Parametric primitives
The five built-in shapes and the size and segment parameters that reshape them, before you start poly modeling.
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Every scene starts from five primitives. Each is parametric: it has size and resolution sliders in the Properties panel's Geometry section, and you can switch a primitive's type from the Primitive dropdown.
| Primitive | Parameters |
|---|---|
| Sphere | Radius · Width Segments · Height Segments |
| Box | Width · Height · Depth, plus W/H/D Segments for surface detail |
| Plane | Width · Height, plus W/H Segments |
| Cylinder | Radius · Height · Height Segments |
| Torus | Radius · Tube · Radial Segments · Tubular Segments |
Segments = smoothness and detail
Segment counts control how finely a shape is divided. More segments make a sphere rounder and give a surface enough geometry to show a displacement map's bumps. They also cost more to render, so dial them up only where you need them. There's a one-click Subdivide for displacement button that raises the count automatically when a material needs it.
Every segment field stops at 256, which is where the renderer clamps anyway. That keeps what you type equal to what draws, and keeps scene weight honest, since a count past the clamp used to be billed in full for triangles that never existed.
Cut: take part of a shape
A sphere, cylinder, or torus doesn't have to be whole. Select one and Properties shows a Cut section with angle fields in degrees. A hemisphere, a dome, a wedge, a half-pipe, or a horseshoe is a few numbers away, and no longer has to be faked by burying half a ball in something opaque.
| Primitive | Cut controls |
|---|---|
| Sphere | Top (where it starts, measured down from the pole) · Sweep down (90° is a hemisphere) · Around from · Around by (180° is half an orange). A Hemisphere button sets the top half in one click. |
| Cylinder | Around from · Around by (180° is a half pipe) · Open ends, which drops the flat caps so it's a tube rather than a can. |
| Torus | Arc: how much of the ring is drawn (180° is a horseshoe). |
Whole puts the full shape back. A cut shape renders double-sided automatically, so you can look into a dome from under its rim without the inside vanishing. A cut is not a saving, though: the segment counts spread across whatever survives, so a hemisphere at the same counts builds the same grid as the whole sphere, only denser, and scene weight charges it the same. The one cut that removes geometry is a cylinder's Open ends, which drops the two caps. If a dome is costing too much, lower its segments. The sphere's Sweep down is capped at what is left below Top, so the two can never run past the far pole and back. The smallest sweep is one degree, because a zero-length shape would be invisible and unpickable. Box and plane have no angle, so they have no Cut section, and imported meshes can't be cut.