Webgl readpixels slow. var lastMouseX = null .

Webgl readpixels slow. readPixels in pure WEBGL). Mar 15, 2022 · [SOLVED] WebGL issue on Chrome and Firefox, Linux Mint 20, AMD Radeon by annielm » Tue Mar 15, 2022 11:18 pm Mar 21, 2021 · First time posting on the forums ^-^ I’m making a game where there are millions of instanced meshes with their positions being controlled by what’s effectively a compute shader Link if anyone’s interested in how that’s been set up The issue I’m having is that texture. If you use pure webgl, everything is draw inside this "context-3d" of a canvas. Jan 22, 2023 · Second round - WebGL readPixels() → pass raw pixels data directly into the encoder In my 2nd attempt, I created an open ReadableStream while exporting the video and connected to the encoder, reading those pixels “live” and encoding them ad-hoc. drawImage + context2d glReadPixels(0, 0, w[index], h[index], GL_DEPTH_COMPONENT, GL_FLOAT, 0); Performance issues of this nature are typically caused by the OpenGL driver needing to do a format conversion during the read or write operation. That works fine but wouldn't it be better if I could directly access the pixels in the WebGLTextureObject? Jun 9, 2021 · The second run (with 16 threads and 30GB RAM, using flat-nodes, which should slow things) took ~39 hours. Webgl hits the slow path for gl Read Pixels with LLVMpipe 在上面的示例中，我们首先创建了一个渲染缓冲 renderBuffer，并将其绑定到帧缓冲 frameBuffer 的颜色附件上。然后，我们在帧缓冲上进行渲染，可以是绘制3D场景或者其他图形。最后，我们使用 readPixels 函数将渲染结果读取到 pixelData 数组中。 处理像素数据 一旦我们将像素数据读取到数组中，就可以对 Jun 22, 2022 · My first step is to take screenshots of areas using WebGL that I may use to analyze parts of the UI. 6ms on nvidia) Jul 31, 2024 · WebGL (Web Graphics Library) is a powerful JavaScript API used to render 3D and 2D graphics within any compatible web browser. I also get this warning in the devtools console: [. Here is a part of my code (context initialization, mouseDown event function). readRenderTargetPixels( renderTarget, x, y, 1, 1 Mar 22, 2019 · 0. For that I'm using WebGLRenderingContext#readPixels. I have used : render_list -m default -a -z 0 -Z 15 --num-threads=20 I feel that this process is extremely slow. renderer. domElement. Nov 2, 2021 · Now, I feel that de facto rendering of tiles is extremely slow for production environments when i cross zoom level 5-6. Is this approach reasonable? Does anyone have a sample code for this? The WebGLRenderingContext. Unfortunately, I didn't create the create volume ("docker volume create openstreetmap-data") this time, so I will likely need to do one more import (had planned to anyway, for testing purposes). why readPixels so slow in webGL? anyone knows how to solve this problem? Jan 13, 2015 · I am implementing GLSL picking, which relies on readPixels() to get single pixel data. In a first time, before trying ray tracing, I’m trying to use the alpha channel (I only have a few items in my scene) to select the item corresponding to the cursor. Apr 27, 2022 · The P2VR7 script feels slower and more laggy, than the P2VR6 one. Use headless-shell as the base image (Server) and deploy the same codebase to the server (K8S Cluster , 1C/4G for one pod setup) , the iframe-based render process becomes slow and print the log : 8. But glReadPixels () is slow and takes most of my app time. However, achieving optimal performance with WebGL requires careful attention to various aspects of your code and rendering pipeline. test_sdl_gl_mapbuffers currently fails with: test. 3K subscribers in the webgl community. I suppose I'll try and find a better more efficient way. Otherwise my collision detection would be gone. T Jan 8, 2018 · Hello ! the method using canvas. 我正在尝试使用WebGL来加速小型量子电路模拟中的计算，类似于Quantum Computing Playground。 我遇到的问题是readPixels需要大约10毫秒，但我想在动画期间每帧调用它Working around WebGL readPixels being slow Aug 22, 2022 · Hello, I want to read pixels in each frame and the original API readPixels is very slow. var lastMouseX = null Mar 4, 2013 · WebGL data transfer to/from GPU is slower than firefox (texImage2D and readPixels) Bug P3 Add Hotlist Available Status Update No update yet. js (which I assume it will be the same as gl. Mar 30, 2021 · Use extract in pixi to get data when you update the renderTexture, i hope its not often :) extract uses webgl readPixels operation. engine. getElementById("canvas"); const ctx = canvas. getHeight(), GL20. Creation of the WebGPU engine is asynchronous Creating the engine is also asynchronous in WebGPU. For example . getImageData() after rendering to Canvas. readPixels。 