attribute vec3 aVertexPosition;

attribute vec3 aVertexNormal;

attribute vec2 aTextureCoord;

uniform mat4 uMVMatrix;

uniform mat4 uPMatrix;

uniform mat3 uNMatrix;

uniform vec3 uAmbientColor;

uniform vec3 uLightingDirection;

uniform vec3 uDirectionalColor;

uniform bool uUseLighting;

varying vec2 vTextureCoord;

varying vec3 vLightWeighting;

void main(void) {

gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);

vTextureCoord = aTextureCoord;

if (!uUseLighting) {

vLightWeighting = vec3(1.0, 1.0, 1.0);

} else {

vec3 transformedNormal = uNMatrix * aVertexNormal;

float directionalLightWeighting = max(dot(transformedNormal, uLightingDirection), 0.0);

vLightWeighting = uAmbientColor + uDirectionalColor * directionalLightWeighting;

}

}