diff options
Diffstat (limited to 'source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_bright_contrast.glsl')
-rw-r--r-- | source/blender/gpu/shaders/compositor/library/gpu_shader_compositor_bright_contrast.glsl | 38 |
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); + } +} |