Struct RenderOptions 

pub struct RenderOptions {
    pub backend: BackendPreference,
    pub gpu: GpuRendererSettings,
    pub clear_sky: Rgb,
    pub gpu_mip_scan_dist: f32,
    pub gpu_chunk_upload_budget: u32,
    pub gpu_clip_upload_budget: u32,
    pub gpu_sprite_lod_px: f32,
    pub cpu_max_grid_vsid: u32,
    pub cpu_render_threads: usize,
}

Construction-time options for SceneRenderer::new.

Environment overrides (QE-C6)

Each GPU tuning knob below has a ROXLAP_* escape hatch, so a shipped binary can be re-tuned from the shell. All of them are read once, at SceneRenderer construction (never per frame), the env value wins over the programmatic one, and unparseable values are dropped with a log::warn!. On wasm there is no process environment and the field values apply as-is.

variable	overrides	values
ROXLAP_GPU_POWER	gpu.power_preference	low / high
ROXLAP_GPU_SPRITE_LOD_PX	gpu_sprite_lod_px	f32, screen px
ROXLAP_GPU_MIP_SCAN_DIST	gpu_mip_scan_dist	f32, world units
ROXLAP_GPU_CHUNK_BUDGET	gpu_chunk_upload_budget	u32, 0 = unbounded
ROXLAP_GPU_CLIP_BUDGET	gpu_clip_upload_budget	u32, 0 = unbounded

Other ROXLAP_* variables you may have seen (ROXLAP_GPU, ROXLAP_SCENE, ROXLAP_CAPTURE, …) belong to the demo hosts, not the library — backend selection is backend, decided by your code.

Fields

backend: BackendPreference

Which backend to build (QE.7b — replaces want_gpu: bool; migrate want_gpu: true → BackendPreference::PreferGpu, false → BackendPreference::Cpu).

gpu: GpuRendererSettings

Settings forwarded to roxlap_gpu::GpuRenderer when the GPU backend is selected.

clear_sky: Rgb

Packed 0x00RRGGBB (alpha ignored) the empty/clear frame fills with until a scene render lands. Also the CPU sky-miss colour default if a frame supplies none.

gpu_mip_scan_dist: f32

GPU scene-grid LOD scan distance in world units (GPU.11.1): rays farther than this from the camera sample coarser chunk mips. QE.2a — construction-time here (was a per-frame FrameParams field); the ROXLAP_GPU_MIP_SCAN_DIST env var still overrides it as a user-side escape hatch. Ignored by the CPU backend (its mip ladder comes from OpticastSettings::mip_scan_dist).

gpu_chunk_upload_budget: u32

GPU per-frame dirty-chunk install budget (QE.2c — was env-only ROXLAP_GPU_CHUNK_BUDGET, which still overrides). Each chunk install issues several queue.write_buffer calls; a big batch can exhaust the device staging pool (seen as egui-wgpu panics on Mesa/NVK while flying fast). Small budget = bounded per-frame writes, more terrain pop-in when moving quickly. 0 = unbounded.

gpu_clip_upload_budget: u32

GPU frames-per-staging-flush while registering a flipbook clip (QE.2c — was env-only ROXLAP_GPU_CLIP_BUDGET, which still overrides). 0 = unbounded.

gpu_sprite_lod_px: f32

GPU sprite mip-LOD threshold (QE.8; ROXLAP_GPU_SPRITE_LOD_PX overrides): the pass steps to a coarser sprite mip once a mip-0 voxel would project smaller than this many screen pixels. 1.0 (the default) is the “don’t go sub-pixel” threshold and keeps GPU sprites visually identical to the CPU backend (which has no sprite LOD); raise it to trade sprite fidelity for distant-sprite speed (the pre-QE.8 behaviour was 4.0, which visibly densified thin/hollow translucent models at range).

cpu_max_grid_vsid: u32

👎Deprecated since 0.22.0:

ignored — the DDA renderer replaced the strip-parallel opticast and needs no scratch-pool pre-sizing

Unused. Sized the strip-parallel opticast’s per-frame scratch pool; the per-pixel DDA renderer that replaced it needs no pre-sizing, so the value is ignored.

cpu_render_threads: usize

👎Deprecated since 0.22.0:

ignored — the DDA renderer parallelises over the rayon pool; bound it with RAYON_NUM_THREADS

Unused. Set the strip-parallel opticast’s thread count; the DDA renderer parallelises internally over the rayon pool (bound it with RAYON_NUM_THREADS if needed), so the value is ignored.

Trait Implementations

impl Clone for RenderOptions

fn clone(&self) -> RenderOptions

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Default for RenderOptions

fn default() -> Self

Returns the “default value” for a type.