Systems

/**
 * Base interface for all rendering systems
 * Systems handle specific aspects of the WebGL pipeline
 */
interface ISystem {
  /** Destroy system and cleanup resources */
  destroy(): void;
}

interface ISystemConstructor<R = Renderer> {
  /** System constructor signature */
  new (renderer: R): ISystem;
}

// Available on Renderer instance
interface RendererSystems {
  /** Mask rendering and stencil management */
  mask: MaskSystem;
  /** WebGL context management */
  context: ContextSystem;
  /** WebGL state tracking and optimization */
  state: StateSystem;
  /** Shader compilation and management */
  shader: ShaderSystem;
  /** Texture uploading and binding */
  texture: TextureSystem;
  /** Vertex buffer management */
  buffer: BufferSystem;
  /** Geometry and vertex array objects */
  geometry: GeometrySystem;
  /** Framebuffer and render target management */
  framebuffer: FramebufferSystem;
  /** Scissor testing */
  scissor: ScissorSystem;
  /** Stencil buffer operations */
  stencil: StencilSystem;
  /** Projection matrix management */
  projection: ProjectionSystem;
  /** Texture garbage collection */
  textureGC: TextureGCSystem;
  /** Filter rendering pipeline */
  filter: FilterSystem;
  /** Render texture management */
  renderTexture: RenderTextureSystem;
  /** Batch rendering optimization */
  batch: BatchSystem;
}

/**
 * MaskSystem handles mask rendering and clipping
 * Uses stencil buffer and scissor testing for graphics clipping
 */
class MaskSystem implements ISystem {
  /** Whether masking is enabled */
  enableScissor: boolean;
  /** Current alpha mask pool */
  alphaMaskPool: SpriteMaskFilter[];
  /** Current alpha mask index */
  alphaMaskIndex: number;

  constructor(renderer: Renderer);

  /**
   * Apply mask to current rendering
   * @param target - Object being masked
   * @param maskData - Mask information
   */
  push(target: IRenderableObject, maskData: MaskData): void;

  /**
   * Remove current mask
   * @param target - Object being unmasked
   * @param maskData - Mask information  
   */
  pop(target: IRenderableObject, maskData?: MaskData): void;

  /**
   * Setup scissor mask
   * @param maskData - Scissor mask data
   */
  pushScissorMask(maskData: MaskData): void;

  /** Remove scissor mask */
  popScissorMask(): void;

  /**
   * Setup stencil mask
   * @param maskData - Stencil mask data
   */
  pushStencilMask(maskData: MaskData): void;

  /** Remove stencil mask */
  popStencilMask(): void;

  /** Destroy mask system */
  destroy(): void;
}

/**
 * TextureSystem manages GPU texture operations
 * Handles binding, uploading, and texture unit management
 */
class TextureSystem implements ISystem {
  /** Maximum texture units available */
  maxTextures: number;
  /** Current texture bindings */
  boundTextures: BaseTexture[];
  /** Current active texture unit */
  currentLocation: number;
  /** Unknown texture for missing textures */
  unknownTexture: BaseTexture;
  /** Empty texture array for batch rendering */
  emptyTextures: BaseTexture[];

  constructor(renderer: Renderer);

  /**
   * Bind texture to specific texture unit
   * @param texture - Texture to bind
   * @param location - Texture unit (0-31)
   */
  bind(texture: Texture | BaseTexture, location?: number): void;

  /** Reset all texture bindings */
  reset(): void;

  /** Unbind all textures */
  unbind(texture?: BaseTexture): void;

  /** Destroy texture system */
  destroy(): void;
}

/**
 * GeometrySystem manages vertex array objects and attribute binding  
 * Handles geometry rendering and vertex buffer setup
 */
class GeometrySystem implements ISystem {
  /** Whether VAOs are supported */
  hasVao: boolean;
  /** Whether instanced rendering is supported */
  hasInstance: boolean;
  /** Whether multiple render targets are supported */
  canUseUInt32ElementIndex: boolean;

  constructor(renderer: Renderer);

  /**
   * Bind geometry for rendering
   * @param geometry - Geometry to bind
   * @param shader - Shader program to use
   */
  bind(geometry?: Geometry, shader?: Shader): void;

  /** Reset geometry system state */
  reset(): void;

  /** Unbind current geometry */
  unbind(): void;

  /**
   * Draw bound geometry
   * @param type - Primitive type (TRIANGLES, etc.)
   * @param size - Number of elements to draw
   * @param start - Starting element index
   * @param instanceCount - Number of instances
   */
  draw(type: DRAW_MODES, size?: number, start?: number, instanceCount?: number): void;

