[Piglit] [PATCH 1/2] Add utility functions to convert a color value to srgb or linear color space

[Anuj Phogat]

Signed-off-by: Anuj Phogat <anuj.phogat at gmail.com>
---
 tests/util/piglit-util-gl-common.h |  2 ++
 tests/util/piglit-util-gl.c        | 28 ++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+)

diff --git a/tests/util/piglit-util-gl-common.h b/tests/util/piglit-util-gl-common.h
index e2df89d..0078041 100644
--- a/tests/util/piglit-util-gl-common.h
+++ b/tests/util/piglit-util-gl-common.h
@@ -208,6 +208,8 @@ piglit_visualize_image(float *img, GLenum base_internal_format,
 		       int image_width, int image_height,
 		       int image_count, bool rhs);
 
+float piglit_srgb_to_linear(float x);
+float piglit_linear_to_srgb(float x);
 
 extern GLfloat cube_face_texcoords[6][4][3];
 extern const char *cube_face_names[6];
diff --git a/tests/util/piglit-util-gl.c b/tests/util/piglit-util-gl.c
index 7805498..3dbeec8 100644
--- a/tests/util/piglit-util-gl.c
+++ b/tests/util/piglit-util-gl.c
@@ -1507,3 +1507,31 @@ piglit_visualize_image(float *img, GLenum base_internal_format,
 		     visualization);
 	free(visualization);
 }
+
+/**
+ * Convert from sRGB color space to linear color space, using the
+ * formula from the GL 3.0 spec, section 4.1.8 (sRGB Texture Color
+ * Conversion).
+ */
+float
+piglit_srgb_to_linear(float x)
+{
+        if (x <= 0.0405)
+                return x / 12.92;
+        else
+                return pow((x + 0.055) / 1.055, 2.4);
+}
+
+/* Convert from linear color space to sRGB color space. */
+float
+piglit_linear_to_srgb(float x)
+{
+   if (x < 0.0f)
+      return 0.0f;
+   else if (x < 0.0031308f)
+      return 12.92f * x;
+   else if (x < 1.0f)
+      return 1.055f * powf(x, 0.41666f) - 0.055f;
+   else
+      return 1.0f;
+}
-- 
1.8.1.4