bugpyFormex - Bugs: bug #41063, gl2 engine only renders with color...


bug #41063: gl2 engine only renders with color index (AMD cards only?)

Submitted by:  Benedict Verhegghe <bverheg>
Submitted on:  Thu 02 Jan 2014 10:57:48 AM UTC  
Category: RenderingSeverity: 4 - Important
Item Group: Functionality errorStatus: Works For Me
Privacy: PublicAssigned to: Benedict Verhegghe <bverheg>
Open/Closed: Open

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Mon 03 Feb 2014 10:42:51 AM UTC, comment #2:

The problem has been narrowed down to the not existing color buffer object (cbo) for single color.
In commit b874bc4 a workaround is added by creating a dummy, unused color buffer with a single color (red).

This seems to solve the problem on the one test machine that had the issue. The question raises whether we should
- make the creation of the dummy buffer configurable, as it is not needed for many other machines,
- or instead pass the single color via that color buffer, instead
of using a uniform.

Benedict Verhegghe <bverheg>
Project AdministratorIn charge of this item.
Thu 30 Jan 2014 10:06:15 AM UTC, comment #1:

If have been looking deeper into this and it turns out that element color and vertex color modes work, while object color (single color) and no color modes are not rendered at all.

Since no color and single color are treated the same in the shader, and element and vertex color also, I think the problem can be narrowed down to the objectColor mode in the shader, in combination with an AMD graphics card (or just my graphics card?).

If anybody has an AMD card in some machine running pyFormex, please test this: run the Cube example and see if the 'None' and 'Single' color option fail, while 'Face' and 'Full' work.

Note: if you are not sure what brand of graphics card you have, run the following command:

If the output contains 'AMD', 'ATI', 'Radeon', or 'Intel', I am interested in a test on that card.

Benedict Verhegghe <bverheg>
Project AdministratorIn charge of this item.
Thu 02 Jan 2014 10:57:48 AM UTC, original submission:

On a machine with an AMD (ATI) Radeon graphics card, rendering only works when using indexed colors, e.g. by setting property
numbers on the geometry.

Here is an example:

This renders as shown in attached gl2_amd2.png. When leaving out the setProp(0) from F, the rendering is as in gl2_amd2.png: F is not shown.

This happens on a machine with an AMD/ATI Radeon card using fglrx accelerated driver. I do not have the problem on any other machine equipped with NVDIA cards and nv driver.

Benedict Verhegghe <bverheg>
Project AdministratorIn charge of this item.


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Attach File(s):

Attached Files
file #30145:  gl2_amd2.png added by bverheg (3kB - image/png)
file #30146:  gl2_amd1.png added by bverheg (2kB - image/png)


Depends on the following items: None found

Items that depend on this one: None found


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    Follow 4 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Mon 03 Feb 2014 10:42:51 AM UTCbverhegStatusNone=>Works For Me
      Assigned toNone=>bverheg
    Thu 02 Jan 2014 10:57:48 AM UTCbverhegAttached File-=>Added gl2_amd2.png, #30145
      Attached File-=>Added gl2_amd1.png, #30146

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