  /** Destroy geometry system */
  destroy(): void;
}

/**
 * StateSystem tracks WebGL state changes for optimization
 * Minimizes redundant state changes and GPU overhead  
 */
class StateSystem implements ISystem {
  /** Active state object */
  stateId: number;
  /** Polygon offset state */
  polygonOffset: number;
  /** Current blend mode */  
  blendMode: BLEND_MODES;
  /** Whether state is dirty */
  _blendEq: boolean;

  constructor(renderer: Renderer);

  /**
   * Set WebGL state
   * @param state - State object to apply
   */
  setState(state: State): void;

  /**
   * Set blend mode
   * @param value - Blend mode to apply
   */
  setBlendMode(value: BLEND_MODES): void;

  /**
   * Set polygon offset
   * @param value - Polygon offset value
   * @param scale - Polygon offset scale
   */
  setOffset(value: number, scale: number): void;

  /** Reset state to defaults */
  reset(): void;

  /** Destroy state system */
  destroy(): void;
}

/**
 * BufferSystem manages WebGL buffer objects
 * Handles vertex and index buffer creation and updates
 */
class BufferSystem implements ISystem {
  /** Manages VAO state */
  managedBuffers: {[key: number]: Buffer};
  /** Bound buffer cache */
  boundBufferBases: {[key: number]: Buffer};

  constructor(renderer: Renderer);

  /**
   * Bind buffer to WebGL context
   * @param buffer - Buffer to bind
   */
  bind(buffer: Buffer): void;

  /**
   * Update buffer data
   * @param buffer - Buffer to update
   */
  update(buffer: Buffer): void;

  /** Dispose of buffer resources */
  dispose(buffer: Buffer, contextLost?: boolean): void;

  /** Dispose all managed buffers */
  disposeAll(contextLost?: boolean): void;

  /** Destroy buffer system */
  destroy(): void;
}

import { Renderer } from "@pixi/core";

// Access systems through renderer
const renderer = new Renderer();

// Use texture system
renderer.texture.bind(myTexture, 0); // Bind to texture unit 0
renderer.texture.bind(normalMap, 1);  // Bind to texture unit 1

// Use geometry system  
renderer.geometry.bind(myGeometry, myShader);
renderer.geometry.draw(DRAW_MODES.TRIANGLES, geometry.getSize());

// Use state system
const state = new State();
state.blendMode = BLEND_MODES.ADD;
renderer.state.setState(state);

// Use mask system
const maskData = new MaskData(maskSprite);
renderer.mask.push(maskedObject, maskData);
// ... render masked content ...
renderer.mask.pop(maskedObject);

// Use buffer system (usually automatic)
const buffer = new Buffer(vertexData);
renderer.buffer.update(buffer); // Upload to GPU

// Use framebuffer system
const framebuffer = new Framebuffer(256, 256);
renderer.framebuffer.bind(framebuffer);
// ... render to framebuffer ...
renderer.framebuffer.bind(null); // Bind default framebuffer

// Systems work together for complete rendering
function renderMaskedSprite(sprite, mask) {
  // 1. Set up mask
  const maskData = new MaskData(mask);
  renderer.mask.push(sprite, maskData);
  
  // 2. Bind texture
  renderer.texture.bind(sprite.texture);
  
  // 3. Set blend state
  const state = State.for2d();
  state.blendMode = sprite.blendMode;
  renderer.state.setState(state);
  
  // 4. Bind geometry
  renderer.geometry.bind(sprite.geometry, sprite.shader);
  
  // 5. Draw
  renderer.geometry.draw(DRAW_MODES.TRIANGLES);
  
  // 6. Clean up mask
  renderer.mask.pop(sprite);
}

enum DRAW_MODES {
  POINTS = 0,
  LINES = 1,
  LINE_LOOP = 2,
  LINE_STRIP = 3,
  TRIANGLES = 4,
  TRIANGLE_STRIP = 5,
  TRIANGLE_FAN = 6
}

interface MaskData {
  type: MASK_TYPES;
  autoDetect: boolean;
  maskObject: IRenderableObject;
  pooled: boolean;
  isMaskData: boolean;
  resolution: number;
  multisample: MSAA_QUALITY;
  enabled: boolean;
  colorMask: number;
}

enum MASK_TYPES {
  NONE = 0,
  SCISSOR = 1,
  STENCIL = 2,
  SPRITE = 3,
  COLOR = 4
}