import { CompareFunction, Engine, Material, Shader } from "oasis-engine";

export class BgMaterialAndroid extends Material {
  constructor(engine: Engine) {
    const yuv_vs = `
    attribute vec3 POSITION;
    attribute vec2 TEXCOORD_0;
    
    uniform mat4 u_proMatrix;
    varying vec2 v_uv;
    
    void main() {
      v_uv = TEXCOORD_0;
      vec4 position =  u_proMatrix * vec4(POSITION.xy, 1.0, 1.0);
      position.z = position.w;
      gl_Position = position;
    }
    `;

    const yuv_fs = `
    uniform sampler2D u_frameY;
    uniform sampler2D u_frameUV;
    varying vec2 v_uv;

    void main() {
      vec2 cbcr = texture2D(u_frameUV, v_uv).ar - vec2(0.5, 0.5);
      vec3 ycbcr = vec3(texture2D(u_frameY, v_uv).a, cbcr);
      vec3 rgb = mat3(1, 1, 1, 0, -0.344, 1.772, 1.402, -0.714, 0) * ycbcr;
      //vec3 rgb = vec3(1.402 * ycbcr.r, 1.402 * ycbcr.r, 1.402 * ycbcr.r);
      gl_FragColor = vec4(rgb, 1.0);
    }`;

    const shader = Shader.create("ar-background", yuv_vs, yuv_fs);
    super(engine, shader);
    this.renderState.depthState.compareFunction = CompareFunction.LessEqual;
  }
}