Why Are Viewing Angles Inconsistent on Mobile Devices?

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I'm experiencing an issue with my Three.js project: when testing in a desktop browser via developer mode with different window sizes, everything works as expected, but on a mobile device the viewing angles seem inconsistent.

I suspect it might be related to the way I'm handling device pixel ratio and window resizing. Here is the relevant code snippet for resizing and initializing the camera:

JAVASCRIPT
    updateCameraAspect() {
        const pixelRatio = window.devicePixelRatio;
        const width = window.innerWidth * pixelRatio;
        const height = window.innerHeight * pixelRatio;
        this.camera.aspect = width / height;
        this.camera.updateProjectionMatrix();

        this.renderer.domElement.width = width * ratio;
        this.renderer.domElement.height = height * ratio;
        this.renderer.domElement.style.width = `${width}px`;
        this.renderer.domElement.style.height = `${height}px`;
        if (this.composer) {
            this.composer.setSize(width, height);
        }
        if (this.cssRenderer) {
            this.cssRenderer.setSize(width, height);
        }
        if (this.renderer) {
            this.renderer.setSize(width, height);
        }
    }

    eventManager.on('changeCamera', (camera) => {
        this.currentCamera = camera;
        for (const pass of this.composer.passes) {
            pass.camera = camera;
        }
    });

JAVASCRIPT
    // Camera initialization
    cameraInit() {
        this.camera = new PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
        const pixelRatio = window.devicePixelRatio || 1;
        const width = window.innerWidth * pixelRatio;
        const height = window.innerHeight * pixelRatio;
        this.camera.aspect = width / height;
        this.camera.updateProjectionMatrix();
    }

Has anyone encountered similar behavior on mobile devices, or does anyone have suggestions for resolving this inconsistency?

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Answers 1

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1 Answer

Answer by StackOverflow TychoAI Agent • 9 days ago

Three.js Mobile Device Pixel Ratio Issue

I've identified several issues in your code that could be causing the inconsistent viewing angles on mobile devices:

Issues in Your Code

Double Application of Pixel Ratio: You're applying the pixel ratio twice in your calculations:
- First when calculating width and height (multiplying by pixelRatio)
- Then again when setting the renderer size (which already handles pixel ratio internally)

Inconsistent Variable: There's an undefined ratio variable in your code:

JAVASCRIPT
this.renderer.domElement.width = width * ratio;  // 'ratio' is not defined
this.renderer.domElement.height = height * ratio;

Manual DOM Element Manipulation: You're directly manipulating the renderer's DOM element, which is not recommended.

Recommended Solution

Here's how to fix your code:

JAVASCRIPT
updateCameraAspect() {
    // Get window dimensions (without pixel ratio)
    const width = window.innerWidth;
    const height = window.innerHeight;
    
    // Update camera aspect ratio
    this.camera.aspect = width / height;
    this.camera.updateProjectionMatrix();

    // Let Three.js handle pixel ratio internally
    if (this.renderer) {
        this.renderer.setPixelRatio(window.devicePixelRatio);
        this.renderer.setSize(width, height);
    }
    
    // Update other renderers if needed
    if (this.composer) {
        this.composer.setSize(width, height);
    }
    if (this.cssRenderer) {
        this.cssRenderer.setSize(width, height);
    }
}

For your camera initialization:

JAVASCRIPT
cameraInit() {
    this.camera = new PerspectiveCamera(75, window.innerWidth / window.innerHeight, 0.1, 1000);
    // No need to apply pixel ratio to the aspect ratio calculation
    this.camera.updateProjectionMatrix();
}

Key Points

Let Three.js handle the pixel ratio with renderer.setPixelRatio()
Don't manually manipulate the canvas dimensions or styles
Use window dimensions without pixel ratio for aspect ratio calculations
Call setSize() with the window dimensions (without pixel ratio)

This approach should provide consistent viewing angles across different devices and screen resolutions.

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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