# Graphics Backend

The `simvx.graphics` package provides GPU-accelerated Vulkan rendering for SimVX.

## Architecture

SimVX uses a **GPU-driven forward renderer** — all draw calls use `vkCmdDrawIndexedIndirect` with no Python loops during rendering. Object transforms, materials, and draw commands are packed into flat NumPy arrays and uploaded to SSBOs once per frame.

### Key Features

- **Multi-draw indirect** — thousands of objects in a single Vulkan draw call
- **SSBO-driven data** — transforms, materials, and lights in Shader Storage Buffer Objects
- **Bindless textures** — up to 4096 textures in a single descriptor array
- **Multi-viewport** — split-screen, picture-in-picture, offscreen render targets
- **Frustum culling** — CPU-side per-viewport bounding-sphere culling

## Guides

- {doc}`app` — App class, game loop, and backend swap
- {doc}`testing` — Headless rendering, pixel assertions, and visual regression tests

## API Reference

See {py:mod}`simvx.graphics` for the complete API.