1个canvas互动，3个展示
One canvas to interact, three to display
我正在创建一个浏览器游戏，它可以作为全息图来玩。
屏幕应该显示如下内容：
https://www.youtube.com/watch?v=Y60mfBvXCj8
因此我认为我必须创建 4 个 canvas（没问题），但其中三个应该只显示第一个发生的情况。
我试图让它绘制 canvas 的图像并让它显示给另一个 canvas。
如有任何帮助，我们将不胜感激！
游戏是用Box2D制作的。
编辑：
我希望 space 船在每个 canvas 中绘制，但只控制在一个中。
我的代码：http://s000.tinyupload.com/index.php?file_id=68837773176112789787
问题是，它只显示在一个 canvas!
我在 HTML 中输入的内容：
<canvas id="canvas1" width="500" height="500"></canvas>
<canvas id="canvas2" width="500" height="500"></canvas>
<canvas id="canvas3" width="500" height="500"></canvas>
<canvas id="canvas4" width="500" height="500"></canvas>
打印给其他人的意义：
JS
var sourceCtx, destinationCtx, imageData;
//get the context of each canvas
sourceCtx = canvas2.getContext('2d');
canvas2Ctx = canvas3.getContext('2d');
//copy the data
imageData = sourceCtx.getImageData(0, 0, canvas2.width - 1, canvas2.height - 1);
//apply the image data
canvas3Ctx.putImageData(imageData, 0, 0);
//done
全息金字塔显示器
如何渲染金字塔反射显示器。
为此，请使用 HTML 中的单个显示器 canvas 和存储在内存中的 canvas 用于渲染。
镜像渲染 canvas
渲染 canvas 被剪裁成三角形以防止像素重叠，并且变换被镜像以便正确看到最终效果。例如文本回到前面。
然后将离屏渲染 canvas 渲染到显示器 canvas，从顶部开始，总共制作 4 个副本，每个副本旋转 90 度。
渲染 canvas 宽度将是显示宽度或高度的最小值加上高度的一半以适合显示。
需要全屏模式
要使 FX 正常工作，您需要进入全屏模式。我没有包括这是如何完成的，但我确信在 Whosebug 上有一个 QA 将引导你完成这个过程。
盲区
显示器的中心是金字塔将停留的区域（我称之为死区）由于这些显示器中的许多都是自制的，因此死区的大小会有所不同。在下面的演示的第一行是一个常量 deadZoneSize，它将设置死区大小。当前设置为 0.1，即视图大小的 10%。您可能需要调整此值以适合您的特定反射显示器。
示例代码
代码示例在相关部分充满注释。它将创建和设置显示 canvas 和渲染 canvas。创建剪辑区域并设置镜像渲染变换，以便您可以正常渲染。 mainLoop 函数将调用名为 renderContent 的函数，第一个参数作为渲染的上下文 canvas。只需正常渲染您的内容（使用 size 和 hSize 作为可见渲染区域的宽度和高度（也许我应该使用更好的名称））
该演示包括一个示例渲染，只是为了好玩，它都在底部，并且评论最少，因为与问题无关。
const deadZoneSize = 0.1; // As fraction of fitted box size
// for FX em and em4 are just custom unit size and 1/4 size
var em,em4;
// to fit all four views use the min width or height
var size = Math.min(innerWidth,innerHeight);
// half size
var hSize = size / 2 | 0;
// there is a small area where nothing should be displayed.
// This will depend on the pyrimide being used.
