Splat¶

Experimental screen-facing Gaussian footprint visual.

Status: experimental. Backends: native; WebGPU deferred (splat, alpha-blending). Primitive: screen-space Gaussian quads.

Preview And Links¶

Example: Splat
How-to: Choose a visual family, control depth, blending, and transparency
Related: Point, Sphere, Mesh

Use When¶

Use splat visuals for experimental translucent Gaussian marks where each item has an anisotropic screen-space footprint.

Avoid When¶

Use Point for stable circular sprites, Sphere for true 3D balls, or Mesh for surface geometry. Avoid splat as copy-paste starter code while it remains experimental.

Item And Data Model¶

Create with dvz_splat(scene, flags). One item is one screen-facing anisotropic Gaussian footprint. Upload N rows for every required attribute. The constructor enables alpha blending and depth testing; the first implementation uses center depth, no sorting, and no projected 3D covariance.

Attribute Contract¶

Attribute	Requirement/default	C type and cardinality	Python dtype and shape	Units/coordinates and constraints	Update route
`position`	Required; no documented default	`vec3[N]`	`float32`, `(N, 3)`	Center in authored visual coordinates.	Dense or range upload.
`color`	Required; no documented default	`DvzColor[N]`	`uint8`, `(N, 4)`	RGBA8. Scalar color is not supported by this family.	Dense or range upload.
`sigma`	Required; no documented default	`vec2[N]`	`float32`, `(N, 2)`	Gaussian x/y standard deviations in logical pixels; both components must be finite and strictly positive.	Dense or range upload.
`angle`	Required; no documented default	`float[N]`	`float32`, `(N,)`	Finite rotation angle in radians.	Dense or range upload.

Color and sigma accept explicitly configured constant/per-group sources. Dense arrays do not broadcast.

Constructor And Options¶

Constructor: dvz_splat(scene, flags); the canonical C example passes flags = 0.
The constructor selects alpha blending and enables depth testing. Change those only with the common visual-wide alpha/depth setters after considering translucent ordering limitations.
No canonical Python example is currently published; the top-level NumPy upload contract follows the shapes above.

Verified Usage Pattern¶

Upload all four arrays with dvz_visual_set_data_many(), then attach the visual. The canonical C example is the executable source.

Picking And Probing¶

Treat splat picking as experimental. The retained item identity is available, but translucent overlap, center-depth ordering, and lack of sorting limit interpretation.

Backend Notes¶

Native support exists. WebGPU is deferred in the manifest because splat rendering is outside the RC browser subset. The canonical example is intended for advanced visual-family inspection rather than as a first example.

Canonical Example¶

Field	Value
Source	`examples/c/visuals/splat.c`
Gallery	Splat
Build	`just example-c visuals/splat`
Smoke	`./build/examples/c/visuals/splat --png`
Validation	`smoke+screenshot`