KhronosGroup / KhronosGroup/WebGL
Require gl_PointSize for points rendering or define a default value
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Description
When a vertex shader doesn't set gl_PointSize value (while drawing using gl.POINTS mode), the behavior is undefined by OpenGL ES:
GLSL ES 1.0 (section 7.1):
mediump float gl_PointSize; // may be written to
If any of these variables are not written to, their values are undefined.
GLSL ES 3.0 (section 7.1):
If
gl_PointSizeis not written to, its value is undefined in subsequent pipe stages.
Chrome and Firefox show different behavior: Chrome doesn't render anything while Firefox seems to default to 1.0. In spirit of #2780, the WebGL spec should be adjusted.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start with the WebGL specification discussion in this issue and compare the GLSL ES 1.0 and 3.0 requirements cited here, then review the related context in issue #2780. Done means deciding whether points rendering should require gl_PointSize or define a default value and updating the WebGL specification accordingly.
Written by the indexing model from the issue text.
Assessment
- Domain
- computer-graphics
- Issue type
- Feature
- Difficulty
- 5/5
- Estimated time
- Over a week
- Activity status
- Stale
- Clarity
- Needs clarification
- Newbie friendliness
- 30/100