1 files changed, 38 insertions, 0 deletions
diff --git a/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_bright_contrast.glsl b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_bright_contrast.glsl
new file mode 100644
index 00000000000..ce71b4fd8a4
--- /dev/null
+++ b/source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_bright_contrast.glsl
@@ -0,0 +1,38 @@
+#pragma BLENDER_REQUIRE(gpu_shader_common_color_utils.glsl)
+
+/* The algorithm is by Werner D. Streidt
+ * (http://visca.com/ffactory/archives/5-99/msg00021.html)
+ * Extracted of OpenCV demhist.c
+ */
+
+#define FLT_EPSILON 1.192092896e-07F
+
+void node_composite_bright_contrast(
+    vec4 color, float brightness, float contrast, const float use_premultiply, out vec4 result)
+{
+  brightness /= 100.0;
+  float delta = contrast / 200.0;
+
+  float multiplier, offset;
+  if (contrast > 0.0) {
+    multiplier = 1.0 - delta * 2.0;
+    multiplier = 1.0 / max(multiplier, FLT_EPSILON);
+    offset = multiplier * (brightness - delta);
+  }
+  else {
+    delta *= -1.0;
+    multiplier = max(1.0 - delta * 2.0, 0.0);
+    offset = multiplier * brightness + delta;
+  }
+
+  if (use_premultiply != 0.0) {
+    color_alpha_unpremultiply(color, color);
+  }
+
+  result.rgb = color.rgb * multiplier + offset;
+  result.a = color.a;
+
+  if (use_premultiply != 0.0) {
+    color_alpha_premultiply(result, result);
+  }
+}