Add files

src/graphics/graphics-library/program/fragment-shader-only-program.ts

@@ -0,0 +1,52 @@
+import Program from './program';
+
+export class FragmentShaderOnlyProgram extends Program {
+  private vao?: WebGLVertexArrayObject;
+
+  constructor(
+    gl: WebGL2RenderingContext,
+    sources: [string, string],
+    substitutions: { [name: string]: string }
+  ) {
+    super(gl, sources, substitutions);
+  }
+
+  public async initialize(): Promise<void> {
+    await super.initialize();
+    this.prepareScreenQuad('vertexPosition');
+  }
+
+  public bind() {
+    super.bind();
+    this.gl.bindVertexArray(this.vao!);
+  }
+
+  public draw() {
+    this.gl.drawArrays(this.gl.TRIANGLE_STRIP, 0, 4);
+  }
+
+  private prepareScreenQuad(attributeName: string) {
+    const positionAttributeLocation = this.gl.getAttribLocation(
+      this.program!,
+      attributeName
+    );
+
+    const positionBuffer = this.gl.createBuffer();
+
+    this.gl.bindBuffer(this.gl.ARRAY_BUFFER, positionBuffer);
+    this.gl.bufferData(
+      this.gl.ARRAY_BUFFER,
+      new Float32Array([-1.0, -1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0]),
+      this.gl.STATIC_DRAW
+    );
+    const vao = this.gl.createVertexArray();
+    if (!vao) {
+      throw new Error('Could not create vertex array object');
+    }
+    this.vao = vao;
+
+    this.gl.bindVertexArray(this.vao);
+    this.gl.enableVertexAttribArray(positionAttributeLocation);
+    this.gl.vertexAttribPointer(positionAttributeLocation, 2, this.gl.FLOAT, false, 0, 0);
+  }
+}