// G-BUFFER

#ifndef UNLIT
// - Position in view space
uniform sampler2DRect positionBuffer;
// - Albedo + Roughness
uniform sampler2DRect albedoBuffer;
// - Normal buffer
uniform sampler2DRect normalBuffer;
#endif
// - Emission + Metallic
uniform sampler2DRect emissionBuffer;

// LIGHT ATTRIBUTES
#ifdef AMBIENT_LIGHT
uniform samplerCube ambientMap;
uniform samplerCube reflectMap;
uniform sampler2D brdfLUT;
uniform mat3 inverseViewMatrix;
#elif !defined UNLIT
uniform vec3 lightColor;
#endif

#ifdef SHADOWMAP
#ifdef POINT_LIGHT
uniform samplerCube shadowMap;
uniform mat3 inverseViewMatrix;
#else
uniform sampler2DShadow shadowMap;
uniform mat4 viewToLightMatrix;
#endif
#endif

#if defined POINT_LIGHT
uniform vec3 pointLight;
uniform float range;
#elif defined DIRECTIONNAL_LIGHT
uniform vec3 dirLight;
#elif defined SPOT_LIGHT
uniform vec3 pointLight;
uniform float attenuation;
uniform vec3 dirLight;
uniform float cutoff;
#endif

// FRAGMENT POSITIONNING

in vec2 screenPos;

uniform mat4 inverseProjectionMatrix;

// OUTPUT LIGHT

layout(location = 0)out vec4 outColor;

// MAIN PROGRAM

void main(void) {
    // get fragment information from the G-Buffer
    ivec2 texCoord = ivec2(gl_FragCoord.xy);
#ifdef UNLIT
    outColor = vec4(texelFetch(emissionBuffer, texCoord).rgb, 1);
#else
    vec3 normal = texelFetch(normalBuffer, texCoord).xyz;
    vec4 albedoTexel = texelFetch(albedoBuffer, texCoord);
    vec3 albedo = albedoTexel.rgb;
    float roughness = albedoTexel.a;
    vec4 emissionTexel = texelFetch(emissionBuffer, texCoord);
    vec3 emission = emissionTexel.rgb;
    float metallic = emissionTexel.a;
    vec4 fragPos = texelFetch(positionBuffer, texCoord);

    // compute shadow
#ifdef SHADOWMAP
    #ifdef POINT_LIGHT
    float shadow = 1;
    #else
    vec4 fragInLightSpace = viewToLightMatrix * fragPos;
    fragInLightSpace.z = fragInLightSpace.z - 0.002;
    float shadow = texture(shadowMap, fragInLightSpace.xyz/fragInLightSpace.w);
    #endif
#else
    float shadow = 1;
#endif

    float att = 1;
#ifdef POINT_LIGHT
    vec3 dirLight = pointLight - fragPos.xyz;
    //vec4 pointShadowParam = vec4(inverseViewMatrix * dirLight, length(dirLight));
    //att = texture(shadowMap, pointShadowParam);
    //outColor = vec4(vec3(texture(shadowMap, vec4(inverseViewMatrix * dirLight, length(dirLight)/range))), 1);
    //outColor = vec4(vec3(texture(shadowMap, vec3(inverseViewMatrix * dirLight)).r), 1);
    //outColor = vec4(vec3(length(dirLight)/range), 1);
    //return;
    float dist = length(dirLight);
    att = clamp(1 - dist/range, 0, 1);
    dirLight = normalize(dirLight);
#endif

    vec3 viewDir = normalize(-fragPos.xyz);
#ifdef AMBIENT_LIGHT
    vec3 ambientLight = ambientGGX(albedo, metallic, roughness, normal, viewDir, inverseViewMatrix, ambientMap, reflectMap, brdfLUT);
    outColor = vec4(emission + ambientLight, 1);
#else
    vec3 halfVec = normalize(viewDir + dirLight);
    vec3 light = GGX(albedo, metallic, roughness, lightColor, normal, dirLight, halfVec, viewDir);
    outColor = vec4(mix(vec3(0.0), light*shadow, att*att), 1);
#endif

#endif // UNLIT
}