#version 450

#extension GL_EXT_shader_8bit_storage                      : require
#extension GL_EXT_shader_explicit_arithmetic_types_int8    : require
#extension GL_EXT_scalar_block_layout                      : require

//#define GL_EXT_shader_8bit_storage                               1

struct ComputeParameters {
    uint8_t tintMapType;
};

layout (binding = 0) uniform ParameterUBO {
    ComputeParameters params;
} ubo;


layout(std430, binding = 1) readonly buffer TexelSSBOIn {
   u8vec4 texelsIn[];
};

layout(std430, binding = 2) buffer TexelSSBOOut {
   u8vec4 texelsOut[];
};

layout(scalar, binding = 3) readonly buffer ComputeSSBOIn {
   u8vec3 tintMapIn[];
};

layout (local_size_x = 256, local_size_y = 1, local_size_z = 1) in;



void main()
{
    uint idx = gl_GlobalInvocationID.x;

    u8vec4 texelIn = texelsIn[idx];

    // Grayscale code
//    float gray = dot(vec3(texelIn.rgb), vec3(0.2627, 0.6780, 0.0593));
//    texelsOut[idx] = u8vec4(u8vec3(gray), 1.0);

    // TintMap code
    uint8_t gray = uint8_t(dot(vec3(texelIn.rgb), vec3(0.2627, 0.6780, 0.0593)));
   texelsOut[idx] = u8vec4(tintMapIn[ubo.params.tintMapType * 256 + gray], 1.0);
//    texelsOut[idx] = u8vec4(tintMapIn[191], 1.0);
}