b3dScaleDetailTexture

Scales entity detail texture UV (scaleU/V, requires BBR_TEXTURE_UV flag, auto-clones shared materials). Takes entityHandle (mesh entity handle), textureHandle (texture handle identifying which detail layer), scaleU (horizontal UV scale double), scaleV (vertical UV scale double). Returns nothing. Finds detail layer containing textureHandle, updates detailTextureScale[i] to {scaleU, scaleV}, controls detail texture repeat/stretch. Requires mesh.allowsUVTransforms = true (set via BBR_TEXTURE_UV flag in b3dCreateMesh or b3dLoadMesh). Mesh entities only.

This function scales entity-level detail texture coordinates. UV scaling: scaleU/V multiply texture coordinates (scaleU=2.0 repeats texture twice horizontally, scaleU=0.5 stretches texture to half size). UV transform requirement: mesh must be created with BBR_TEXTURE_UV flag, prints helpful error if mesh.allowsUVTransforms = false. Layer identification: searches material detailTextureIndex[0-2] for matching textureHandle (compares both texture handle and SRV heap index for compatibility), finds which layer contains this texture, updates corresponding detailTextureScale[i]. Material handling: surface-based meshes (procedural shapes) update all surface materials directly (all surfaces get same detail scale), loaded meshes (GLB models) auto-clone material if shared (calls EnsureUniqueMaterial first), applies scale to entity's material. Use cases: (1) Detail tiling (scaleU=4.0, scaleV=4.0 to repeat detail 4x4 times for fine patterns), (2) Anisotropic scaling (scaleU=2.0, scaleV=1.0 for horizontal stretching), (3) Uniform scaling (scaleU=scaleV for proportional resize), (4) Dynamic tiling (animate scale for scrolling effects), (5) Resolution matching (scale detail to match mesh size). Common patterns: tile 4x4 b3dScaleDetailTexture(entity, detailTex, 4.0, 4.0), stretch horizontally b3dScaleDetailTexture(entity, detailTex, 2.0, 1.0), animate scrolling scaleU = scaleU + 0.01 then b3dScaleDetailTexture(entity, detailTex, scaleU, scaleV). Typical usage: set scale > 1.0 to tile detail texture for fine patterns (scratches, noise), set scale < 1.0 to stretch detail texture for large features, set different scaleU/V for directional effects, animate for scrolling textures. Entity-level vs surface-level: b3dScaleDetailTexture applies to entire entity (all surfaces on surface-based mesh, single material on loaded mesh), b3dScaleSurfaceDetailTexture applies to specific surface (per-face control), use entity-level for uniform scaling. Material auto-cloning: loaded meshes (GLB) automatically call EnsureUniqueMaterial if shared (prevents affecting other instances), surface-based meshes don't need cloning (each has own materials). Texture handle matching: searches for textureHandle or matching SRV heap index (handles both direct handle and SRV index input, flexible compatibility). Performance: O(1) for loaded mesh (finds layer, updates 2 floats after clone), O(N) for surface-based mesh with N surfaces (all surfaces searched and updated), scale applied in shader. Texture not found: prints error if textureHandle not in any detail layer (must call b3dSetEntityDetailTexture first). Validation: prints error if invalid entity handle, entity not mesh, UV transforms not allowed, entity has no valid material, texture not found in detail layers. Related: b3dPositionDetailTexture offsets entity detail texture UV, b3dRotateDetailTexture rotates entity detail texture UV, b3dSetEntityDetailTexture adds detail layer (required before scaling), b3dScaleSurfaceDetailTexture scales surface-specific detail (per-face control), b3dCreateMesh creates mesh with BBR_TEXTURE_UV flag.