var deadZone = size * 0.1 | 0; // about 10% of view area
// Display canvas d for display
const dCanvas = document.createElement("canvas");
// Render canvas
const rCanvas = document.createElement("canvas");
// get rendering context for both
const dCtx = dCanvas.getContext("2d");
const rCtx = rCanvas.getContext("2d");
// Set the display canvas to fill the page
Object.assign(dCanvas.style,{
position : "absolute",
zIndex : 10, // place above
top : "0px",
left : "0px",
background : "black",
})
// add the display canvas to the DOM
document.body.appendChild(dCanvas);
//Size function resizes canvases when needed
function resize(){
startTime = undefined;
size = Math.min(innerWidth,innerHeight);
hSize = size / 2 | 0;
deadZone = size * deadZoneSize | 0; // about 10% of view area
dCanvas.width = innerWidth;
dCanvas.height = innerHeight;
rCanvas.width = size;
rCanvas.height = hSize; // half height
em = size * 0.1 | 0; // define our own unit size
em4 = Math.max(1,em * 0.25 | 0); // define quarter unit size min of 1
}
// To ensure pixels do not stray outside the view area and overlap use a clip on the render canvas
// ctx the context to appy the clip path to
function defineClip(ctx){
ctx.beginPath();
ctx.lineTo(0,0);
ctx.lineTo(size,0);
ctx.lineTo(hSize + deadZone, hSize - deadZone);
ctx.lineTo(hSize - deadZone, hSize - deadZone);
ctx.clip();
// The rendering is mirrored from the holo pyramid
// to avoid seeing text mirrored you need to mirror the
// rendering transform
ctx.setTransform(-1,0,0,1,size,0); // x axis from right to left, origin at top right
}
// Copying the rendered canvas to the display canvas
// ctx is the display canvas context
// image is the rendered canvas
function display(ctx,image) {
// for each face of the pyramid render a view
// Each image is just rotated 90 deg
// first clear the canvas
ctx.clearRect(0,0,ctx.canvas.width, ctx.canvas.height);
// top
// use the center of the display canvas as the origin
ctx.setTransform(1,0,0,1,ctx.canvas.width / 2 | 0, ctx.canvas.height / 2 | 0);
// draw the image
ctx.drawImage(image,-hSize,-hSize);
// Right
ctx.transform(0,1,-1,0,0,0); // rotate 90 deg. This is better than ctx.rotate as it can have slight
// problems due to floating point errors if not done correctly
ctx.drawImage(image,-hSize,-hSize);
// bottom
ctx.transform(0,1,-1,0,0,0);
ctx.drawImage(image,-hSize,-hSize);
// left
ctx.transform(0,1,-1,0,0,0);
ctx.drawImage(image,-hSize,-hSize);
// restore the default transform;
ctx.setTransform(1,0,0,1,0,0);
}
// the main render loop
var globalTime;
var startTime;
function mainLoop(time){
// check canvas size. If not matching page then resize
if(dCanvas.width !== innerWidth || dCanvas.height !== innerHeight) {
resize();
}
if(startTime === undefined){ startTime = time }
globalTime = time - startTime;
// clear the render canvas ready for next render
rCtx.setTransform(1,0,0,1,0,0); // reset transform
rCtx.globalAlpha = 1; // reset alpha
rCtx.clearRect(0,0,size,hSize);
// save the context state so that the clip can be removed
rCtx.save();
defineClip(rCtx); // set the clip
renderContent(rCtx); // call the rendering function
// restore the context state which removes the clip
rCtx.restore();
// rendering is ready for display so render the holo view
// on to the display canvas's context
display(dCtx, rCanvas);
requestAnimationFrame(mainLoop);
}
requestAnimationFrame(mainLoop);
//=====================================================================================================
// The following is just something interesting to display and is not directly related to the answer
//=====================================================================================================
// The main rendering function
// This is where you render your content. It can be anything from a game to just plain old text
// You can even use a video element and display a video.
