three 基础库
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/**
* Based on Nvidia Cg tutorial
*/
const FresnelShader = {
uniforms: {
'mRefractionRatio': { value: 1.02 },
'mFresnelBias': { value: 0.1 },
'mFresnelPower': { value: 2.0 },
'mFresnelScale': { value: 1.0 },
'tCube': { value: null }
},
vertexShader: /* glsl */`
uniform float mRefractionRatio;
uniform float mFresnelBias;
uniform float mFresnelScale;
uniform float mFresnelPower;
varying vec3 vReflect;
varying vec3 vRefract[3];
varying float vReflectionFactor;
void main() {
vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 );
vec4 worldPosition = modelMatrix * vec4( position, 1.0 );
vec3 worldNormal = normalize( mat3( modelMatrix[0].xyz, modelMatrix[1].xyz, modelMatrix[2].xyz ) * normal );
vec3 I = worldPosition.xyz - cameraPosition;
vReflect = reflect( I, worldNormal );
vRefract[0] = refract( normalize( I ), worldNormal, mRefractionRatio );
vRefract[1] = refract( normalize( I ), worldNormal, mRefractionRatio * 0.99 );
vRefract[2] = refract( normalize( I ), worldNormal, mRefractionRatio * 0.98 );
vReflectionFactor = mFresnelBias + mFresnelScale * pow( 1.0 + dot( normalize( I ), worldNormal ), mFresnelPower );
gl_Position = projectionMatrix * mvPosition;
}`,
fragmentShader: /* glsl */`
uniform samplerCube tCube;
varying vec3 vReflect;
varying vec3 vRefract[3];
varying float vReflectionFactor;
void main() {
vec4 reflectedColor = textureCube( tCube, vec3( -vReflect.x, vReflect.yz ) );
vec4 refractedColor = vec4( 1.0 );
refractedColor.r = textureCube( tCube, vec3( -vRefract[0].x, vRefract[0].yz ) ).r;
refractedColor.g = textureCube( tCube, vec3( -vRefract[1].x, vRefract[1].yz ) ).g;
refractedColor.b = textureCube( tCube, vec3( -vRefract[2].x, vRefract[2].yz ) ).b;
gl_FragColor = mix( refractedColor, reflectedColor, clamp( vReflectionFactor, 0.0, 1.0 ) );
}`
};
export { FresnelShader };