Blinn-Phong

Bling-Phong model is extention of Phong Shading ( Basic shading) model.

Phong Shading ( Basic shading)is a great and very efficient approximation of lighting, but its specular reflections break down in certain conditions, specifically when the shininess property is low resulting in a large (rough) specular area.

out vec4 FragColor;
 
in vec3 fragPos;
in vec3 normal;
 
uniform vec3 lightPos;
uniform vec3 lightColor;
uniform vec3 objectColor;
uniform vec3 viewPos;
 
 
void main(){
	// ambient
	float ambientStrength = 0.1f;
	vec3 ambient = ambientStrength * lightColor;
	
	// diffuse
	vec3 norm = normalize(normal);
	vec3 lightDir = normalize(lightPos - fragPos);
	vec3 diff = max(dot(lightDir,norm),0.0f);
	vec3 diffuse = diff * lightColor;
	
	// specular
	float specularStrength = 0.5f;
	vec3 viewDir = normalize(viewPos - fragPos);
	// vec3 reflectDir = reflect(-lightDir,norm); this is for Phong lighting model for Bling_phon we use halfway Direction
	vec3 halfwayDir = normalize(lightDir + viewDir);
	vec3 spec = pow(max(dot(viewDir,halfwayDir),0.0f),32); // using halfwayDir instead of reflectDir for specular reflection.
	vec3 specular = spec * specularStrength * lightColor;
	
	
	vec3 result = (ambient + diffuse + specular) * objectColor;
	
	FragColor = vec4(result,1.0f);
}