// The rendering context is already set up to correctly mirror the content so just render everything as normal
const randG = (min, max , p = 2) => (max + min) / 2 + (Math.pow(Math.random(), p) * (max - min) * 0.5) * (Math.random() < 0.5 ? 1 : -1);
const bootUp = ["Power On",1,1000,"Sub system test",0.5, 3000, "Calibrating scanner",0.5, 6000, "Welcome",1,8000];
function noisyText(ctx){
var textTime = globalTime / 8000; // 8 second boot up
if(screenFlashDone){
if(globalTime > screenFlashes[0]) { // play screen flash seq
screenFlashes.shift();
screenFlash(ctx,true,screenFlashes.shift(),screenFlashes.shift());
}
}else{
screenFlash(ctx);
}
ctx.font = ((bootUp[1] * em) | 0) + "px monospace";
ctx.textAlign = "center";
ctx.textBaseline = "center";
var tx = randG(-em4 * 4, em4 * 4, 64); // G for kind of a bit like gausian. Last num controls distrubution
var ty = randG(-em4 * 4, em4 * 4, 64);
var xx = size / 2 + tx;
var yy = em * 2 + ty;
ctx.fillStyle = `hsl(${randG(160,250,32)|0},100%,50%)`;
if(bootUp[2] < globalTime){
bootUp.shift();
bootUp.shift();
bootUp.shift();
}
ctx.fillText(bootUp[0], xx, yy);
ctx.save(); // need the normal non mirror transform for the noise FX
ctx.setTransform(1,0,0,1,0,0);
for(var y = -em/1.2|0; y < em/2; y += 1){
if((yy+y) % 3 === 0){
ctx.clearRect(0,yy+y,size,1); // give scan line look
}else{
if(Math.random() < 0.1){ // only on 10% of lines.
ctx.drawImage(ctx.canvas,0,yy + y, size, 2,randG(-em4 * 4,em4 * 4,32),yy + y, size, 2);
}
}
}
ctx.fillRect(0,((globalTime / 4000) * hSize)%hSize,size,2);
ctx.filter = `blur(${randG(em4/2,em4,2)|0}px)`;
ctx.drawImage(ctx.canvas,0,0);
ctx.restore();
}
const screenFlashes = [0,500,3,1000,200,2,4000,100,3,6000,100,1,7500,50,1,7800,50,1, 9000];
var screenFlashStart;
var screenFlashLen;
var screenFlashDone = true;
var screenFlashLayers = 1;
function screenFlash(ctx,start,length,layers){
if(start){
screenFlashStart = globalTime;
screenFlashLen = length;
screenFlashDone = false;
screenFlashLayers = layers;
}
var normTime = (globalTime - screenFlashStart) / screenFlashLen;
if(normTime >= 1){
screenFlashDone = true;
normTime = 1;
}
for(var i = 0; i < screenFlashLayers; i++){
var tx = randG(-em4 * 4, em4 * 4, 64); // G for kind of a bit like gausian. Last num controls distrubution
var ty = randG(-em4 * 4, em4 * 4, 64);
ctx.globalAlpha = (1-normTime) * Math.random();
ctx.fillStyle = `hsl(${randG(160,250,32)|0},100%,50%)`;
ctx.fillRect(tx,ty,size,hSize);
}
ctx.globalAlpha = 1;
}
function randomBlur(ctx) {
ctx.save(); // need the normal non mirror transform for the noise FX
ctx.filter = `blur(${randG(em4/2,em4,2)|0}px)`;
ctx.drawImage(ctx.canvas,0,0);
ctx.restore();
}
function ready(ctx) {
ctx.fillStyle = "#0F0";
ctx.font = em + "px monospace";
ctx.textAlign = "center";
ctx.textBaseline = "center";
ctx.fillText("Holographic",hSize,em);
ctx.font = em/2 + "px monospace";
ctx.fillText("display ready.",hSize,em * 2);
// draw edges
ctx.strokeStyle = "#0F0";
ctx.lineWidth = em4;
ctx.beginPath();
ctx.lineTo(0,0);
ctx.lineTo(size,0);
ctx.lineTo(hSize + deadZone, hSize - deadZone);
ctx.lineTo(hSize - deadZone, hSize - deadZone);
ctx.closePath();
ctx.stroke();
}
function renderContent(ctx){
// all rendering is mirrored, but the transform takes care of that for you
// just render as normal. Remember you can only see the
// triangular area with the wide part at the top
// and narrow at the bottom.
