Renderer

Renderer

renderers/renderer.mojo. The Renderer turns a scene, its assets and a camera into an image. prepare makes screen-space triangles. render also fills them on the CPU.

three.js: WebGLRenderer.render(scene, camera), plus the assets argument that Mojo needs.

Construct one

var renderer = Renderer(320, 240)
var fast = Renderer(1280, 720, workers=available_workers())

Member	Meaning
Renderer(width, height, workers=1)	An image size and a thread count.
set_workers(workers)	Change the thread count. At least one.
set_background(color)	The clear color.
set_shading(mode)	What a fragment's color comes from. See below.
prepare(scene, assets, camera) -> List[RasterVertex]	Transform, clip and project every mesh.
render(scene, assets, camera) -> Framebuffer	prepare, then rasterize and resolve.
available_workers() -> Int	One per logical core.

scene.update() must run before prepare or render. The renderer reads world matrices and does not recompute them.

Shading modes

Mode	A fragment's color is
SHADE_TEXTURE	The material color, times its texture, times the light, plus the emissive times its map. The default.
SHADE_LIT	The material color times the light, plus the emissive. Textures are ignored.
SHADE_UV	The texture coordinates, as red and green. A debug view.

set_shading refuses a mode that is none of the three.

What prepare does

For each mesh, in draw order:

1. Transform the positions to world space and camera space.
2. Transform the normals with the normal matrix, or compute a face normal.
3. Clip each triangle against the near and far planes.
4. Project each corner to pixels and keep 1 / w.
5. Cull faces that the material's side does not draw.
6. Flip the normal of a face seen from behind.

The output is one flat list, three RasterVertex per triangle. Both rasterizers consume it. See Rasterization.

Draw order

Opaque meshes come first, nearest first. Translucent meshes follow, furthest first. The order is per mesh, by the depth of its node's origin. See Why transparency is sorted.

Workers

With more than one worker, the image is cut into horizontal bands. Each band is drawn on its own thread. The result is byte for byte the same as one thread. See Why the CPU renderer uses bands.

The default is one worker. The coverage tool needs probe records in order.

Errors

prepare raises in three cases. A mesh names a node, geometry or material that does not exist. A material names a texture or an emissive map that does not exist. A geometry has no positions.

Performance

make bench-scene times each stage on a sphere of twelve thousand triangles. At 1280 by 720 with 24 workers a frame takes about 19 milliseconds. prepare is single threaded and is the largest stage.