根据透视相机参数计算投影矩阵

makePerspective( left, right, top, bottom, near, far ) {

		const te = this.elements;
		const x = 2 * near / ( right - left );
		const y = 2 * near / ( top - bottom );

		const a = ( right + left ) / ( right - left );
		const b = ( top + bottom ) / ( top - bottom );
		const c = - ( far + near ) / ( far - near );
		const d = - 2 * far * near / ( far - near );

		te[ 0 ] = x;	te[ 4 ] = 0;	te[ 8 ] = a;	te[ 12 ] = 0;
		te[ 1 ] = 0;	te[ 5 ] = y;	te[ 9 ] = b;	te[ 13 ] = 0;
		te[ 2 ] = 0;	te[ 6 ] = 0;	te[ 10 ] = c;	te[ 14 ] = d;
		te[ 3 ] = 0;	te[ 7 ] = 0;	te[ 11 ] = - 1;	te[ 15 ] = 0;

		return this;

	}