#version 330 core

in vec3 fragmentColor;
in vec3 fragNormal;
in vec3 fragVertex;

uniform mat4 model;
uniform vec3 light_position;
uniform mat3 normal_matrix;

out vec3 color;

void main()
{
	// https://www.tomdalling.com/blog/modern-opengl/06-diffuse-point-lighting
	vec3 normal = normalize(normal_matrix * fragNormal);

	vec3 fragPosition = vec3(model * vec4(fragVertex, 1));
	vec3 surfaceToLight = light_position - fragPosition;

	float brightness = dot(normal, surfaceToLight) / (length(surfaceToLight) * length(normal));
	brightness = clamp(brightness, 0, 1);

	color = brightness * fragmentColor;
}