Three.js-鱼眼效果 [英] Three.js - Fisheye effect

问题描述

因此，我搞砸了

So, I've messed around with three.js, works out great. The only thing I can't figure out, is how to make a camera with a real fisheye effect.

How is that possible? camera.setLens()?

解决方案

The fish eye effect can be achieved using Giliam de Carpentier's shader for lens distortion.

Shader code:

function getDistortionShaderDefinition()
{
    return {

        uniforms: {
            "tDiffuse":         { type: "t", value: null },
            "strength":         { type: "f", value: 0 },
            "height":           { type: "f", value: 1 },
            "aspectRatio":      { type: "f", value: 1 },
            "cylindricalRatio": { type: "f", value: 1 }
        },

        vertexShader: [
            "uniform float strength;",          // s: 0 = perspective, 1 = stereographic
            "uniform float height;",            // h: tan(verticalFOVInRadians / 2)
            "uniform float aspectRatio;",       // a: screenWidth / screenHeight
            "uniform float cylindricalRatio;",  // c: cylindrical distortion ratio. 1 = spherical

            "varying vec3 vUV;",                // output to interpolate over screen
            "varying vec2 vUVDot;",             // output to interpolate over screen

            "void main() {",
                "gl_Position = projectionMatrix * (modelViewMatrix * vec4(position, 1.0));",

                "float scaledHeight = strength * height;",
                "float cylAspectRatio = aspectRatio * cylindricalRatio;",
                "float aspectDiagSq = aspectRatio * aspectRatio + 1.0;",
                "float diagSq = scaledHeight * scaledHeight * aspectDiagSq;",
                "vec2 signedUV = (2.0 * uv + vec2(-1.0, -1.0));",

                "float z = 0.5 * sqrt(diagSq + 1.0) + 0.5;",
                "float ny = (z - 1.0) / (cylAspectRatio * cylAspectRatio + 1.0);",

                "vUVDot = sqrt(ny) * vec2(cylAspectRatio, 1.0) * signedUV;",
                "vUV = vec3(0.5, 0.5, 1.0) * z + vec3(-0.5, -0.5, 0.0);",
                "vUV.xy += uv;",
            "}"
        ].join("\n"),

        fragmentShader: [
            "uniform sampler2D tDiffuse;",      // sampler of rendered scene?s render target
            "varying vec3 vUV;",                // interpolated vertex output data
            "varying vec2 vUVDot;",             // interpolated vertex output data

            "void main() {",
                "vec3 uv = dot(vUVDot, vUVDot) * vec3(-0.5, -0.5, -1.0) + vUV;",
                "gl_FragColor = texture2DProj(tDiffuse, uv);",
            "}"
        ].join("\n")

    };
}

One way to setup the effect using effect composer (assuming scene and renderer have been been created):

// Create camera
camera = new THREE.PerspectiveCamera( 100, window.innerWidth / window.innerHeight, 1, 1000000 );
camera.position.z = 800;

// Create effect composer
composer = new THREE.EffectComposer( renderer );
composer.addPass( new THREE.RenderPass( scene, camera ) );

// Add distortion effect to effect composer
var effect = new THREE.ShaderPass( getDistortionShaderDefinition() );
composer.addPass( effect );
effect.renderToScreen = true;

// Setup distortion effect
var horizontalFOV = 140;
var strength = 0.5;
var cylindricalRatio = 2;
var height = Math.tan(THREE.Math.degToRad(horizontalFOV) / 2) / camera.aspect;

camera.fov = Math.atan(height) * 2 * 180 / 3.1415926535;
camera.updateProjectionMatrix();

effect.uniforms[ "strength" ].value = strength;
effect.uniforms[ "height" ].value = height;
effect.uniforms[ "aspectRatio" ].value = camera.aspect;
effect.uniforms[ "cylindricalRatio" ].value = cylindricalRatio;

Following script are needed and they can be found for example from three.js GitHub page:

<script src="examples/js/postprocessing/EffectComposer.js"></script>
<script src="examples/js/postprocessing/RenderPass.js"></script>
<script src="examples/js/postprocessing/MaskPass.js"></script>
<script src="examples/js/postprocessing/ShaderPass.js"></script>
<script src="examples/js/shaders/CopyShader.js"></script>

Link to Giliam's example: http://www.decarpentier.nl/downloads/lensdistortion-webgl/lensdistortion-webgl.html

Link to Giliam's article about lens distortion: http://www.decarpentier.nl/lens-distortion

Image of my test where lens distortion effect is used:

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