WebGL自由研究「scissorで3D」。raw WebGL 3d sample without WebGLProgram.

scissor3d.html

<canvas width="512" height="512"></canvas>
<script>"use strict";
let opt={preserveDrawingBuffer:true}
let cx=document.querySelector("canvas").getContext("webgl",opt);
function draw(now){
	let x,y,z, sec=now/1000;
	cx.disable(cx.SCISSOR_TEST);
	cx.clearColor(0,0,.6,1);	cx.clear(0x4000);
	cx.enable(cx.SCISSOR_TEST);
	for(let i=0;i<100000; i++){
		x=Math.random()*2-1;
		y=Math.random()*2-1;
		z=Math.random()*2-1;
		if(Math.abs(x)<0.5 && Math.abs(y)<0.2 && Math.abs(z)<0.5){
			[x,z]=rot(x,z,sec);
			[y,z]=rot(y,z,sec/2);
			[x,y,z]=prs(x, y, z, .5);
			cx.scissor(x*256+256,y*256+256,2,2);
			cx.clearColor(1,1,0,1);	cx.clear(0x4000);
		}
	}
	requestAnimationFrame(draw);
};	requestAnimationFrame(draw);
function rot(x,y,th){let c=Math.cos(th),s=Math.sin(th);return [x*c-y*s,x*s+y*c]}
function prs(x,y,z,f){let w=1+(z*f);return [x/w, y/w, z/w]}
</script>