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/*
* Copyright 2017 Google Inc.
*
* Use of this source code is governed by a BSD-style license that can
* be found in the LICENSE file.
*
*/
//
//
//
#include <math.h>
#include "color.h"
//
// COLOR UTILITIES
//
//
// CONVERT FROM 0xAARRGGBB WORD ORDER INTO f32[4]
//
void
color_rgb32_to_rgba_f32(float rgba[4], const uint32_t rgb, const float opacity)
{
rgba[2] = (float)(rgb & 0xFF) / 255.0f; // b
rgba[1] = (float)(rgb >> 8 & 0xFF) / 255.0f; // g
rgba[0] = (float)(rgb >> 16 & 0xFF) / 255.0f; // r
rgba[3] = opacity;
}
void
color_argb32_to_rgba_f32(float rgba[4], const uint32_t argb)
{
rgba[2] = (float)(argb & 0xFF) / 255.0f; // b
rgba[1] = (float)(argb >> 8 & 0xFF) / 255.0f; // g
rgba[0] = (float)(argb >> 16 & 0xFF) / 255.0f; // r
rgba[3] = (float)(argb >> 24 & 0xFF) / 255.0f; // a
}
//
// { r, g, b, a } ==> { r*a, g*a, b*a, a }
//
void
color_premultiply_rgba_f32(float rgba[4])
{
if (rgba[3] < 1.0f)
{
for (uint32_t ii=0; ii<3; ii++)
rgba[ii] = rgba[ii] * rgba[3];
}
}
//
// EXT_framebuffer_sRGB:
// https://www.opengl.org/registry/specs/EXT/framebuffer_sRGB.txt
//
// { cs / 12.92, cs <= 0.04045
// cl = {
// { ((cs + 0.055)/1.055)^2.4, cs > 0.04045
//
//
// { 0.0, 0 <= cl
// { 12.92 * cl, 0 < cl < 0.0031308
// cs = { 1.055 * cl^0.41666 - 0.055, 0.0031308 <= cl < 1
// { 1.0, cl >= 1
//
void
color_srgb_to_linear_rgb_f32(float rgb[3])
{
for (uint32_t ii=0; ii<3; ii++)
{
if (rgb[ii] <= 0.04045f)
{
rgb[ii] = rgb[ii] / 12.92f;
}
else
{
rgb[ii] = powf((rgb[ii] + 0.055f) / 1.055f, 2.4f);
}
}
}
void
color_linear_to_srgb_rgb_f32(float rgb[3])
{
for (uint32_t ii=0; ii<3; ii++)
{
if (rgb[ii] < 0.0031308f)
{
rgb[ii] = rgb[ii] * 12.92f;
}
else
{
rgb[ii] = powf(rgb[ii], 0.41666f) * 1.044f - 0.055f;
}
}
}
//
//
//
static
float
lerpf(float const a, float const b, float const t)
{
return fmaf(t, b, fmaf(-t, a, a));
}
//
//
//
void
color_linear_lerp_rgba_f32(float rgba_m[4],
float const rgba_a[4],
float const rgba_b[4],
float const t)
{
for (int32_t ii=0; ii<4; ii++)
rgba_m[ii] = lerpf(rgba_a[ii],rgba_b[ii],t);
}
//
//
//
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