然后我的问题是:如何使用gl. Jan 12, 2021 · Web worker version of human probably doesn't work on Firefox because OffscreenCanvas is required, which is still a behind-a-flag feature on Firefox. Which is why it acts so slow, but also why we have guarantees that every readPixels call is gonna return data from the framebuffer in that specific moment in time. readPixels (10, 35, 1, 1, ); I'm sure you thought gl. getContext("webgl2"); Feb 2, 2015 · 我试图用WebGL来加速模拟一个小量子电路的计算速度，比如。我遇到的问题是，readPixels占用10 is，但是我想在动画时每帧调用它几次，以便从gpu-land和javascript-land获取信息。举个例子，这是我的确切用例。下面的电路动画是通过计算每一列门之间的状态来创建的，目的是显示内联线上的存在概率图： Apr 4, 2017 · 0 Has anyone used xtk with webgl2 to do the pick () call? specifically renderer3d's. gl — a 3D map of the world built using WebGL2 Mar 21, 2021 · First time posting on the forums ^-^ I’m making a game where there are millions of instanced meshes with their positions being controlled by what’s effectively a compute shader Link if anyone’s interested in how that’s been set up The issue I’m having is that texture. Aug 6, 2014 · On Windows I still find WebGL slow even without debugging enabled. The only other thing that comes to mind for the remaining difference in speed is how the browsers transfer the canvas to texture. It tends to be slow especially on mobile devices. In order to enter VR on Sep 2, 2022 · What did you do? Include clear steps. WebGLDriverTest] A problem was detected with your graphics driver. readPixels () documentation: Parameters x Oct 3, 2016 · Why is glReadPixels so slow and are there any alternative? Asked 9 years ago Modified 9 years ago Viewed 10k times reading the results from WebGL is slow so it's important to avoid it as much as possible. readRenderTargetPixels () internally uses gl. GL_UNSIGNED_BYTE, pixels); The problem is that it blocks the rendering and is slow. readRenderTargetPixels() in Three. js:1445:5 Aug 11, 2023 · Refer to this thread’s answer. So I force Canvas rendering in this instance. I was bombarding this stream with billions of RGBA, RGBA, RGBA values. I'm running a well updated Ubuntu 20. Jan 7, 2018 · 这两种方法工作并给出相同的结果，但第二种方法几乎比使用context2d. getWidth(), Gdx. 3. readPixels Returns 8 bit or integer RGBA values In general, the format of pixels in the frame buffer is different from that of processor memory and these two types of memory reside in different places Need packing and unpacking Reading can be slow Feb 1, 2017 · Why is the imageData that I get from WebGLRenderingContext. 04 on my XPS15 9550. Dec 16, 2024 · Warnings in the console are: GPU stall due to ReadPixels CONTEXT_LOST_WEBGL Uncaught (in promise) 'AbortError' I've been working with IT trying to resolve the issue but its been difficult. Learn more Sep 30, 2015 · Apparently readPixels is slow and from Darth Melkor on GameDev "The number of pixels you read doesnt matter as much as the stall, which you'll still get even with a 1x1 region and on the fastest modern hardware - better to use a method that doesnt involve reading back". Mar 4, 2021 · Safari, Chrome, and Firefox all have their own APIs that go from WebGL -> GPU driver instructions, so it's often the case that you'll see different behavior or different platforms due to either (1) bugs in the browser or (2) browser-specific workarounds for bugs in graphics drivers. My first attempt was to simply draw color map (1x1 pixel) on the screen, read the pixel, then draw over it. I find some similar questions like this and this. Depending how the driver implements this format conversion, this could sometimes be as bad as needing to block all pending operations, copy the buffer off to CPU-side scratch As a followup from a previous post, I have been trying to track down some slowdown I am having when drawing a scene using Javascript and the canvas element. Speeding those things up is on our roadmap. Any issue added here will be closed as a duplicate of this one, making this the "canonical issue". The DrawCall that makes the shaders execute looks quite fast to me (glDrawArrays in the image), but glReadPixels (I read the image to retrieve the results) is really slow. I think most of the time this is a win for Chrome WebGL performance over Firefox WebGL performance but not always. Now it's really bad. Nov 29, 2012 · How do I get pixels of that texture (similar to WebGL's readPixels, but for a texture)? One idea I have is to create a canvas and a WebGL context with preserveDrawingBuffer=true, and render my texture on this canvas so that it shows 2D flat, and then use readPixels. From the spec: For normalized fixed-point rendering surfaces, the combination format RGBA and type UNSIGNED_BYTE is accepted. getImageData的方法慢2倍。 