import { add, mul, div } from '../math/OperatorNode.js';
import { floor, ceil, fract, pow } from '../math/MathNode.js';
import { Fn, float, vec2, vec4, int } from '../tsl/TSLBase.js';
/** @module TextureBicubic **/
// Mipped Bicubic Texture Filtering by N8
// https://www.shadertoy.com/view/Dl2SDW
const bC = 1.0 / 6.0;
const w0 = ( a ) => mul( bC, mul( a, mul( a, a.negate().add( 3.0 ) ).sub( 3.0 ) ).add( 1.0 ) );
const w1 = ( a ) => mul( bC, mul( a, mul( a, mul( 3.0, a ).sub( 6.0 ) ) ).add( 4.0 ) );
const w2 = ( a ) => mul( bC, mul( a, mul( a, mul( - 3.0, a ).add( 3.0 ) ).add( 3.0 ) ).add( 1.0 ) );
const w3 = ( a ) => mul( bC, pow( a, 3 ) );
const g0 = ( a ) => w0( a ).add( w1( a ) );
const g1 = ( a ) => w2( a ).add( w3( a ) );
// h0 and h1 are the two offset functions
const h0 = ( a ) => add( - 1.0, w1( a ).div( w0( a ).add( w1( a ) ) ) );
const h1 = ( a ) => add( 1.0, w3( a ).div( w2( a ).add( w3( a ) ) ) );
const bicubic = ( textureNode, texelSize, lod ) => {
const uv = textureNode.uvNode;
const uvScaled = mul( uv, texelSize.zw ).add( 0.5 );
const iuv = floor( uvScaled );
const fuv = fract( uvScaled );
const g0x = g0( fuv.x );
const g1x = g1( fuv.x );
const h0x = h0( fuv.x );
const h1x = h1( fuv.x );
const h0y = h0( fuv.y );
const h1y = h1( fuv.y );
const p0 = vec2( iuv.x.add( h0x ), iuv.y.add( h0y ) ).sub( 0.5 ).mul( texelSize.xy );
const p1 = vec2( iuv.x.add( h1x ), iuv.y.add( h0y ) ).sub( 0.5 ).mul( texelSize.xy );
const p2 = vec2( iuv.x.add( h0x ), iuv.y.add( h1y ) ).sub( 0.5 ).mul( texelSize.xy );
const p3 = vec2( iuv.x.add( h1x ), iuv.y.add( h1y ) ).sub( 0.5 ).mul( texelSize.xy );
const a = g0( fuv.y ).mul( add( g0x.mul( textureNode.sample( p0 ).level( lod ) ), g1x.mul( textureNode.sample( p1 ).level( lod ) ) ) );
const b = g1( fuv.y ).mul( add( g0x.mul( textureNode.sample( p2 ).level( lod ) ), g1x.mul( textureNode.sample( p3 ).level( lod ) ) ) );
return a.add( b );
};
/**
* Applies mipped bicubic texture filtering to the given texture node.
*
* @method
* @param {TextureNode} textureNode - The texture node that should be filtered.
* @param {Node<float>} [lodNode=float(3)] - Defines the LOD to sample from.
* @return {Node} The filtered texture sample.
*/
export const textureBicubic = /*@__PURE__*/ Fn( ( [ textureNode, lodNode = float( 3 ) ] ) => {
const fLodSize = vec2( textureNode.size( int( lodNode ) ) );
const cLodSize = vec2( textureNode.size( int( lodNode.add( 1.0 ) ) ) );
const fLodSizeInv = div( 1.0, fLodSize );
const cLodSizeInv = div( 1.0, cLodSize );
const fSample = bicubic( textureNode, vec4( fLodSizeInv, fLodSize ), floor( lodNode ) );
const cSample = bicubic( textureNode, vec4( cLodSizeInv, cLodSize ), ceil( lodNode ) );
return fract( lodNode ).mix( fSample, cSample );
} );