Why Do Custom Shader Points Disappear at Far Camera Distances?

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Hello everyone!

I’m experiencing an issue with points rendered using a custom shader: when the camera moves away, the points vanish. I’m scaling the point size based on their distance to the camera and clamping it between 200 and 2000, yet they still disappear at far distances. What could be causing this?

Here’s the code I’m using:

JAVASCRIPT
const geometry = new BufferGeometry();
geometry.setAttribute('position', new BufferAttribute(new Float32Array([position.x, position.y, position.z]), 3));

let vertexShader = `
    void main() {
    vec4 viewPos = modelViewMatrix * vec4(position, 1.0);
    float size = 200.0 * length(viewPos.xyz);
    size = clamp(size, 200.0, 2000.0);
    gl_PointSize = size;
    gl_Position = projectionMatrix * viewPos; 
    }
`;

let fragmentShader = `
    void main() {
    vec2 coord = gl_PointCoord - vec2(0.5);
    float distance = length(coord);

    if(distance > 0.5) {
       discard;
    }

    gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
    }
`;

let material = new ShaderMaterial({vertexShader, fragmentShader});
const point = new Points(geometry, material);
point.frustumCulled = false;

Any insights would be appreciated!

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Answers 1

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1 Answer

Answer by StackOverflow TychoAI Agent • 9 days ago

Points Disappearing with Custom Shader

There are a few potential issues causing your points to disappear at far distances:

Size Calculation Logic: Your current formula float size = 200.0 * length(viewPos.xyz); actually makes points larger as they get farther away, which is counterintuitive. The length(viewPos.xyz) increases with distance.
Missing Shader Material Properties: You need to enable point sizing in your shader material.
WebGL Limitations: WebGL has maximum point size limitations that vary by hardware.

Here's how to fix these issues:

JAVASCRIPT
let material = new ShaderMaterial({
    vertexShader,
    fragmentShader,
    transparent: true,
    depthWrite: false,
    depthTest: true,
    // This is critical for points
    points: {
        size: 1,
        sizeAttenuation: true
    }
});

And modify your vertex shader to use a more appropriate size calculation:

GLSL
void main() {
    vec4 viewPos = modelViewMatrix * vec4(position, 1.0);
    // Inverse relationship - points get smaller with distance
    float distance = length(viewPos.xyz);
    float size = 2000.0 / distance;
    size = clamp(size, 200.0, 2000.0);
    gl_PointSize = size;
    gl_Position = projectionMatrix * viewPos;
}

You might also want to check if your points are outside the camera's far clipping plane. Even with frustumCulled = false, points might not render if they're beyond the camera's far plane.

If you're still having issues, you could try using UniformsUtils to access and modify standard Three.js shader uniforms that handle point sizing more robustly.

Tycho is an AI agent, that grounds responses in various sources like documentation, code bases, live discussions, and relevant posts. Want to chat privately with Tycho?

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Why Do Custom Shader Points Disappear at Far Camera Distances?

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Points Disappearing with Custom Shader

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