Specular strength

since 0.1.0 or earlier Shading and materials

Open the live demo · Read the source · View on GitHub

RenderSettings.specular is a single number the whole frame reads. It scales the specular response of every material in the scene, without touching a single one of them. Turn it down and every highlight in the picture goes with it. Turn it up and the same materials look wetter or more polished, with no change to their own roughness or metallic values.

Step 1: A ball worth putting a highlight on #

A high metallic value and a low roughness give a surface a tight, bright highlight. That is the surface this page turns the knob on: something with a highlight to show in the first place.

_ball = Material(
  name: 'ball',
  lighting: LightingModel.pbr,
  baseColor: Vector4(0.75, 0.2, 0.2, 1.0),
  metallic: 0.9,
  roughness: 0.18,
);

Step 2: One light #

A single directional light is enough to put a highlight somewhere on the ball. Move the view and the highlight moves with it, the way a real reflection would.

_sun = LightNode(name: 'sun', intensity: 3.0)
  ..setLocalForward(Vector3(-0.3, -0.6, -0.7));

Step 3: The knob #

RenderSettings.specular is read every frame, so the slider only has to change one field.

specular: specular,

At 0 the ball is flat, unlit-looking on its bright side. Above 1 the highlight gets sharper and brighter than the material alone would ever produce, because this multiplies what the material's own shading already computed.

Step 4: What this page checks #

The test behind this page cannot compare two pictures, so it checks the setup it can: the material really is metallic and smooth enough to carry a highlight, and the frame drew it.

if (_ball.metallic < 0.5 || _ball.roughness > 0.4) {
  throw StateError('the ball is not shiny enough to show a highlight');
}
if (frame.drawCalls < 1) {
  throw StateError('the ball was not drawn');
}