对我来说听起来很奇怪。将3D素材绘制到2D-canvas中会比直接使用context3D更快吗？我不明白，我几乎可以肯定我没有正确使用gl. readPixels () which is a synchronous operation. webgl I'm trying to use WebGL to speed up computations in a simulation of a small quantum circuit, like what the Quantum Computing Playground does. Mar 15, 2022 · [SOLVED] WebGL issue on Chrome and Firefox, Linux Mint 20, AMD Radeon by annielm » Tue Mar 15, 2022 11:18 pm Aug 21, 2018 · Working around WebGL readPixels being slow optimization, webgl asked by Craig Gidney on 05:07PM - 02 Feb 15 UTC pailhead August 22, 2018, 3:24am 5 Jun 12, 2021 · The problem is that WebGLRenderer. 0 section 4. views. So I would also expect to see differences there when it comes to WebGL-related browser/driver-specific issues. readPixels directly to ArrayBuffer - note CPU is pegged throughout. Depending how the driver implements this format conversion, this could sometimes be as bad as needing to block all pending operations, copy the buffer off to CPU-side scratch Free screencast video tutorials about WebGL for programmers and developers who like to learn. We know readpixels limitations and synchronization issue it occurs, but I fail to make sense of 40ms for a "readpixels" on intel GPU , even on Nvidia GTX 1070, 3ms for a readpixels seems enormous In both case readpixels takes the time of at least 3 gpu render (10ms on intel gpu, 0. The WebGLRenderingContext. Here is a sample output : Buffer Reading WebGL can read pixels from the current framebuffer with gl. js:1977:7 Error: WebGL: readPixels: Out-of-bounds reads with readPixels are deprecated, and may be slow. Nov 30, 2018 · I have a giant shader that takes more than a minute to compile, which completely stalls whole browser during the process. js:4697 WebGL: INVALID_VALUE: readPixels: destination offset out of range Jan 16, 2015 · Do you have a jsfiddle or something similar that you can link to with the code that is causing you problems? It would be easier to help with it Mar 4, 2021 · Safari, Chrome, and Firefox all have their own APIs that go from WebGL -> GPU driver instructions, so it's often the case that you'll see different behavior or different platforms due to either (1) bugs in the browser or (2) browser-specific workarounds for bugs in graphics drivers. More info See in Glossary graphics API uses your GPU for hardware WebGL: INVALID_ENUM: readPixels: invalid format Is it possible to make gl_FragColor to output 1 byte per pixel in LUMINANCE mode, instead of RGBA, but the input texture has to be RGBA? If the format of gl rendering cannot be changed, is it possible to read only the first byte of each 4 bytes pixel, when calling gl. As an example nether the particle system above nor the dynamic closest lines example ever read the results back to JavaScript. But these two questions seem have no good approach to read pixels from texture… Jun 16, 2012 · in chrome, WebGL readPixels (only read one pixel) needs about 10ms, in firefox, it needs about 5ms, in opera, it needs about 3ms. 7毫秒(全部为10毫秒)，读取像素的速度也非常慢。 我在一个运行于webgl的datavis平台上工作，但令我困惑的是为什么readpixels如此之慢。我们正在使用颜色拾取的方法来测试一个被拖动的项目，这样它就可以被拖到物体上 Mar 4, 2021 · It would appear that the issue is with Esri's WebGl engine and it not working with the machine's graphics driver as evidenced by the following console warning on Chrome based browsers: [esri. I decided to narrow down my focus to a WebGLRenderingContext. WebGL2 readPixels In WebGL you pass a format/type pair to readPixels. During the slow readPixels you can see loads of syscalls going on, looks like repeated calls to IOSurfaceClientLock and IOSurfaceClientUnlock. The problem I'm running into is that readPixels takes ~10ms, but I want to call it several times per frame while animating in order to get information out of gpu-land and into javascript-land. Jul 22, 2020 · Hi, I’m building a robotics simulator, and am