three.js/src/renderers/webgl/WebGLBufferRenderer.js

function WebGLBufferRenderer( gl, extensions, info ) {

	let mode;

	function setMode( value ) {

		mode = value;

	}

	function render( start, count ) {

		gl.drawArrays( mode, start, count );

		info.update( count, mode, 1 );

	}

	function renderInstances( start, count, primcount ) {

		if ( primcount === 0 ) return;

		gl.drawArraysInstanced( mode, start, count, primcount );

		info.update( count, mode, primcount );

	}

	function renderMultiDraw( starts, counts, drawCount ) {

		if ( drawCount === 0 ) return;

		const extension = extensions.get( 'WEBGL_multi_draw' );

		if ( extension === null ) {

			for ( let i = 0; i < drawCount; i ++ ) {

				this.render( starts[ i ], counts[ i ] );

			}

		} else {

			extension.multiDrawArraysWEBGL( mode, starts, 0, counts, 0, drawCount );

			let elementCount = 0;
			for ( let i = 0; i < drawCount; i ++ ) {

				elementCount += counts[ i ];

			}

			info.update( elementCount, mode, 1 );

		}

	}

	function renderMultiDrawInstances( starts, counts, drawCount, primcount ) {

		if ( drawCount === 0 ) return;

		const extension = extensions.get( 'WEBGL_multi_draw' );

		if ( extension === null ) {

			for ( let i = 0; i < starts.length; i ++ ) {

				renderInstances( starts[ i ], counts[ i ], primcount[ i ] );

			}

		} else {

			extension.multiDrawArraysInstancedWEBGL( mode, starts, 0, counts, 0, primcount, 0, drawCount );

			let elementCount = 0;
			for ( let i = 0; i < drawCount; i ++ ) {

				elementCount += counts[ i ];

			}

			for ( let i = 0; i < primcount.length; i ++ ) {

				info.update( elementCount, mode, primcount[ i ] );

			}

		}

	}

	//

	this.setMode = setMode;
	this.render = render;
	this.renderInstances = renderInstances;
	this.renderMultiDraw = renderMultiDraw;
	this.renderMultiDrawInstances = renderMultiDrawInstances;

}


export { WebGLBufferRenderer };