#type vertex
#version 430

layout(location = 0) in vec3 a_Position;
layout(location = 1) in vec2 a_TexCoord;

out vec2 v_TexCoord;

void main()
{
    vec4 position = vec4(a_Position.xy, 0.0, 1.0);
    v_TexCoord = a_TexCoord;
    gl_Position = position;
}

#type fragment
#version 430

layout(location = 0) out vec4 o_Color;

in vec2 v_TexCoord;

uniform sampler2D u_SceneTexture;
uniform sampler2D u_BloomTexture;

uniform float u_Exposure;
uniform bool u_EnableBloom;

void main()
{
#if 1
    const float gamma     = 2.2;
    const float pureWhite = 1.0;

    // Tonemapping
    vec3 color = texture(u_SceneTexture, v_TexCoord).rgb;
    if (u_EnableBloom)
    {
        vec3 bloomColor = texture(u_BloomTexture, v_TexCoord).rgb;
        color += bloomColor;
    }

    // Reinhard tonemapping
    float luminance = dot(color, vec3(0.2126, 0.7152, 0.0722));
    float mappedLuminance = (luminance * (1.0 + luminance / (pureWhite * pureWhite))) / (1.0 + luminance);

    // Scale color by ratio of average luminances.
    vec3 mappedColor = (mappedLuminance / luminance) * color* u_Exposure;

    // Gamma correction.
    o_Color = vec4(mappedColor, 1.0);
#else
    const float gamma = 2.2;
    vec3 hdrColor = texture(u_SceneTexture, v_TexCoord).rgb;
    vec3 bloomColor = texture(u_BloomTexture, v_TexCoord).rgb;
    hdrColor += bloomColor; // additive blending
    // tone mapping
    vec3 result = vec3(1.0) - exp(-hdrColor * u_Exposure);
    // also gamma correct while we're at it
    result = pow(result, vec3(1.0 / gamma));
    o_Color = vec4(result, 1.0);
#endif
}