GammaCorrection.cpp

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#include <glad/glad.h>
 
#include "galaxy/core/Config.hpp"
#include "galaxy/core/ServiceLocator.hpp"
 
#include "GammaCorrection.hpp"
 
constexpr const char* const gammacorrection_vert = R"(
    #version 460 core
    layout (location = 0) in vec2 l_pos;
    layout (location = 1) in vec2 l_texels;
 
    void main()
    {
        gl_Position = vec4(l_pos, 0.0, 1.0);
    }
)";
 
constexpr const char* const gammacorrection_frag = R"(
    #version 460 core
 
    out vec4 io_frag_colour;
 
    uniform float u_gamma;
    uniform sampler2D u_texture;
 
    void main()
    {
        vec2 uv = gl_FragCoord.xy / textureSize(u_texture, 0).xy;
 
        io_frag_colour = texture(u_texture, uv);
        io_frag_colour.rgb = pow(io_frag_colour.rgb, vec3(1.0 / u_gamma));
    }
)";
 
namespace galaxy
{
    namespace graphics
    {
        GammaCorrection::GammaCorrection(const int width, const int height)
            : m_gamma {2.2f}
        {
            m_fb.create(width, height);
 
            if (m_shader.parse(gammacorrection_vert, gammacorrection_frag))
            {
                m_shader.compile();
                m_shader.set_uniform("u_texture", 0);
                m_shader.set_uniform("u_gamma", m_gamma);
            }
        }
 
        void GammaCorrection::resize(const int width, const int height)
        {
            m_fb.recreate(width, height);
        }
 
        unsigned int GammaCorrection::render(const unsigned int input)
        {
            m_fb.bind(true);
            m_shader.bind();
 
            glActiveTexture(GL_TEXTURE0);
            glBindTexture(GL_TEXTURE_2D, input);
            glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
 
            return m_fb.texture();
        }
 
        void GammaCorrection::set_gamma(const float gamma_mod)
        {
            m_gamma = gamma_mod;
 
            if (static_cast<int>(m_gamma) == 0)
            {
                m_gamma = 1.0f;
            }
 
            m_shader.set_uniform("u_gamma", m_gamma);
        }
 
        float GammaCorrection::get_gamma() const
        {
            return m_gamma;
        }
 
        bool GammaCorrection::is_enabled()
        {
            return core::ServiceLocator<core::Config>::ref().get<bool>("gamma_correction", "graphics.effects");
        }
    } // namespace graphics
} // namespace galaxy