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GLSL · 26 Editing Failures and Context Recovery
Series contents · Technology map
Stage: Interaction, Postprocessing, and Cost Evaluation · Editable example · Storage ID: glsl-step-26
Goals and learning outcomes
- Apply shader edits safely.
- Design GPU resource recovery.
Prerequisites
Continue using the output and records from Unit 25. Before experimenting with Editing Failures and Context Recovery, preserve the previous inputs and reference outputs.
Key concepts and explanations
Safe Replacement
Keeping the last working program when a new shader fails lets editing continue. Replace the active program only with a validated new program.
Context Lifetime
After WebGL context restoration, previous GPU resources must be recreated. Save source and CPU inputs to prepare a recreation path.
Practice setup
First check the execution scope guidance on the example screen. The following describes the environment needed to extend the assignment in a separate project. This document-guided exercise requires your own implementation using WebGL2 and GLSL ES 3.00 in a separate localhost project. First check the GLSL version of existing examples and avoid mixing in 1.00 syntax.
The linked example is a starting point. It does not implement every task below. Complete work beyond its supported scope in a separate project.
Practice tasks
- Compile and link a candidate program in editor.js, replacing the current program only on success.
- Enter a syntax error and check the error line and whether the existing display is retained.
- Handle webglcontextlost and webglcontextrestored, and list resources to recreate in README.
Variables to observe
| Variable | Baseline | Change | Expected change / hypothesis |
|---|---|---|---|
| New source | valid source | contains a syntax error | Expect an error display while retaining the last working image. |
Predictions in this table are not measured results. Change one condition at a time and record why the actual result differs.
Completion criteria
- An erroneous input does not delete the existing program.
- The recovery path recreates buffers, textures, and programs and looks up uniforms again.
Self-check
- When should failed candidate shaders be deleted?
- Must UI state also be reset during context recovery?
Official references
Linked example and execution scope
Example source · Runtime environments and limits
Runs WebGL ShaderMaterial in the browser. Comparisons use a fixed 640×360 size; frame intervals are different from GPU time. The provided example only compiles an independent fragment shader, displays the raw compiler log, and retains the existing ShaderMaterial display. It does not install or replace a successful candidate program or implement context recovery.
Source code and records are not overwritten automatically. Resetting an existing example also preserves your notes.
Next learning
Previous: The Cost of Branches and Loops · Next: Quality Criteria and Regression Records