// Anything below hSize - deadZone will also not appear
if(globalTime < 8000){
noisyText(ctx);
randomBlur(ctx);
}else{
ready(ctx);
}
randomBlur(ctx);
}
一个简短的旁注。我觉得你的问题符合 SO 要求并且不是题外话，你也不是在找人写代码。你已经表明你在研究上付出了一些努力。这个问题会引起其他人的兴趣。我希望这个答案对您有所帮助，祝您项目顺利，欢迎来到 SO。
我正在创建一个浏览器游戏，它可以作为全息图来玩。 屏幕应该显示如下内容： https://www.youtube.com/watch?v=Y60mfBvXCj8
因此我认为我必须创建 4 个 canvas（没问题），但其中三个应该只显示第一个发生的情况。 我试图让它绘制 canvas 的图像并让它显示给另一个 canvas。
如有任何帮助，我们将不胜感激！
游戏是用Box2D制作的。
编辑：
我希望 space 船在每个 canvas 中绘制，但只控制在一个中。
我的代码：http://s000.tinyupload.com/index.php?file_id=68837773176112789787
问题是，它只显示在一个 canvas!
我在 HTML 中输入的内容：
<canvas id="canvas1" width="500" height="500"></canvas>
<canvas id="canvas2" width="500" height="500"></canvas>
<canvas id="canvas3" width="500" height="500"></canvas>
<canvas id="canvas4" width="500" height="500"></canvas>
打印给其他人的意义：
JS
var sourceCtx, destinationCtx, imageData;
//get the context of each canvas
sourceCtx = canvas2.getContext('2d');
canvas2Ctx = canvas3.getContext('2d');
//copy the data
imageData = sourceCtx.getImageData(0, 0, canvas2.width - 1, canvas2.height - 1);
//apply the image data
canvas3Ctx.putImageData(imageData, 0, 0);
//done
全息金字塔显示器
如何渲染金字塔反射显示器。
为此，请使用 HTML 中的单个显示器 canvas 和存储在内存中的 canvas 用于渲染。
镜像渲染 canvas
渲染 canvas 被剪裁成三角形以防止像素重叠，并且变换被镜像以便正确看到最终效果。例如文本回到前面。
然后将离屏渲染 canvas 渲染到显示器 canvas，从顶部开始，总共制作 4 个副本，每个副本旋转 90 度。
渲染 canvas 宽度将是显示宽度或高度的最小值加上高度的一半以适合显示。
需要全屏模式
要使 FX 正常工作，您需要进入全屏模式。我没有包括这是如何完成的，但我确信在 Whosebug 上有一个 QA 将引导你完成这个过程。
盲区
显示器的中心是金字塔将停留的区域（我称之为死区）由于这些显示器中的许多都是自制的，因此死区的大小会有所不同。在下面的演示的第一行是一个常量 deadZoneSize，它将设置死区大小。当前设置为 0.1，即视图大小的 10%。您可能需要调整此值以适合您的特定反射显示器。
示例代码
代码示例在相关部分充满注释。它将创建和设置显示 canvas 和渲染 canvas。创建剪辑区域并设置镜像渲染变换，以便您可以正常渲染。 mainLoop 函数将调用名为 renderContent 的函数，第一个参数作为渲染的上下文 canvas。只需正常渲染您的内容（使用 size 和 hSize 作为可见渲染区域的宽度和高度（也许我应该使用更好的名称））
该演示包括一个示例渲染，只是为了好玩，它都在底部，并且评论最少，因为与问题无关。
const deadZoneSize = 0.1; // As fraction of fitted box size
// for FX em and em4 are just custom unit size and 1/4 size
var em,em4;
// to fit all four views use the min width or height
var size = Math.min(innerWidth,innerHeight);
// half size
var hSize = size / 2 | 0;
// there is a small area where nothing should be displayed.
// This will depend on the pyrimide being used.
