Search:

Type: Posts; User: Bruce Sherwood

Page 1 of 3 1 2 3

Search: Search took 0.00 seconds.

  1. Replies
    6
    Views
    4,148

    Re: Issues with using ReadPixels

    I'm sorry, but I don't understand the question. Surely one needs to render to a texture in order to be able to read the pixel color from the texture? Can you explain more fully how you would...
  2. Re: Details about handling transparency with depth peeling

    Thanks for the news report. I guess you could try just one transparent peel, just to see what happens? That would only require C0, C1, and D0, right?
  3. Re: Details about handling transparency with depth peeling

    I'm delighted that you found my post to be useful. Thanks for the report on the Galaxy S3. I had wondered how many texture units are provided on mobile devices but didn't have a device I could try....
  4. Replies
    4
    Views
    2,175

    Re: Shader compiler fragility?

    I did a lot of work to ensure that I send to each shader only that data that is actually referenced and used by that shader, and that made mouse picking and transparency work on all platforms,...
  5. Replies
    2
    Views
    2,178

    Re: Saving data from the Fragment shader

    It sounds like you might be asking two questions. The answer to the question, "Can I write more than 16 bytes of data (a vec4 is four 32-bit bytes) per fragment shader operation?" is clear: No. In...
  6. Replies
    4
    Views
    2,175

    Re: Shader compiler fragility?

    While it is all too fresh in my mind, I should report a very clear example of a problem with WebGL shaders that I've alluded to before.

    In the process of developing an important new feature for...
  7. Re: Details about handling transparency with depth peeling

    I just came across a discussion of how to implement "Fast Approximate Anti-Aliasing" (FXAA) to get around the problem that the use of framebuffer objects turns off anti-aliasing:
    ...
  8. Details about handling transparency with depth peeling

    Pixel-level transparency based on depth peeling

    Handling transparency correctly in WebGL is challenging. A standard technique is to order the centers of objects according to their z depth from the...
  9. Replies
    4
    Views
    2,175

    Re: Shader compiler fragility?

    I made a mistake in posting the URL, which should be this:

    http://www.glowscript.org/#/user/GlowSc ... /Examples/
  10. Replies
    6
    Views
    4,148

    Re: Issues with using ReadPixels

    I recently implemented mouse picking in GlowScript (glowscript.org). For object with id number N, I create a false color like this:

    function id_to_falsecolor(N) { // convert integer object...
  11. Replies
    4
    Views
    2,175

    Re: Shader compiler fragility?

    More on this:

    As you know, I recently implemented transparency through depth peeling in GlowScript, with what I consider to be adequately clean code. Then it developed that it didn't work on...
  12. Replies
    4
    Views
    2,175

    Shader compiler fragility?

    After releasing transparency capabilities in GlowScript (glowscript.org) I discovered that neither transparency nor mouse picking was working on Ubuntu and the MacBook Pro running Snow Leopard (works...
  13. Re: Depth peeling successfully implemented in WebGL

    Upon further investigation, I'm convinced it's a driver problem, not a WebGL problem. In addition to other evidence, it's highly suggestive that the problem arises specifically in environments where...
  14. Re: Depth peeling successfully implemented in WebGL

    I've discovered to my chagrin that this depth peeling transparency scheme fails on some platforms, and it apparently is a graphics driver issue. Until a few days ago, I was using only a few shader...
  15. Depth peeling successfully implemented in WebGL

    In the easy-to-use WebGL-based GlowScript 3D programming environment (glowscript.org) you can now specify the opacity of an object (other than curve, ring, and helix). The following statement creates...
  16. Replies
    4
    Views
    2,928

    Re: Depth peeling

    "Depth peeling" is an interesting algorithm for handling transparency. The problem it solves is this: Suppose you have two intersecting objects, both transparent. A simple scheme like that used in...
  17. Replies
    4
    Views
    2,928

    Re: Depth peeling

    I was wrong. It's not the texture creation that's taking 10 seconds (which didn't make sense). It's the creation of the shader programs. They've gotten larger and more complex. Perhaps I need to...
  18. Replies
    4
    Views
    2,928

    Re: Depth peeling

    I've made an experimental implementation of depth peeling in GlowScript (glowscript.org) to handle transparency. This is the third GPU project I've attempted (pick, a success; extent, a failure,...
  19. Replies
    4
    Views
    2,928

    Re: Depth peeling

    I guess just writing down my problem was sufficient. I found a simple programming error (wrong variable used in a for loop). Now I can really work on the depth peeling algorithm.
  20. Replies
    4
    Views
    2,928

    Depth peeling

    For the project GlowScript (glowscript.org) I've written the code to handle transparency using depth peeling but alas it doesn’t work. I think I've narrowed the problem down to the following test...
  21. Replies
    0
    Views
    1,570

    Compute the extent of a scene

    GlowScript (glowscript.org) is an environment that enables even
    novice programmers to write JavaScript programs that generate
    3D animations using WebGL. For example, the shortest GlowScript...
  22. Replies
    1
    Views
    2,011

    Re: Reading a file to make a texture

    Ah. I finally discovered that png and jpg files are also accepted, not just gif. Dunno where there is any documentation on the acceptable file formats (by experiment, targa files are not accepted).
  23. Replies
    1
    Views
    2,011

    Reading a file to make a texture

    I used Photoshop to convert a jpeg photo into a targa bump map file. I want to read up this file from the directory containing the JavaScript code and do a little bit of processing to create a bump...
  24. Replies
    3
    Views
    2,532

    Re: GPU picking on Ubuntu

    I "fixed" my problem -- I'm able to pick on Linux (as well as on Windows and Mac), but I don't understand.

    To pick, I bound to the hidden canvas (with antialiasing turned off) a fragment shader...
  25. Replies
    3
    Views
    2,532

    Re: GPU picking on Ubuntu

    Here is the actual code I'm using:

    this.__canvas_element = document.createElement('canvas')
    this.__pick_element = document.createElement('canvas')
    ...
Results 1 to 25 of 58
Page 1 of 3 1 2 3