我的目标是创建一个有效的游戏循环，使用requestAnimationFrame更新显示画布，setTimeout更新游戏逻辑。我的问题是我应该将所有绘图操作放在requestAnimationFrame循环中还是只放置更新html画布的主绘图操作？
我的意思是＆＃34;所有的绘图操作＆＃34;是所有的缓冲。例如，我将所有精灵绘制到缓冲区，然后将缓冲区绘制到主画布上。一方面，如果我将所有缓冲放入requestAnimationFrame我不会在每次逻辑更新上浪费cpu绘图，另一方面，绘图是cpu很重并且可能导致requestAniomationFrame等到所有这些操作都完成了......将逻辑更新与绘图分开是为了让requestAnimationFrame不会因非绘图处理而陷入困境。
有没有人有这种方法来创建游戏循环的经验？并且不要说＆＃34;只需将其全部放在requestAnimationFrame，＆＃34;因为这会减慢渲染速度。我确信将逻辑与绘图分离是可行的方法。以下是我所谈论的一个例子：
/* The drawing loop. */
function render(time_stamp_){//First parameter of RAF callback is timestamp.
window.requestAnimationFrame(render);
/* Draw all my sprites in the render function? */
/* Or should I move this to the logic loop? */
for (var i=sprites.length-1;i>-1;i--){
sprites[i].drawTo(buffer);
}
/* Update the on screen canvas. */
display.drawImage(buffer.canvas,0,0,100,100,0,0,100,100);
}
/* The logic loop. */
function update(){
window.setTimeout(update,20);
/* Update all my sprites. */
for (var i=sprites.length-1;i>-1;i--){
sprites[i].update();
}
}
谢谢！
编辑：
我决定与网络工作者一起将游戏逻辑与绘图完全分开，根据我的理解，这必须在DOM加载的主脚本中进行。
答案 0 :(得分：2)
所以，我从来没有找到一种分离逻辑和绘图的好方法，因为JavaScript使用单个线程。无论我做什么，绘制函数的执行都可能妨碍逻辑，反之亦然。我所做的是找到一种方法以尽可能最及时的方式执行它们，同时确保使用requestAnimation Frame对逻辑和优化绘图进行持续的时间更新。如果设备太慢而无法以所需的帧速率绘制，则该系统被设置为插入动画以弥补跳过的帧。无论如何，这是我的代码。
var engine = {
/* FUNCTIONS. */
/* Starts the engine. */
/* interval_ is the number of milliseconds to wait between updating the logic. */
start : function(interval_) {
/* The accumulated_time is how much time has passed between the last logic update and the most recent call to render. */
var accumulated_time = interval_;
/* The current time is the current time of the most recent call to render. */
var current_time = undefined;
/* The amount of time between the second most recent call to render and the most recent call to render. */
var elapsed_time = undefined;
/* You need a reference to this in order to keep track of timeout and requestAnimationFrame ids inside the loop. */
var handle = this;
/* The last time render was called, as in the time that the second most recent call to render was made. */
var last_time = Date.now();
/* Here are the functions to be looped. */
/* They loop by setting up callbacks to themselves inside their own execution, thus creating a string of endless callbacks unless intentionally stopped. */
/* Each function is defined and called immediately using those fancy parenthesis. This keeps the functions totally private. Any scope above them won't know they exist! */
/* You want to call the logic function first so the drawing function will have something to work with. */
(function logic() {
/* Set up the next callback to logic to perpetuate the loop! */
handle.timeout = window.setTimeout(logic, interval_);
/* This is all pretty much just used to add onto the accumulated time since the last update. */
current_time = Date.now();
/* Really, I don't even need an elapsed time variable. I could just add the computation right onto accumulated time and save some allocation. */
elapsed_time = current_time - last_time;
last_time = current_time;
accumulated_time += elapsed_time;
/* Now you want to update once for every time interval_ can fit into accumulated_time. */
while (accumulated_time >= interval_) {
/* Update the logic!!!!!!!!!!!!!!!! */
red_square.update();
accumulated_time -= interval_;
}
})();
/* The reason for keeping the logic and drawing loops separate even though they're executing in the same thread asynchronously is because of the nature of timer based updates in an asynchronously updating environment. */
/* You don't want to waste any time when it comes to updating; any "naps" taken by the processor should be at the very end of a cycle after everything has already been processed. */
/* So, say your logic is wrapped in your RAF loop: it's only going to run whenever RAF says it's ready to draw. */
/* If you want your logic to run as consistently as possible on a set interval, it's best to keep it separate, because even if it has to wait for the RAF or input events to be processed, it still might naturally happen before or after those events, and we don't want to force it to occur at an earlier or later time if we don't have to. */
/* Ultimately, keeping these separate will allow them to execute in a more efficient manner rather than waiting when they don't have to. */
/* And since logic is way faster to update than drawing, drawing won't have to wait that long for updates to finish, should they happen before RAF. */
/* time_stamp_ is an argument accepted by the callback function of RAF. It records a high resolution time stamp of when the function was first executed. */
(function render(time_stamp_) {
/* Set up the next callback to RAF to perpetuate the loop! */
handle.animation_frame = window.requestAnimationFrame(render);
/* You don't want to render if your accumulated time is greater than interval_. */
/* This is dropping a frame when your refresh rate is faster than your logic can update. */
/* But it's dropped for a good reason. If interval > accumulated_time, then no new updates have occurred recently, so you'd just be redrawing the same old scene, anyway. */
if (accumulated_time < interval_) {
buffer.clearRect(0, 0, buffer.canvas.width, buffer.canvas.height);
/* accumulated_time/interval_ is the time step. */
/* It should always be less than 1. */
red_square.draw(accumulated_time / interval_);
html.output.innerHTML = "Number of warps: " + red_square.number_of_warps;
/* Always do this last. */
/* This updates the actual display canvas. */
display.clearRect(0, 0, display.canvas.width, display.canvas.height);
display.drawImage(buffer.canvas, 0, 0, buffer.canvas.width, buffer.canvas.height, 0, 0, display.canvas.width, display.canvas.height);
}
})();
},
/* Stops the engine by killing the timeout and the RAF. */
stop : function() {
window.cancelAnimationFrame(this.animation_frame);
window.clearTimeout(this.timeout);
this.animation_frame = this.timeout = undefined;
},
/* VARIABLES. */
animation_frame : undefined,
timeout : undefined
};
这是从我的一个项目中直接撕掉的，所以在那里有一些变量在代码的其他地方定义。 red_square是其中一个变量。如果您想查看完整示例，请查看我的github页面！ userpoth.github.io另外，旁注，我尝试使用网络工作者来分离逻辑，这是一个悲惨的失败。当你有很多数学要做的事情并且很少有对象在线程之间传递时，网络工作者是很棒的，但他们不能进行绘图，而且他们在大数据传输方面很慢，至少在游戏逻辑的上下文中。
答案 1 :(得分：1)
据我了解你的问题，关键点是
在您的代码中，您决定每秒执行此操作20次。
在这种情况下，我会设置一个时间戳，指示此操作何时完成。
在requestAnimationFrame代码中，测试此时间戳是否已超过1/20秒，然后执行代码。