[Piglit] [PATCH 07/16] msaa/formats: Use a scale and offset for testing integer formats.

[Paul Berry]

This patch adapts the MSAA "formats" test so that when drawing into
integer framebuffers, it applies the necessary scale and offset to
cover the entire range of possible integer values.  When reading
pixels back from the framebuffer, the test applies the inverse scale
and offset, so that the result can be compared to the reference RGBA
image.
---
 tests/spec/ext_framebuffer_multisample/formats.cpp |   22 +++++++++++++++++++-
 1 files changed, 21 insertions(+), 1 deletions(-)

diff --git a/tests/spec/ext_framebuffer_multisample/formats.cpp b/tests/spec/ext_framebuffer_multisample/formats.cpp
index b54cda7..d2386ad 100644
--- a/tests/spec/ext_framebuffer_multisample/formats.cpp
+++ b/tests/spec/ext_framebuffer_multisample/formats.cpp
@@ -88,6 +88,17 @@ public:
 	 */
 	ColorGradientSunburst *test_pattern;
 
+	/**
+	 * Color offset that will be used to draw the test pattern.
+	 */
+	float color_offset;
+
+	/**
+	 * Color scale factor that will be used to draw the test
+	 * pattern.
+	 */
+	float color_scale;
+
 	Fbo fbo_msaa;
 	Fbo fbo_downsampled;
 };
@@ -132,13 +143,19 @@ PatternRenderer::try_setup(GLenum internalformat)
 	switch (component_type) {
 	case GL_INT:
 		test_pattern = test_pattern_ivec4;
+		color_offset = 1.0 - pow(2.0, color_bits[0] - 1);
+		color_scale = -2.0 * color_offset;
 		break;
 	case GL_UNSIGNED_INT:
 		test_pattern = test_pattern_uvec4;
+		color_scale = pow(2.0, color_bits[0]) - 1.0;
+		color_offset = 0.0;
 		break;
 	case GL_UNSIGNED_NORMALIZED:
 	case GL_FLOAT:
 		test_pattern = test_pattern_vec4;
+		color_offset = 0.0;
+		color_scale = 1.0;
 		break;
 	default:
 		printf("Unrecognized component type: %s\n",
@@ -191,7 +208,8 @@ PatternRenderer::draw()
 	/* Draw into the MSAA fbo */
 	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, fbo_msaa.handle);
 	fbo_msaa.set_viewport();
-	test_pattern->draw(TestPattern::no_projection);
+	test_pattern->draw_with_scale_and_offset(TestPattern::no_projection,
+						 color_scale, color_offset);
 
 	/* Blit to the downsampled fbo, forcing the image to be downsampled */
 	glBindFramebuffer(GL_READ_FRAMEBUFFER, fbo_msaa.handle);
@@ -267,6 +285,8 @@ PatternRenderer::read_image(GLenum base_format)
 		glReadPixels(0, 0, pattern_width, pattern_height, base_format,
 			     GL_FLOAT, image);
 	}
+	for (unsigned i = 0; i < array_size; ++i)
+		image[i] = (image[i] - color_offset) / color_scale;
 	return image;
 }
 
-- 
1.7.7.6