Method draw

packages/melonjs/src/renderable/mesh.js:827–871

* Draw the mesh (automatically called by melonJS). Picks between two * projection paths based on the camera that was active when this mesh * was added to the world (captured in Mesh#onActivateEvent): * * - **Camera3d** → world-space output via Mesh#_projectVerticesWorld. *

(renderer, viewport)

	 * @param {Camera2d} [viewport] - the camera rendering this frame
	 */
	draw(renderer, viewport) {
		// Prefer the live viewport (per-draw) over the flag captured
		// at activation. Falling back to the flag when no viewport is
		// passed preserves test callers that call `draw(renderer)`
		// directly.
		const useWorldSpace =
			viewport !== undefined
				? viewport instanceof Camera3d
				: this._useWorldSpace === true;
		if (useWorldSpace) {
			if (this._worldSpace !== true) {
				this._setupWorldSpace();
			}
			// Camera3d path. The reflection bridge (Y-only negate) inverts
			// winding, so it needs the reversed indices to keep
			// `cullBackFaces: true` correct. The rotation bridge
			// (`rightHanded`: Y+Z negate) preserves winding, so the
			// original indices are already correct.
			this.indices = this.rightHanded
				? this._indicesOriginal
				: this._indicesReversed;
			// Emit FINAL world coordinates: the node origin is baked into
			// pos/depth and the geometry carries its own extent. The anchor
			// offset is suppressed for this path via `applyAnchorTransform`
			// (set in `preDraw`), so it does not leak into the view matrix.
			this._projectVerticesWorld(this.pos.x, this.pos.y, this.depth);
			// world-space normals — only when this mesh is lit (the unlit batcher
			// never reads `normals`, so projecting them otherwise is wasted
			// per-frame work; glTF meshes carry normals even when the scene has
			// no lights). No-op without source normals.
			if (this.lit === true) {
				this._projectNormalsWorld();
			}
		} else {
			// Camera2d / no-camera path: restore the original winding.
			// Important when the same Mesh instance was previously drawn
			// under Camera3d (`_setupWorldSpace` ran) and is now being
			// re-rendered under a 2D camera — without this restore the
			// reversed indices stay in place and front-facing triangles
			// get culled, leaving the model looking inside-out.
			this.indices = this._indicesOriginal;
			this._projectVertices(this.pos.x, this.pos.y, 1000);
		}
		renderer.drawMesh(this);
	}

	/**
	 * Compute a 2D convex hull polygon from the current projected vertices.