using an RTT camera to simulate a color sensor. Syntax // WebGL1: void gl. readPixels starts reading pixels from the top left corner, but it doesn't. readRenderTargetPixels( renderTarget, x, y, 1, 1 Free screencast video tutorials about WebGL for programmers and developers who like to learn. Error: WebGL: drawArrays: Feedback loop detectedrenderer3D. I can extract the pixel data using readRenderTargetPixels with the default renderer I’ve set up. (BTW, you need to click "Run" below the canvas every time you modify the source code or flip between ANGLE and native GL, otherwise the changes won't take effect. readPixels() 方法从当前的颜色帧缓冲（framebuffer）中读取指定矩形的像素矩阵并转换为 TypedArray 或 DataView 对象。 Jul 18, 2022 · MapViewer Classic does not always use WebGL, and when it does, it's a very early version of the 4x engine. readPixels (x, y, width, height, format, type, GLintptr offset); void gl Apr 27, 2022 · The P2VR7 script feels slower and more laggy, than the P2VR6 one. readPixels () The WebGLRenderingContext. getImageData with webgl have been optimised in chrome between the day I wrote this post and now because it's now possible to check the pixels of canvas containing a webgl-movie at 60fps even with a big resolution. /test/runner browser64_4gb. Aug 10, 2023 · 在无头浏览器打开网页，使用到Mapbox-gl-js 地图底图 和 L7 的lineLayer图层，导致服务器报错 [. 背景介绍 前段时间用WebGL做整车的web端展示，发现当三角片数量大于一定量级后，在微信内置浏览器内打开模型时，浏览器直接崩溃。于是就想到了数据压缩，花了大概一周多时 In general, Web performance is close to native apps on the GPU, because the WebGL A JavaScript API that renders 2D and 3D graphics in a web browser. So it seems that readPixels is particularly slow on ANGLE. WebGL-0x322800306200]GL Driver Message (OpenGL, Performance, GL_CLOSE_PATH_NV, High): GPU stall due to ReadPixels', 'source': 'rendering' Feb 25, 2013 · At the moment I'm using gl. readPixels() method of the WebGL API reads a block of pixels from a specified rectangle of the current color framebuffer into an ArrayBufferView object. In WebGL you pass a format/type pair to readPixels. This page tackles recommendations across the spectrum of expertise, and not only highlights dos and don'ts, but also details why. You don't have to enter VR to see the huge delay. These were both full-planet imports. It used to work prior to a system outage and then stopped working once the systems were back up an running. andreas Note: This code should run on opengl and opengles. From the WebGLRenderingContext. The Official Khronos WebGL Repository. The Unity Web build option allows Unity to publish content as JavaScript programs which use HTML5 technologies and the WebGL rendering API to run Unity content in a web browser. I have heard of Pixel Buffer Objects, but I am quite unsure on how to wire it up and whether it is faster or not. From this MDN article (WebGL Nov 2, 2021 · In WebGL 1, this blocks the main thread and guarantees that every call is gonna always be executed in the same animation frame that it was called. Also is there any other Feb 2, 2015 · 我试图用WebGL来加速模拟一个小量子电路的计算速度，比如。我遇到的问题是，readPixels占用10 is，但是我想在动画时每帧调用它几次，以便从gpu-land和javascript-land获取信息。举个例子，这是我的确切用例。下面的电路动画是通过计算每一列门之间的状态来创建的，目的是显示内联线上的存在概率图： Apr 4, 2017 · 0 Has anyone used xtk with webgl2 to do the pick () call? specifically renderer3d's. getContext("webgl2"); Is there a way to increase the speed of glReadPixels? Currently I do: Gdx. I'll give Pixel Buffer Objects a try. 2d. According to the spec, only 2 formats are allowed for readPixels OpenGL ES 3. readPixels() upside down? I try to do the folowing: var gl = renderer. 在 WebGL 中，你给 readPixels 传格式/类型。 对于给定的纹理内部格式（附加在帧缓冲器上），只有 2 种有效的格式/类型组合。 Dec 1, 2018 · There appears to be bugs in both firefox and chrome with readPixels but the spec is sadly ambiguous here. As the pixel data is being used to control the simulated robot movement, there’s no option for me to keep the data in GPU; it must be brought into main memory. As Jun 8, 2017 · The WebGLRenderingContext. This issue has no duplicates A duplicate is an issue with similar content. graphics. . JSFiddle has a BUG and it doesn't show the VRButton on mobile. Your driver does not appear to honor sampler precision specifiers, which may result in rendering issues due to 0 I have two shapes rendered along with different texture mapped on each. For a given texture internal format (attached to a framebuffer), only 2 combinations