<!-- NEW5 — TEST 5 · THE BEND AT THE HEART · part 371 -->
onst glFragmentShader = WebGLShader( gl, gl.FRAGMENT_SHADER, fragmentGlsl );

	gl.attachShader( program, glVertexShader );
	gl.attachShader( program, glFragmentShader );

	// Force a particular attribute to index 0.

	if ( parameters.index0AttributeName !== undefined ) {

		gl.bindAttribLocation( program, 0, parameters.index0AttributeName );

	} else if ( parameters.hasPositionAttribute === true ) {

		// below avoids the "Attribute 0 is disabled" performance penalty

		gl.bindAttribLocation( program, 0, 'position' );

	}

	gl.linkProgram( program );

	function onFirstUse( self ) {

		// check for link errors
		if ( renderer.debug.checkShaderErrors ) {

			const programInfoLog = gl.getProgramInfoLog( program ) || '';
			const vertexShaderInfoLog = gl.getShaderInfoLog( glVertexShader ) || '';
			const fragmentShaderInfoLog = gl.getShaderInfoLog( glFragmentShader ) || '';

			const programLog = programInfoLog.trim();
			const vertexLog = vertexShaderInfoLog.trim();
			const fragmentLog = fragmentShaderInfoLog.trim();

			let runnable = true;
			let haveDiagnostics = true;

			if ( gl.getProgramParameter( program, gl.LINK_STATUS ) === false ) {

				runnable = false;

				if ( typeof renderer.debug.onShaderError === 'function' ) {

					renderer.debug.onShaderError( gl, program, glVertexShader, glFragmentShader );

				} else {

					// default error reporting

					const vertexErrors = getShaderErrors( gl, glVertexShader, 'vertex' );
					const fragmentErrors = getShaderErrors( gl, glFragmentShader, 'fragment' );

					error(
						'WebGLProgram: Shader Error ' + gl.getError() + ' - ' +
						'VALIDATE_STATUS ' + gl.getProgramParameter( program, gl.VALIDATE_STATUS ) + '\n\n' +
						'Material Name: ' + self.name + '\n' +
						'Material Type: ' + self.type + '\n\n' +
						'Program Info Log: ' + programLog + '\n' +
						vertexErrors + '\n' +
						fragmentErrors
					);

				}

			} else if ( programLog !== '' ) {

				warn( 'WebGLProgram: Program Info Log:', programLog );

			} else if ( vertexLog === '' || fragmentLog === '' ) {

				haveDiagnostics = false;

			}

			if ( haveDiagnostics ) {

				self.diagnostics = {

					runnable: runnable,

					programLog: programLog,

					vertexShader: {

						log: vertexLog,
						prefix: prefixVertex

					},

					fragmentShader: {

						log: fragmentLog,
						prefix: prefixFragment

					}

				};

			}

		}

		// Clean up

		// Crashes in iOS9 and iOS10. #18402
		// gl.detachShader( program, glVertexShader );
		// gl.detachShader( program, glFragmentShader );

		gl.deleteShader( glVertexShader );
		gl.deleteShader( glFragmentShader );

		cachedUniforms = new WebGLUniforms( gl, program );
		cachedAttributes = fetchAttributeLocations( gl, program );

	}

	// set up caching for uniform locations

	let cachedUniforms;

	this.getUniforms = function () {

		if ( cachedUniforms === undefined ) {

			// Populates cachedUniforms and cachedAttributes
			onFirstUse( this );

		}

		return cachedUniforms;

	};

	// set up caching for attribute locations

	let cachedAttributes;

	this.getAttributes = function () {

		if ( cachedAttributes === undefined ) {

			// Populates cachedAttributes and cachedUniforms
			onFirstUse( this );

		}

		return cachedAttributes;

	};

	// indicate when the program is ready to be used. if the KHR_parallel_shader_compile extension isn't supported,
	// flag the program as ready immediately. It may cause a stall when it's first used.

	let programReady = ( parameters.rendererExtensionParallelShaderCompile === false );

	this.isReady = function () {

		if ( programReady === false ) {

			programReady = gl.getProgramParameter( program, COMPLETION_STATUS_KHR );

		}

		return programReady;

	};

	// free resource

	this.destroy = function () {

		bindingStates.releaseStatesOfProgram( this );

		gl.deleteProgram( program );
		this.program = undefined;

	};

	//

	this.type = parameters.shaderType;
	this.name = parameters.shaderName;
	this.id = programIdCount ++;
	this.cacheKey = cacheKey;
	this.usedTimes = 1;
	this.program = program;
	this.vertexShader = glVertexShader;
	this.fragmentShader = glFragmentShader;

	return this;

}

let _id = 0;

class WebGLShaderCache {

	constructor() {

		this.shaderCache = new Map();
		this.materialCache = new Map();

	}

	update( material, vertexShaderStage, fragmentShaderStage ) {

		const materialShaders = this._getShaderCacheForMaterial( material );

		if ( materialShaders.has( vertexShaderStage ) === false ) {

			materialShaders.add( vertexShaderStage );
			vertexShaderStage.usedTimes ++;

		}

		if ( materialShaders.has( fragmentShaderStage ) === false ) {

			materialShaders.add( fragmentShaderStage );
			fragmentShaderStage.usedTimes ++;

		}

		return this;

	}

	remove( material ) {

		const materialShaders = this.materialCache.get( material );

		for ( const shaderStage of materialShaders ) {

			shaderStage.usedTimes --;

			if ( shaderSta