GLES possible additional <internalformat> extensions

[devshgraphicsprogramming]

(A) Extensions I'm sure that are NOT in GLES 3.1 core

https://www.khronos.org/registry/OpenGL/extensions/AMD/AMD_compressed_3DC_texture.txt https://www.khronos.org/registry/OpenGL/extensions/AMD/AMD_compressed_ATC_texture.txt https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_compression_dxt1.txt https://www.khronos.org/registry/OpenGL/extensions/NV/NV_texture_compression_s3tc.txt https://www.khronos.org/registry/OpenGL/extensions/NV/NV_texture_compression_s3tc_update.txt https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_compression_s3tc.txt https://www.khronos.org/registry/OpenGL/extensions/IMG/IMG_texture_compression_pvrtc.txt https://www.khronos.org/registry/OpenGL/extensions/ANGLE/ANGLE_texture_compression_dxt.txt https://www.khronos.org/registry/OpenGL/extensions/OES/OES_texture_compression_astc.txt https://www.khronos.org/registry/OpenGL/extensions/KHR/KHR_texture_compression_astc_hdr.txt https://www.khronos.org/registry/OpenGL/extensions/NV/NV_texture_compression_latc.txt https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_pvrtc_sRGB.txt https://www.khronos.org/registry/OpenGL/extensions/IMG/IMG_texture_compression_pvrtc2.txt https://www.khronos.org/registry/OpenGL/extensions/OES/OES_compressed_ETC1_RGB8_texture.txt (its not etc2) https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_compression_s3tc_srgb.txt https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_compression_bptc.txt

(B) Suspected non core Extensions

https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_color_buffer_half_float.txt read carefully https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_color_buffer_float.txt read carefully https://www.khronos.org/registry/OpenGL/extensions/NV/NV_packed_float.txt (NV_packed_float_linear a linear filtered sampler, NV_packed_float for renderable, storage and nearest sampler) https://www.khronos.org/registry/OpenGL/extensions/MESA/MESA_bgra.txt https://www.khronos.org/registry/OpenGL/extensions/QCOM/QCOM_render_shared_exponent.txt RGB9E5 as a renderable https://www.khronos.org/registry/OpenGL/extensions/NV/NV_image_formats.txt (adds a lot of desktop GL formats) https://www.khronos.org/registry/OpenGL/extensions/NV/NV_shader_atomic_fp16_vector.txt it interacts with a lot of extensions so please read the spec! https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_sRGB_RG8.txt https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_sRGB_R8.txt https://www.khronos.org/registry/OpenGL/extensions/NV/NV_sRGB_formats.txt (stronger than the above two) https://www.khronos.org/registry/OpenGL/extensions/OES/OES_texture_stencil8.txt https://www.khronos.org/registry/OpenGL/extensions/OES/OES_shader_image_atomic.txt (atomic Image and BufferView only core in ES 3.2, 3.1 needs an extension) https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_render_snorm.txt https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_norm16.txt https://www.khronos.org/registry/OpenGL/extensions/OES/OES_texture_buffer.txt (ability to use BufferViews at all) https://www.khronos.org/registry/OpenGL/extensions/OES/OES_vertex_type_10_10_10_2.txt OES_texture_float_linear OES_depth_texture_cube_map • EXT_texture_type_2_10_10_10_REV • NV_fbo_color_attachments • NV_read_buffer • NV_read_depth_stencil

(C) Extensions and Features added to GLES 3.1 core (I'm sure of)

• OES_texture_half_float • OES_texture_half_float_linear • OES_texture_float https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_sRGB.txt (but doesn't provide R8_SRGB) https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_format_BGRA8888.txt https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_read_format_bgra.txt https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_type_2_10_10_10_REV.txt https://www.khronos.org/registry/OpenGL/extensions/OES/OES_vertex_half_float.txt (half float usable as vertex format) https://www.khronos.org/registry/OpenGL/extensions/OES/OES_texture_float_linear.txt & https://www.khronos.org/registry/OpenGL/extensions/OES/OES_texture_float.txt ( 32bit and 16bit float textures used as sampled formats) https://www.khronos.org/registry/OpenGL/extensions/NV/NV_read_depth_stencil.txt (stuff that completes the support of depth and stencil formats) https://www.khronos.org/registry/OpenGL/extensions/EXT/EXT_texture_rg.txt (single and dual channel support, but no R8_SRGB or RG8_SRGB) https://www.khronos.org/registry/OpenGL/extensions/OES/OES_packed_depth_stencil.txt (depth+stencil formats) • 32-bit, 16-bit, and 8-bit signed and unsigned integer textures and vertex attributes • 11/11/10 floating-point RGB textures (same as NV_packed_float_linear ? ) • shared exponent RGB 9/9/9/5 textures (same as NV_packed_float_linear ? ) • 10/10/10/2 unsigned normalized and unnormalized integer textures (unsure if wholly equivalent to EXT_texture_type_2_10_10_10_REV) • 8-bit-per-component signed normalized textures • ETC2/EAC texture compression formats • depth textures • 24-bit depth textures • 24/8 depth/stencil extures • 32-bit depth and 32F/8 depth/stencil textures • Stencil texturing • Multisample formats for immutable textures

Plan of action

1. Remove any conditionals and checks for extensions listed in (C)
2. Add all the formats unconditionally to the switch cases for formats provided by GLES 3.1 spec and (C)
3. Add the formats introduced by (A) with cnditional extension checks
4. Check if new formats introduced by (B) are not in the GLES 3.1 spec and produce a filtered list (D)
5. Read valid usage for glBindImage, glTexBuffer, glFramebufferTexture to know further format constraints on BufferView, Image Storage, color attachment, etc.
6. Implement checks for formats provided by D
7. disregard the distrinction between filterable and non filterable GLES samplers where it could differ for a format due to an extension (but document it exists)
8. Fix the 2 little mistakes in @achal's code

P.S. Before checking extensions, ensure you handle ANDROID_extension_pack_es31a implicitly enabling others.