var deadZone = size * 0.1 | 0; // about 10% of view area
// Display canvas d for display
const dCanvas = document.createElement("canvas");
// Render canvas
const rCanvas = document.createElement("canvas");
// get rendering context for both
const dCtx = dCanvas.getContext("2d");
const rCtx = rCanvas.getContext("2d");
// Set the display canvas to fill the page
Object.assign(dCanvas.style,{
position : "absolute",
zIndex : 10, // place above
top : "0px",
left : "0px",
background : "black",
})
// add the display canvas to the DOM
document.body.appendChild(dCanvas);
//Size function resizes canvases when needed
function resize(){
startTime = undefined;
size = Math.min(innerWidth,innerHeight);
hSize = size / 2 | 0;
deadZone = size * deadZoneSize | 0; // about 10% of view area
dCanvas.width = innerWidth;
dCanvas.height = innerHeight;
rCanvas.width = size;
rCanvas.height = hSize; // half height
em = size * 0.1 | 0; // define our own unit size
em4 = Math.max(1,em * 0.25 | 0); // define quarter unit size min of 1
}
// To ensure pixels do not stray outside the view area and overlap use a clip on the render canvas
// ctx the context to appy the clip path to
function defineClip(ctx){
ctx.beginPath();
ctx.lineTo(0,0);
ctx.lineTo(size,0);
ctx.lineTo(hSize + deadZone, hSize - deadZone);
ctx.lineTo(hSize - deadZone, hSize - deadZone);
ctx.clip();
// The rendering is mirrored from the holo pyramid
// to avoid seeing text mirrored you need to mirror the
// rendering transform
ctx.setTransform(-1,0,0,1,size,0); // x axis from right to left, origin at top right
}
// Copying the rendered canvas to the display canvas
// ctx is the display canvas context
// image is the rendered canvas
function display(ctx,image) {
// for each face of the pyramid render a view
// Each image is just rotated 90 deg
// first clear the canvas
ctx.clearRect(0,0,ctx.canvas.width, ctx.canvas.height);
// top
// use the center of the display canvas as the origin
ctx.setTransform(1,0,0,1,ctx.canvas.width / 2 | 0, ctx.canvas.height / 2 | 0);
// draw the image
ctx.drawImage(image,-hSize,-hSize);
// Right
ctx.transform(0,1,-1,0,0,0); // rotate 90 deg. This is better than ctx.rotate as it can have slight
// problems due to floating point errors if not done correctly
ctx.drawImage(image,-hSize,-hSize);
// bottom
ctx.transform(0,1,-1,0,0,0);
ctx.drawImage(image,-hSize,-hSize);
// left
ctx.transform(0,1,-1,0,0,0);
ctx.drawImage(image,-hSize,-hSize);
// restore the default transform;
ctx.setTransform(1,0,0,1,0,0);
}
// the main render loop
var globalTime;
var startTime;
function mainLoop(time){
// check canvas size. If not matching page then resize
if(dCanvas.width !== innerWidth || dCanvas.height !== innerHeight) {
resize();
}
if(startTime === undefined){ startTime = time }
globalTime = time - startTime;
// clear the render canvas ready for next render
rCtx.setTransform(1,0,0,1,0,0); // reset transform
rCtx.globalAlpha = 1; // reset alpha
rCtx.clearRect(0,0,size,hSize);
// save the context state so that the clip can be removed
rCtx.save();
defineClip(rCtx); // set the clip
renderContent(rCtx); // call the rendering function
// restore the context state which removes the clip
rCtx.restore();
// rendering is ready for display so render the holo view
// on to the display canvas's context
display(dCtx, rCanvas);
requestAnimationFrame(mainLoop);
}
requestAnimationFrame(mainLoop);
//=====================================================================================================
// The following is just something interesting to display and is not directly related to the answer
//=====================================================================================================
// The main rendering function
// This is where you render your content. It can be anything from a game to just plain old text
// You can even use a video element and display a video.
