//
//  initShaders.js
//

function initShaders(gl, vertexShaderId, fragmentShaderId) {
	const compileShader = (gl, gl_shaderType, shaderSource) => {
		// Create the shader
		shader = gl.createShader(gl_shaderType);

		// Set the shader source code
		gl.shaderSource(shader, shaderSource);

		// Compile the shader to make it readable for the GPU
		gl.compileShader(shader);
		var success = gl.getShaderParameter(shader, gl.COMPILE_STATUS);

		if (!success) {
			// Something went wrong during compilation; get the error
			throw "could not compile shader:" + gl.getShaderInfoLog(shader);
		} else {
			return shader;
		}
	};

	/*
	 * Setup shader program
	 */
	vShaderSource = document.querySelector("#" + vertexShaderId).text;
	fShaderSource = document.querySelector("#" + fragmentShaderId).text;

	vertexShader = compileShader(gl, gl.VERTEX_SHADER, vShaderSource);
	fragmentShader = compileShader(gl, gl.FRAGMENT_SHADER, fShaderSource);

	// Build the program
	const program = gl.createProgram();

	// Attach shaders to it
	gl.attachShader(program, vertexShader);
	gl.attachShader(program, fragmentShader);

	gl.linkProgram(program);

	return program;
}