Shader Learn

09 Drawing in several passes

Shadows: first draw a depth map from the light

The bottom left shows the depth the light “sees”. Where an object blocks the light, the ground gets a shadow.

Drag to rotate
-33
-0.0040.002
Explanation

Drag the underlined numbers left and right

renderer.shadowMap.enabled = true;light.castShadow = true;light.shadow.bias = ;mesh.castShadow = ;ground.receiveShadow = ;light.position.x = ;// in the shader, roughly:// float lit = myDepth - bias < mapDepth ? 1.0 : 0.0;
Shadow mapPass 1: view the scene from the light and record only depth. Pass 2: compare “my distance to the light” with the map.

Shadow = draw a depth map from the light first, then check whether “my distance to the light” is further than the map says.

Try it

  • Look at the bottom left: the light’s depth map
  • Set bias to 0: stripes appear on surfaces (shadow acne)
  • Turn off cast shadow