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

// 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;

// Normal (in world space)

in vec3 fragNormal;

// Position (in world space)

in vec3 fragWorldPos;

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

out vec4 outColor;

// This is used for the texture sampling

uniform sampler2D uTexture;

// 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;

// Specular power for this surface

uniform float uSpecPower;

// Ambient light level

uniform vec3 uAmbientLight;

// Directional Light

uniform DirectionalLight uDirLight;

void main()

{

// Surface normal

vec3 N = normalize(fragNormal);

// Vector from surface to light

vec3 L = normalize(-uDirLight.mDirection);

// Vector from surface to camera

vec3 V = normalize(uCameraPos - fragWorldPos);

// 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 * NdotL;

vec3 Specular = uDirLight.mSpecColor * pow(max(0.0, dot(R, V)), uSpecPower);

Phong += Diffuse + Specular;

}

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

outColor = texture(uTexture, fragTexCoord) * vec4(Phong, 1.0f);

}