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@Akira-Hayasaka
Last active June 2, 2022 07:55
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hdr.frag
#version 150
uniform sampler2DRect tex;
uniform float r_for_hlg;
in vec2 texCoordVarying;
out vec4 outputColor;
// HLG OETF
vec3 hlg_oetf(vec3 E)
{
const float a = 0.17883277;
const float b = 1.0 - 4.0 * a;
const float c = 0.5 - a * log(4.0 * a);
const float r = 0.5;
const float one_over_12 = 1.0 / 12.0;
float r_prime = 0.0;
float g_prime = 0.0;
float b_prime = 0.0;
if (0.0 <= E.r && E.r <= one_over_12)
r_prime = sqrt(3.0 * E.r);
else if (one_over_12 < E.r && E.r <= 1.0)
r_prime = a * log(12.0 * E.r - b) + c;
if (0.0 <= E.g && E.g <= one_over_12)
g_prime = sqrt(3.0 * E.g);
else if (one_over_12 < E.g && E.g <= 1.0)
g_prime = a * log(12.0 * E.g - b) + c;
if (0.0 <= E.b && E.b <= one_over_12)
b_prime = sqrt(3.0 * E.b);
else if (one_over_12 < E.b && E.b <= 1.0)
b_prime = a * log(12.0 * E.b - b) + c;
return vec3(r_prime, g_prime, b_prime);
}
// HLG inverse OOTF
vec3 hlg_iootf(vec3 rgb_d)
{
const float gamma = 1.2734;
const float alpha = 1500.0;
float y_d = 0.2627 * rgb_d.r + 0.678 * rgb_d.g + 0.0593 * rgb_d.b;
float tmp = pow(y_d / alpha, (1.0 - gamma) / gamma);
float r_s = tmp * (rgb_d.r / alpha);
float g_s = tmp * (rgb_d.g / alpha);
float b_s = tmp * (rgb_d.b / alpha);
return vec3(r_s, g_s, b_s);
}
// HLG inverse EOTF
vec3 hlg_ieotf(vec3 rgb)
{
return hlg_oetf(hlg_iootf(rgb));
}
void main()
{
vec2 tc = texCoordVarying.st;
vec4 sdr_0_1 = texture(tex, tc); // 0.0 - 1.0
// conv hlg
vec3 hlg_col = hlg_ieotf(sdr_0_1.rgb);
outputColor = vec4(hlg_col, sdr_0_1.a);
}
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