// mcpro24fps HLG 87% to 2.4 gamma
// ver. 2020-04-13

__CONSTANT__ float A = 0.17883277;
__CONSTANT__ float B = 0.28466892;
__CONSTANT__ float C = 0.55991073;
__CONSTANT__ float BLACK = 0.02;
__CONSTANT__ float WHITE = 0.87;

__DEVICE__ float3 transform(int p_Width, int p_Height, int p_X, int p_Y, float p_R, float p_G, float p_B)
{
	float3 rgb;
 
	rgb.x = p_R;
    rgb.y = p_G;
    rgb.z = p_B;

	//HLG 95
	if(rgb.x < BLACK)
		rgb.x = 0.0;
	else {
		rgb.x = (rgb.x - BLACK)/(WHITE - BLACK);
		rgb.x = rgb.x < 0.5 ? _powf(rgb.x,2.0)/3.0 : (_expf((rgb.x-C)/A) + B)/12.0;
	}
	if(rgb.y < BLACK)
		rgb.y = 0.0;
	else {
		rgb.y = (rgb.y - BLACK)/(WHITE - BLACK);
		rgb.y = rgb.y < 0.5 ? _powf(rgb.y,2.0)/3.0 : (_expf((rgb.y-C)/A) + B)/12.0;
	}
	if(rgb.z < BLACK)
		rgb.z = 0.0;
	else {
		rgb.z = (rgb.z - BLACK)/(WHITE - BLACK);
		rgb.z = rgb.z < 0.5 ? _powf(rgb.z,2.0)/3.0 : (_expf((rgb.z-C)/A) + B)/12.0;
	}
	
	//Gamma 2.4
	rgb.x = rgb.x < 0 ? 0 : _powf(rgb.x, 1.0f/2.4f);
    rgb.y = rgb.y < 0 ? 0 : _powf(rgb.y, 1.0f/2.4f);
    rgb.z = rgb.z < 0 ? 0 : _powf(rgb.z, 1.0f/2.4f);

    return rgb;
}