// The rendering context is already set up to correctly mirror the content so just render everything as normal
const randG = (min, max , p = 2) => (max + min) / 2 + (Math.pow(Math.random(), p) * (max - min) * 0.5) * (Math.random() < 0.5 ? 1 : -1);
const bootUp = ["Power On",1,1000,"Sub system test",0.5, 3000, "Calibrating scanner",0.5, 6000, "Welcome",1,8000];
function noisyText(ctx){
var textTime = globalTime / 8000; // 8 second boot up
if(screenFlashDone){
if(globalTime > screenFlashes[0]) { // play screen flash seq
screenFlashes.shift();
screenFlash(ctx,true,screenFlashes.shift(),screenFlashes.shift());
}
}else{
screenFlash(ctx);
}
ctx.font = ((bootUp[1] * em) | 0) + "px monospace";
ctx.textAlign = "center";
ctx.textBaseline = "center";
var tx = randG(-em4 * 4, em4 * 4, 64); // G for kind of a bit like gausian. Last num controls distrubution
var ty = randG(-em4 * 4, em4 * 4, 64);
var xx = size / 2 + tx;
var yy = em * 2 + ty;
ctx.fillStyle = `hsl(${randG(160,250,32)|0},100%,50%)`;
if(bootUp[2] < globalTime){
bootUp.shift();
bootUp.shift();
bootUp.shift();
}
ctx.fillText(bootUp[0], xx, yy);
ctx.save(); // need the normal non mirror transform for the noise FX
ctx.setTransform(1,0,0,1,0,0);
for(var y = -em/1.2|0; y < em/2; y += 1){
if((yy+y) % 3 === 0){
ctx.clearRect(0,yy+y,size,1); // give scan line look
}else{
if(Math.random() < 0.1){ // only on 10% of lines.
ctx.drawImage(ctx.canvas,0,yy + y, size, 2,randG(-em4 * 4,em4 * 4,32),yy + y, size, 2);
}
}
}
ctx.fillRect(0,((globalTime / 4000) * hSize)%hSize,size,2);
ctx.filter = `blur(${randG(em4/2,em4,2)|0}px)`;
ctx.drawImage(ctx.canvas,0,0);
ctx.restore();
}
const screenFlashes = [0,500,3,1000,200,2,4000,100,3,6000,100,1,7500,50,1,7800,50,1, 9000];
var screenFlashStart;
var screenFlashLen;
var screenFlashDone = true;
var screenFlashLayers = 1;
function screenFlash(ctx,start,length,layers){
if(start){
screenFlashStart = globalTime;
screenFlashLen = length;
screenFlashDone = false;
screenFlashLayers = layers;
}
var normTime = (globalTime - screenFlashStart) / screenFlashLen;
if(normTime >= 1){
screenFlashDone = true;
normTime = 1;
}
for(var i = 0; i < screenFlashLayers; i++){
var tx = randG(-em4 * 4, em4 * 4, 64); // G for kind of a bit like gausian. Last num controls distrubution
var ty = randG(-em4 * 4, em4 * 4, 64);
ctx.globalAlpha = (1-normTime) * Math.random();
ctx.fillStyle = `hsl(${randG(160,250,32)|0},100%,50%)`;
ctx.fillRect(tx,ty,size,hSize);
}
ctx.globalAlpha = 1;
}
function randomBlur(ctx) {
ctx.save(); // need the normal non mirror transform for the noise FX
ctx.filter = `blur(${randG(em4/2,em4,2)|0}px)`;
ctx.drawImage(ctx.canvas,0,0);
ctx.restore();
}
function ready(ctx) {
ctx.fillStyle = "#0F0";
ctx.font = em + "px monospace";
ctx.textAlign = "center";
ctx.textBaseline = "center";
ctx.fillText("Holographic",hSize,em);
ctx.font = em/2 + "px monospace";
ctx.fillText("display ready.",hSize,em * 2);
// draw edges
ctx.strokeStyle = "#0F0";
ctx.lineWidth = em4;
ctx.beginPath();
ctx.lineTo(0,0);
ctx.lineTo(size,0);
ctx.lineTo(hSize + deadZone, hSize - deadZone);
ctx.lineTo(hSize - deadZone, hSize - deadZone);
ctx.closePath();
ctx.stroke();
}
function renderContent(ctx){
// all rendering is mirrored, but the transform takes care of that for you
// just render as normal. Remember you can only see the
// triangular area with the wide part at the top
// and narrow at the bottom.
// Anything below hSize - deadZone will also not appear
if(globalTime < 8000){
noisyText(ctx);
randomBlur(ctx);
}else{
ready(ctx);
}
randomBlur(ctx);
}
一个简短的旁注。我觉得你的问题符合 SO 要求并且不是题外话，你也不是在找人写代码。你已经表明你在研究上付出了一些努力。这个问题会引起其他人的兴趣。我希望这个答案对您有所帮助，祝您项目顺利，欢迎来到 SO。