EXT_texture_compression_rgtc
WebGL Extension
What is EXT_texture_compression_rgtc?
The EXT_texture_compression_rgtc extension is part of the WebGL API and exposes 4 RGTC compressed texture formats. RGTC is a block-based texture compression format suited for unsigned and signed red and red-green textures (Red-Green Texture Compression). It provides 4 formats: COMPRESSED_RED_RGTC1_EXT, COMPRESSED_SIGNED_RED_RGTC1_EXT, COMPRESSED_RED_GREEN_RGTC2_EXT, and COMPRESSED_SIGNED_RED_GREEN_RGTC2_EXT. Each format uses 64-bit blocks for 4x4 texel regions, equivalent to BC4 and BC5. Use with compressedTexImage2D() and compressedTexSubImage2D().
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- Graphics card model and capabilities
- GPU driver version
- Browser version and vendor
- Operating system
Usage in Web Scraping & Anti-Bot Bypass
Modern anti-bot systems verify WebGL extensions to detect automated browsers. Mismatches between GPU hardware and available extensions are strong bot signals.
What Anti-Bot Systems Check:
- Extension availability: Does the reported GPU support these extensions?
- Extension combinations: Are the extensions typical for this GPU model?
- Consistency checks: Do reported extensions match other GPU signals?
- Missing extensions: Are expected extensions for this GPU absent?
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