WebGL swizzle operation changes value in uninvolved variable

Confirmed Issue #8503597 • Assigned to Rafael C.


Prime O.
Aug 16, 2016
This issue is public.
Found in
  • Microsoft Edge
Found in build #
Reported by 1 person

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Steps to reproduce

  1. Visit https://www.shadertoy.com/view/Xtt3WB
  2. Observe the erroneous rendering
  3. Change the shader code to activate the #define NO_GLITCH preprocessor directive.
  4. Press play and observe the difference.


Comments and activity

  • Microsoft Edge Team

    Changed Assigned To to “Brad E.”

  • Thanks for the feedback on Edge.

    Whenever I test this out on multiple builds (14905 & 10586) I see the same rendering that Chrome Canary 54 does.

    Can you provide a dxdiag for me so we can look into some of the hardware details needed to repro this?

    Best regards,
    The MS Edge Team

  • I’ve added my dxdiag.txt file.

    This shader also displays incorrectly (but in a totally different way) on iPhone 6S when viewed in the free ShaderToy app.

  • The shader code depends heavily on the specifics of the compiler and I had to try a lot of arrangements before I got it to calculate two different results from the same formula for demonstration purposes. Unfortunately this makes it precariously balanced.

    So I think it should be reproed against the exact same Edge version as mine:
    Microsoft Edge 39.14901.1000.0
    Microsoft EdgeHTML 14.14901

  • Microsoft Edge Team

    Changed Assigned To to “Rick J.”

    Changed Assigned To to “Rico M.”

    Changed Assigned To from “Rico M.” to “Rafael C.”

    Changed Status to “Confirmed”

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