three 基础库
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( function () {
const LUTShader = {
defines: {
USE_3DTEXTURE: 1
},
uniforms: {
lut3d: {
value: null
},
lut: {
value: null
},
lutSize: {
value: 0
},
tDiffuse: {
value: null
},
intensity: {
value: 1.0
}
},
vertexShader:
/* glsl */
`
varying vec2 vUv;
void main() {
vUv = uv;
gl_Position = projectionMatrix * modelViewMatrix * vec4( position, 1.0 );
}
`,
fragmentShader:
/* glsl */
`
uniform float lutSize;
#if USE_3DTEXTURE
precision highp sampler3D;
uniform sampler3D lut3d;
#else
uniform sampler2D lut;
vec3 lutLookup( sampler2D tex, float size, vec3 rgb ) {
float sliceHeight = 1.0 / size;
float yPixelHeight = 1.0 / ( size * size );
// Get the slices on either side of the sample
float slice = rgb.b * size;
float interp = fract( slice );
float slice0 = slice - interp;
float centeredInterp = interp - 0.5;
float slice1 = slice0 + sign( centeredInterp );
// Pull y sample in by half a pixel in each direction to avoid color
// bleeding from adjacent slices.
float greenOffset = clamp( rgb.g * sliceHeight, yPixelHeight * 0.5, sliceHeight - yPixelHeight * 0.5 );
vec2 uv0 = vec2(
rgb.r,
slice0 * sliceHeight + greenOffset
);
vec2 uv1 = vec2(
rgb.r,
slice1 * sliceHeight + greenOffset
);
vec3 sample0 = texture2D( tex, uv0 ).rgb;
vec3 sample1 = texture2D( tex, uv1 ).rgb;
return mix( sample0, sample1, abs( centeredInterp ) );
}
#endif
varying vec2 vUv;
uniform float intensity;
uniform sampler2D tDiffuse;
void main() {
vec4 val = texture2D( tDiffuse, vUv );
vec4 lutVal;
// pull the sample in by half a pixel so the sample begins
// at the center of the edge pixels.
float pixelWidth = 1.0 / lutSize;
float halfPixelWidth = 0.5 / lutSize;
vec3 uvw = vec3( halfPixelWidth ) + val.rgb * ( 1.0 - pixelWidth );
#if USE_3DTEXTURE
lutVal = vec4( texture( lut3d, uvw ).rgb, val.a );
#else
lutVal = vec4( lutLookup( lut, lutSize, uvw ), val.a );
#endif
gl_FragColor = vec4( mix( val, lutVal, intensity ) );
}
`
};
class LUTPass extends THREE.ShaderPass {
set lut( v ) {
const material = this.material;
if ( v !== this.lut ) {
material.uniforms.lut3d.value = null;
material.uniforms.lut.value = null;
if ( v ) {
const is3dTextureDefine = v.isDataTexture3D ? 1 : 0;
if ( is3dTextureDefine !== material.defines.USE_3DTEXTURE ) {
material.defines.USE_3DTEXTURE = is3dTextureDefine;
material.needsUpdate = true;
}
material.uniforms.lutSize.value = v.image.width;
if ( v.isDataTexture3D ) {
material.uniforms.lut3d.value = v;
} else {
material.uniforms.lut.value = v;
}
}
}
}
get lut() {
return this.material.uniforms.lut.value || this.material.uniforms.lut3d.value;
}
set intensity( v ) {
this.material.uniforms.intensity.value = v;
}
get intensity() {
return this.material.uniforms.intensity.value;
}
constructor( options = {} ) {
super( LUTShader );
this.lut = options.lut || null;
this.intensity = 'intensity' in options ? options.intensity : 1;
}
}
THREE.LUTPass = LUTPass;
} )();