Dynamic texture stage

[alemuntoni]

Textures are not bound to fixed stages anymore when drawing mesh surface.
Stages are used dynamically only when a texture is actually needed.
The stage for each texture type is then encoded on uniforms (packed in DrawableMeshUniforms).

[Copilot]

Pull request overview

This PR refactors the texture binding system for mesh rendering to use dynamic texture stages instead of fixed stage assignments. Previously, textures were bound to predefined stages (VCL_MRB_TEXTURE0-5), but now stages are allocated dynamically as needed and the stage information is encoded in shader uniforms using a packed 32-bit integer (4 bits per texture type).

Changes:

• Introduced dynamic texture stage allocation where texture stages are assigned at runtime and encoded in DrawableMeshUniforms
• Removed texture availability tracking from MaterialUniforms in favor of stage-based availability checks
• Consolidated PBR-related macros from pbr_macros.h into mesh_render_buffers_macros.h

Reviewed changes

Copilot reviewed 15 out of 15 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
vclib/render/shaders/vclib/bgfx/pbr_common.sh	Updated include path and formatting for macro definitions
vclib/render/shaders/vclib/bgfx/drawable/uniforms/material_uniforms.sh	Removed u_pbr_texture_settings uniform definition
vclib/render/shaders/vclib/bgfx/drawable/uniforms/drawable_mesh_texture_uniforms.sh	New file implementing dynamic texture stage functions with bit-field encoding
vclib/render/shaders/vclib/bgfx/drawable/drawable_mesh/surface/tex_wedge.sh	Updated to use new baseColorTex() function instead of direct texture2D
vclib/render/shaders/vclib/bgfx/drawable/drawable_mesh/surface/tex_vertex.sh	Updated to use new baseColorTex() function instead of direct texture2D
vclib/render/shaders/vclib/bgfx/drawable/drawable_mesh/surface/surface_uber_in.sh	Removed SAMPLER2D declarations, now using texture functions from drawable_mesh_texture_uniforms.sh
vclib/render/shaders/vclib/bgfx/drawable/drawable_mesh/surface/fs_surface_uber_pbr.sc	Updated all texture calls to use new availability checks and texture functions
vclib/render/shaders/vclib/bgfx/drawable/drawable_mesh/surface/fs_surface_uber.sc	Updated texture calls to use new baseColorTex() function
vclib/render/include/vclib/bgfx/drawable/uniforms/material_uniforms.h	Removed texture availability parameter from set() function and related logic
vclib/render/include/vclib/bgfx/drawable/uniforms/drawable_mesh_uniforms.h	Added texture stage encoding/decoding functions and TextureType enum
vclib/render/include/vclib/bgfx/drawable/mesh/pbr_macros.h	File deleted, macros moved to mesh_render_buffers_macros.h
vclib/render/include/vclib/bgfx/drawable/mesh/mesh_render_buffers_macros.h	Consolidated PBR macros, removed fixed texture stage definitions
vclib/render/include/vclib/bgfx/drawable/mesh/mesh_render_buffers.h	Implemented dynamic texture binding with stage tracking, changed uniform names
vclib/render/include/vclib/bgfx/drawable/drawable_mesh_bgfx.h	Updated to call resetTextureStages() and handle dynamic stage allocation
vclib/render/include/vclib/bgfx/drawable/drawable_environment.h	Changed BRDF LUT uniform name from "s_brdf_lut" to "s_tex5"

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[Copilot]

Misleading comment: the comment says "use y" but the code uses sMeshData[2], which is the z component, not y. The comment should say "use z" or be removed entirely since it's redundant with the function name setYTextureStage.

Suggested change

	if (toUnderlying(type) < 8) { // use y
	if (toUnderlying(type) < 8) { // use z component (sMeshData[2])

[Copilot]

Bug: texture stages need to be reset before binding textures for each chunk. Currently, resetTextureStages is only called once before the loop (line 217), but when different chunks have different materials with different numbers of textures, stale texture stage data from previous chunks will persist. For example, if chunk 0 has 3 textures and chunk 1 has 2 textures, chunk 1 will still have the third texture stage set from chunk 0. Add a call to DrawableMeshUniforms::resetTextureStages() at the beginning of the loop, before line 233 where bindTextures is called.

Suggested change

	/* TEXTURES */
	/* TEXTURES */
	// Reset texture stages for each chunk to avoid stale bindings
	DrawableMeshUniforms::resetTextureStages();