Source

LWJGL Shader Tutorials / src / main / java / com / ra4king / opengl / arcsynthesis / gl33 / chapter11 / example2 / example11.2.BlinnLighting.frag

#version 330

in vec4 diffuseColor;
in vec3 vertexNormal;
in vec3 cameraSpacePosition;

out vec4 outputColor;

uniform vec4 lightIntensity;
uniform vec4 ambientIntensity;

uniform vec3 cameraSpaceLightPos;

uniform float lightAttenuation;

const vec4 specularColor = vec4(0.25, 0.25, 0.25, 1.0);
uniform float shininessFactor;

float CalcAttenuation(in vec3 cameraSpacePosition, out vec3 lightDirection)
{
	vec3 lightDifference = cameraSpaceLightPos - cameraSpacePosition;
	float lightDistanceSqr = dot(lightDifference, lightDifference);
	lightDirection = lightDifference * inversesqrt(lightDistanceSqr);
	
	return 1.0/ (1.0 + lightAttenuation * sqrt(lightDistanceSqr));
}

void main() {
	vec3 lightDir = vec3(0.0);
	float atten = CalcAttenuation(cameraSpacePosition, lightDir);
	vec4 attenIntensity = atten * lightIntensity;
	
	vec3 surfaceNormal = normalize(vertexNormal);
	float cosAngIncidence = dot(surfaceNormal, lightDir);
	cosAngIncidence = clamp(cosAngIncidence, 0.0, 1.0);
	
	vec3 viewDirection = normalize(-cameraSpacePosition);
	
	vec3 halfAngle = normalize(lightDir + viewDirection);
	float blinnTerm = dot(surfaceNormal, halfAngle);
	blinnTerm = clamp(blinnTerm, 0.0, 1.0);
	blinnTerm = cosAngIncidence != 0.0 ? blinnTerm : 0.0;
	blinnTerm = pow(blinnTerm, shininessFactor);
	
	outputColor = diffuseColor  * attenIntensity * cosAngIncidence +
				  specularColor * attenIntensity * blinnTerm 	   +
				  diffuseColor  * ambientIntensity;
}