46 lines
1.2 KiB
TypeScript
46 lines
1.2 KiB
TypeScript
import Program from './program';
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export class FragmentShaderOnlyProgram extends Program {
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private vao?: WebGLVertexArrayObject;
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constructor(
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gl: WebGL2RenderingContext,
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sources: [string, string],
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substitutions: { [name: string]: string }
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) {
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super(gl, sources, substitutions);
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this.prepareScreenQuad('vertexPosition');
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}
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public bind() {
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super.bind();
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this.gl.bindVertexArray(this.vao!);
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}
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public draw() {
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this.gl.drawArrays(this.gl.TRIANGLE_STRIP, 0, 4);
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}
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private prepareScreenQuad(attributeName: string) {
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const positionAttributeLocation = this.gl.getAttribLocation(
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this.program!,
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attributeName
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);
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const positionBuffer = this.gl.createBuffer();
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this.gl.bindBuffer(this.gl.ARRAY_BUFFER, positionBuffer);
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this.gl.bufferData(
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this.gl.ARRAY_BUFFER,
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new Float32Array([-1.0, -1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0]),
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this.gl.STATIC_DRAW
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);
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// can only return null on lost context
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this.vao = this.gl.createVertexArray()!;
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this.gl.bindVertexArray(this.vao);
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this.gl.enableVertexAttribArray(positionAttributeLocation);
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this.gl.vertexAttribPointer(positionAttributeLocation, 2, this.gl.FLOAT, false, 0, 0);
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}
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}
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