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()
?
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: