#Rendering

The engine uses Vulkan (via MoltenVK on macOS) for 3D rendering with support for glTF mesh loading and multi-entity draw calls.

#Mesh Loading

Load glTF models using NativeBridge.LoadMesh(). This parses the .glb file with cgltf and uploads vertex/index data to the GPU:

int meshId = NativeBridge.LoadMesh("models/Box.glb");

The returned meshId identifies the geometry on the GPU. You can share it across multiple entities.

#Procedural Primitives

The engine can also generate meshes for common shapes (box, sphere, plane, cylinder, capsule) without any external files. See Primitive Shapes for the full API and examples.

#Multi-Entity Rendering

Each entity gets its own draw slot in the renderer. The model matrix is passed via Vulkan push constants:

int entity1 = NativeBridge.CreateEntity(meshId);
int entity2 = NativeBridge.CreateEntity(meshId);  // same mesh, separate transform

The RenderSyncSystem automatically pushes each entity's Transform.ToMatrix() to its draw slot every frame.

#Render Pipeline

The engine has two Vulkan graphics pipelines sharing the same render pass:

#3D Scene Pipeline

• Vertex shader — UBO for view/projection matrices, push constant for per-entity model matrix
• Fragment shader — Samples per-material texture, multiplies with vertex color, then applies Blinn-Phong shading with up to 8 dynamic lights
• Depth testing — enabled, ensures correct draw order
• Back-face culling — enabled, improves performance

#UI Overlay Pipeline

• Vertex shader — 2D pixel coordinates converted to NDC via vec2 screenSize push constant
• Fragment shader — Samples R8 font atlas texture, multiplies by vertex color alpha
• No depth testing — UI always renders on top of the 3D scene
• Alpha blending — SRC_ALPHA / ONE_MINUS_SRC_ALPHA for transparent panels and anti-aliased text
• No backface culling — 2D quads rendered as triangle lists

The UI pipeline is used by the debug overlay and can be extended for HUD elements, menus, and other screen-space UI.

#Supported Model Format

• glTF Binary (.glb) — positions, normals, indices, UV coordinates, and base color textures are loaded. See Textures & UV Mapping for details.