// ----------------------------------------------------------------

// From Game Programming in C++ by Sanjay Madhav

// Copyright (C) 2017 Sanjay Madhav. All rights reserved.

//

// Released under the BSD License

// See LICENSE in root directory for full details.

// ----------------------------------------------------------------

// Request GLSL 3.3

#version 330

// Inputs from vertex shader

// Tex coord

in vec2 fragTexCoord;

// This corresponds to the output color to the color buffer

layout(location = 0) out vec4 outColor;

// Different textures from G-buffer

uniform sampler2D uGDiffuse;

uniform sampler2D uGNormal;

uniform sampler2D uGWorldPos;

// Create a struct for directional light

struct DirectionalLight

{

// Direction of light

vec3 mDirection;

// Diffuse color

vec3 mDiffuseColor;

// Specular color

vec3 mSpecColor;

};

// Uniforms for lighting

// Camera position (in world space)

uniform vec3 uCameraPos;

// Ambient light level

uniform vec3 uAmbientLight;

// Directional Light

uniform DirectionalLight uDirLight;

void main()

{

vec3 gbufferDiffuse = texture(uGDiffuse, fragTexCoord).xyz;

vec3 gbufferNorm = texture(uGNormal, fragTexCoord).xyz;

vec3 gbufferWorldPos = texture(uGWorldPos, fragTexCoord).xyz;

// Surface normal

vec3 N = normalize(gbufferNorm);

// Vector from surface to light

vec3 L = normalize(-uDirLight.mDirection);

// Vector from surface to camera

vec3 V = normalize(uCameraPos - gbufferWorldPos);

// Reflection of -L about N

vec3 R = normalize(reflect(-L, N));

// Compute phong reflection

vec3 Phong = uAmbientLight;

float NdotL = dot(N, L);

if (NdotL > 0)

{

vec3 Diffuse = uDirLight.mDiffuseColor * dot(N, L);

}

// Clamp light between 0-1 RGB values

Phong = clamp(Phong, 0.0, 1.0);

// Final color is texture color times phong light (alpha = 1)

outColor = vec4(gbufferDiffuse * Phong, 1.0);

}