/**
* @author mrdoob / http://mrdoob.com/
*/
function absNumericalSort( a, b ) {
return Math.abs( b[ 1 ] ) - Math.abs( a[ 1 ] );
}
function WebGLMorphtargets( gl ) {
var influencesList = {};
var morphInfluences = new Float32Array( 8 );
function update( object, geometry, material, program ) {
var objectInfluences = object.morphTargetInfluences;
// When object doesn't have morph target influences defined, we treat it as a 0-length array
// This is important to make sure we set up morphTargetBaseInfluence / morphTargetInfluences
var length = objectInfluences === undefined ? 0 : objectInfluences.length;
var influences = influencesList[ geometry.id ];
if ( influences === undefined ) {
// initialise list
influences = [];
for ( var i = 0; i < length; i ++ ) {
influences[ i ] = [ i, 0 ];
}
influencesList[ geometry.id ] = influences;
}
var morphTargets = material.morphTargets && geometry.morphAttributes.position;
var morphNormals = material.morphNormals && geometry.morphAttributes.normal;
// Remove current morphAttributes
for ( var i = 0; i < length; i ++ ) {
var influence = influences[ i ];
if ( influence[ 1 ] !== 0 ) {
if ( morphTargets ) geometry.deleteAttribute( 'morphTarget' + i );
if ( morphNormals ) geometry.deleteAttribute( 'morphNormal' + i );
}
}
// Collect influences
for ( var i = 0; i < length; i ++ ) {
var influence = influences[ i ];
influence[ 0 ] = i;
influence[ 1 ] = objectInfluences[ i ];
}
influences.sort( absNumericalSort );
// Add morphAttributes
var morphInfluencesSum = 0;
for ( var i = 0; i < 8; i ++ ) {
var influence = influences[ i ];
if ( influence ) {
var index = influence[ 0 ];
var value = influence[ 1 ];
if ( value ) {
if ( morphTargets ) geometry.setAttribute( 'morphTarget' + i, morphTargets[ index ] );
if ( morphNormals ) geometry.setAttribute( 'morphNormal' + i, morphNormals[ index ] );
morphInfluences[ i ] = value;
morphInfluencesSum += value;
continue;
}
}
morphInfluences[ i ] = 0;
}
// GLSL shader uses formula baseinfluence * base + sum(target * influence)
// This allows us to switch between absolute morphs and relative morphs without changing shader code
// When baseinfluence = 1 - sum(influence), the above is equivalent to sum((target - base) * influence)
var morphBaseInfluence = geometry.morphTargetsRelative ? 1 : 1 - morphInfluencesSum;
program.getUniforms().setValue( gl, 'morphTargetBaseInfluence', morphBaseInfluence );
program.getUniforms().setValue( gl, 'morphTargetInfluences', morphInfluences );
}
return {
update: update
};
}
export { WebGLMorphtargets };