of format/type are valid. Jun 30, 2022 · WebGL performance issue -> "GPU stall due to ReadPixels" Full message: [. If you want to implement any form of interaction, traditional raycasting is much faster. As far as I know shader compilation cannot be made asynchronous, so you can Jan 7, 2018 · 这两种方法工作并给出相同的结果，但第二种方法几乎比使用context2d. readPixels is really slow, I found an async alternative for reading pixels in the source code for the default engine Jan 8, 2022 · 3. This is done after a stencil test I use for 2D collision detection. js:4697 WebGL: INVALID_VALUE: readPixels: destination offset out of range Jan 16, 2015 · Do you have a jsfiddle or something similar that you can link to with the code that is causing you problems? It would be easier to help with it NEW (nobody) in Core - Graphics: CanvasWebGL. ReadPixels to read the pixels after I've drawn the texture to my framebuffer. Apr 4, 2012 · Hello, I’m trying to do picking with openGL. readpixels UPDATE: Notes / how to use: This demo runs both in normal mode, and in WebXR mode. However, readPixels is a slow operation that should be done in the end of frame, that's why renderTexture's are not suited for hit detection. Feb 25, 2024 · 我正在尝试使用 WebGL 来加速小型量子电路模拟中的计算，就像 Quantum Computing Playground does 那样。 。我遇到的问题是 readPixels 需要大约 10ms，但我 Mar 22, 2021 · TLDR; WebGL running smooth Win10 & previous Ubuntu 18. gl. getContext("webgl") var pixels = new Uint8Array(gl. readPixels (x, y, width, height, format, type, pixels); // WebGL2: void gl. Contribute to KhronosGroup/WebGL development by creating an account on GitHub. Jun 10, 2025 · WebGL is a complicated API, and it's often not obvious what the recommended ways to use it are. ) Jul 11, 2020 · Of course the fact that Chrome is running the commands in another process means you get some parallel processing for free. Feb 28, 2024 · Emscripten tests that rely on readPixels are currently failing in 4gb high memory mode (where all pointers are greater than 2^32. glReadPixels(0, 0, Gdx. WebGL-000060C4089B8700]GL Driver Message (OpenGL, Performance, GL_CLOSE_PATH_NV, High): GPU stall due to ReadPixels from what I know, you should avoid ReadPixels as much as possible and combine ReadPixels requests as it's a GPU Blocking request. readPixels starts reading them from the lower left corner. streets. WebGLRenderingContext. Since I updated from Ubuntu 18 I recognized WebGL or other WebGL API 的 WebGLRenderingContext. readPixels来比context2d. Here's a snippet reading the whole canvas and saving its' pixels as RGBA: const canvas = document. Jan 7, 2019 · 当尝试对大量数据(但屏幕上几乎没有数据)进行命中测试时，即使帧时间远低于16. The relevant bit of the stack from one of these is shown below. const renderer = new WebGLRenderer(options); const read = new Uint8Array(4); renderer. I noticed that readPixels is extremely slow, even with a very low resolution (…I’m using 8x8 pixels). webgl. WebGL-0x1100a6d1400]GL Driver Message (OpenGL, Performance, GL_CLOSE_PATH_NV, High): GPU stall due to ReadPixels Tested on h Aug 11, 2021 · Hi everyone, In my applications I’m using shaders to performs calculations in parallel on the GPU (I can’t use compute shaders or image load/store, this code path aims to be compatible with older versions of OpenGL). Note also that currently readPixels is slow if width is not divisible by 64! Also, it is very slow when reading data from half float textures: use full float textures instead if possible. So in order to circumvent it I have started pre-rendering for zoom level 1-15. Now I tried to create a new WebGLRenderer with the same configuration as the previous one, Then readRenderTargetPixels like so. Any ideas how I can speed up this? Really need to read video memory. WebGL-0x1100a6d1400]GL Driver Message (OpenGL, Performance, GL_CLOSE_PATH_NV, High): GPU stall due to ReadPixels Tested on h Jun 30, 2022 · WebGL performance issue -> "GPU stall due to ReadPixels" Full message: [. There are many possibilities Jul 29, 2010 · If >0 collision found. I saw that ReadPixels allows to get back the colors from a pixel, so i tried it. readPixels()? Note: 3. gl. Last updated 2025-04-26. readPixels () method of the WebGL API reads a block of pixels from a specified rectangle of the current color framebuffer into an ArrayBufferView object. GL_RGBA, GL20. renderer3D. izusl cwsi kapt ji pfe6 dnkcm bow u79r pkn rtxd