const vs_src = `
	attribute vec4 position;

	uniform mat4 mv_matrix;
	uniform mat4 projection_matrix;

	void main() {
		gl_Position = projection_matrix * mv_matrix * position;
	}
`;

const fs_src = `
	void main() {
		gl_FragColor = vec4(1.0, 1.0, 1.0, 1.0);
	}
`;

export function init(gl) {
	const vshader = loadShader(gl, gl.VERTEX_SHADER, vs_src);
	const fshader = loadShader(gl, gl.FRAGMENT_SHADER, fs_src);

	const program = gl.createProgram();
	gl.attachShader(program, vshader);
	gl.attachShader(program, fshader);

	gl.linkProgram(program);

	if(!gl.getProgramParameter(program, gl.LINK_STATUS)) {
		alert("Unable to initialize shader program: " + gl.getProgramInfoLog(program));
		return null;
	}

	return program;
}

export function loadShader(gl, type, src){
	const shader = gl.createShader(type)

	gl.shaderSource(shader, src);
	gl.compileShader(shader);

	if(!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
		alert('Failed to compile shader : ' + gl.getShaderInfoLog(shader));
		gl.deleteShader(shader);
		return null;
	}

	return shader;
}