array.c b/tests/fbo/fbo-depth-array.c
index 1ea6611..b0acd5e 100644
--- a/tests/fbo/fbo-depth-array.c
+++ b/tests/fbo/fbo-depth-array.c
@@ -65,11 +65,7 @@ PIGLIT_GL_TEST_CONFIG_BEGIN
 	config.supports_gl_compat_version = 33;
 	config.supports_gl_core_version = 33;
 
-	if (piglit_use_fbo && !test_single_size) {
-		config.window_width = MAX_DIM;
-		config.window_height = MAX_DIM;
-	}
-	else {
+	if (!piglit_use_fbo || test_single_size) {
 		config.window_width = (width + 2) * MIN2(layers, 4);
 		config.window_height = (height + 2) * ((layers + 2) / 3);
 	}
@@ -359,7 +355,10 @@ done:
  * array texture.
  */
 static void
-draw_layer(int x, int y, int depth)
+draw_layer(int x, int y,
+	   int tx, int ty,
+	   int tw, int th,
+	   int depth)
 {
 	GLfloat depth_coord = (GLfloat)depth;
 	GLuint prog = test_stencil ? program_texstencil : program_texdepth;
@@ -385,18 +384,41 @@ draw_layer(int x, int y, int depth)
 
 	piglit_draw_rect_tex((double)x / piglit_width * 2 - 1,
 			     (double)y / piglit_height * 2 - 1,
-			     (double)width / piglit_width * 2,
-			     (double)height / piglit_height * 2,
-			     0, 0, 1, 1);
+			     (double)tw / piglit_width * 2,
+			     (double)th / piglit_height * 2,
+			     tx / (float) width, ty / (float) height,
+			     tw / (float) width, th / (float) height);
 	glUseProgram(0);
 	if (!piglit_check_gl_error(GL_NO_ERROR))
 		piglit_report_result(PIGLIT_FAIL);
 }
 
-static GLboolean test_layer_drawing(int start_x, int start_y, float expected)
+static GLboolean draw_and_test_layer(int start_x, int start_y,
+				     int layer)
 {
-	return piglit_probe_rect_r_ubyte(start_x, start_y, width, height,
-					 expected * 255.0);
+	float expected = (test_stencil ?
+			  get_stencil_value_float(layer) :
+			  get_depth_value(layer));
+	int tx, ty, tw, th;
+	GLboolean pass = GL_TRUE;
+
+	for (ty = 0; ty < height; ty += piglit_height - start_y) {
+		for (tx = 0; tx < width; tx += piglit_width - start_x) {
+			tw = MIN2(piglit_width - start_x, width - tx);
+			th = MIN2(piglit_height - start_y, height - ty);
+			draw_layer(start_x, start_y,
+				   tx, ty,
+				   tw, th,
+				   layer);
+
+			pass = piglit_probe_rect_r_ubyte(start_x, start_y,
+							 tw, th,
+							 expected * 255.0) &&
+				pass;
+		}
+	}
+
+	return pass;
 }
 
 static bool
@@ -424,12 +446,7 @@ test_once(void)
 			x = 1 + (layer % 3) * (width + 1);
 			y = 1 + (layer / 3) * (height + 1);
 		}
-		draw_layer(x, y, layer);
-
-		pass &= test_layer_drawing(x, y,
-					   test_stencil ?
-					   get_stencil_value_float(layer) :
-					   get_depth_value(layer));
+		draw_and_test_layer(x, y, layer);
 
 		if (piglit_use_fbo && !test_single_size && layer < layers-1) {
 			glClearColor(0.2, 0.1, 0.1, 1.0);
-- 
1.9.3