07 Surfaces and light

dot: the simplest lighting

The more a surface faces the light, the larger the dot product, the brighter it is.

Light direction X-0.60

-22

Light direction Y0.80

-22

Ambient0.12

00.5

Runs once per pixelDrag numbers, or edit the code

void main() {
  vec3 normal = normalize(vNormal);
  vec3 light = normalize(vec3(-0.600, 0.800, 1.0));
  float diffuse = max(dot(normal, light), 0.0);
  vec3 color = vec3(0.96, 0.43, 0.30) * (0.120 + diffuse * (1.0 - 0.120));
  gl_FragColor = vec4(color, 1.0);
}

void main() {
  vec3 normal = normalize(vNormal);
  vec3 light = normalize(vec3(-0.600, 0.800, 1.0));
  float diffuse = max(dot(normal, light), 0.0);
  vec3 color = vec3(0.96, 0.43, 0.30) * (0.120 + diffuse * (1.0 - 0.120));
  gl_FragColor = vec4(color, 1.0);
}

JS sidegl.uniformMatrix4fv(uModel, …) // rotation -0.35 / 0.10

The dot of two unit vectors is the cosine of their angle; max(dot(N, L), 0) is Lambert diffuse lighting.

Try it

Move the light behind the object
Set ambient to 0: the unlit side goes fully black