我正在尝试编写一个程序,对粒子进行一些基本的重力物理模拟。我最初使用标准的Javascript图形(2d上下文)编写了程序,用这种方法可以获得每秒约25帧/10000个粒子的结果。我改用WebGL重新编写了工具,因为我认为那样可以获得更好的结果。我还使用了glMatrix库进行向量数学计算。然而,通过这种实现方式,我只能在10000个粒子下获得大约15帧。
我目前是一名EECS本科生,有相当多的编程经验,但从未涉及过图形,并且我很少了解如何优化Javascript代码。关于使用这些技术时影响性能的关键组件有哪些?是否有更有效的数据结构来管理我的粒子(我只是使用了一个简单的数组)?使用WebGL导致性能下降的原因可能是什么?GPU和Javascript之间的延迟是不是其中之一?
任何建议、解释或一般性的帮助将不胜感激。
以下是我参考的关键代码区域:
这是我的设置代码:
gl = null;
try {
// Try to grab the standard context. If it fails, fallback to experimental.
gl = canvas.getContext("webgl") || canvas.getContext("experimental-webgl");
gl.viewportWidth = canvas.width;
gl.viewportHeight = canvas.height;
}
catch(e) {}
if(gl){
gl.clearColor(0.0,0.0,0.0,1.0);
gl.clearDepth(1.0); // Clear everything
gl.enable(gl.DEPTH_TEST); // Enable depth testing
gl.depthFunc(gl.LEQUAL); // Near things obscure far things
// Initialize the shaders; this is where all the lighting for the
// vertices and so forth is established.
initShaders();
// Here's where we call the routine that builds all the objects
// we'll be drawing.
initBuffers();
}else{
alert("WebGL unable to initialize");
}
/* Initialize actors */
for(var i=0;i<NUM_SQS;i++){
sqs.push(new Square(canvas.width*Math.random(),canvas.height*Math.random(),1,1));
}
/* Begin animation loop by referencing the drawFrame() method */
gl.bindBuffer(gl.ARRAY_BUFFER, squareVerticesBuffer);
gl.vertexAttribPointer(vertexPositionAttribute, 2, gl.FLOAT, false, 0, 0);
requestAnimationFrame(drawFrame,canvas);
绘画循环:
function drawFrame(){
// Clear the canvas before we start drawing on it.
gl.clear(gl.COLOR_BUFFER_BIT);
//mvTranslate([-0.0,0.0,-6.0]);
for(var i=0;i<NUM_SQS;i++){
sqs[i].accelerate();
/* Translate current buffer (?) */
gl.uniform2fv(translationLocation,sqs[i].posVec);
/* Draw current buffer (?) */;
gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
}
window.requestAnimationFrame(drawFrame, canvas);
}
这是Square继承的类:
function PhysicsObject(startX,startY,size,mass){
/* Class instances */
this.posVec = vec2.fromValues(startX,startY);
this.velVec = vec2.fromValues(0.0,0.0);
this.accelVec = vec2.fromValues(0.0,0.0);
this.mass = mass;
this.size = size;
this.accelerate = function(){
var r2 = vec2.sqrDist(GRAV_VEC,this.posVec)+EARTH_RADIUS;
var dirVec = vec2.create();
vec2.set(this.accelVec,
G_CONST_X/r2,
G_CONST_Y/r2
);
/* Make dirVec unit vector in direction of gravitational acceleration */
vec2.sub(dirVec,GRAV_VEC,this.posVec)
vec2.normalize(dirVec,dirVec)
/* Point acceleration vector in direction of dirVec */
vec2.multiply(this.accelVec,this.accelVec,dirVec);//vec2.fromValues(canvas.width*.5-this.posVec[0],canvas.height *.5-this.posVec[1])));
vec2.add(this.velVec,this.velVec,this.accelVec);
vec2.add(this.posVec,this.posVec,this.velVec);
};
}
这些是我正在使用的着色器:
<script id="shader-fs" type="x-shader/x-fragment">
void main(void) {
gl_FragColor = vec4(0.7, 0.8, 1.0, 1.0);
}
</script>
<!-- Vertex shader program -->
<script id="shader-vs" type="x-shader/x-vertex">
attribute vec2 a_position;
uniform vec2 u_resolution;
uniform vec2 u_translation;
void main() {
// Add in the translation.
vec2 position = a_position + u_translation;
// convert the rectangle from pixels to 0.0 to 1.0
vec2 zeroToOne = position / u_resolution;
// convert from 0->1 to 0->2
vec2 zeroToTwo = zeroToOne * 2.0;
// convert from 0->2 to -1->+1 (clipspace)
vec2 clipSpace = zeroToTwo - 1.0;
gl_Position = vec4(clipSpace*vec2(1,-1), 0, 1);
}
</script>
我为此冗长的表述道歉。再次,任何建议或朝正确方向的推动都将是巨大的帮助。