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#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);
}
}
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