"use strict" ;

let gl;
let viewLoc;
let program;
let objects = [];
let posLoc,
	colorLoc;
let lastTimestamp;

let modelViewProjection;
let modelMatrix;
let viewMatrix;
let projectionMatrix;

function main() {

	// Get canvas and setup WebGL context
	const canvas = document.getElementById("gl-canvas");
	gl = canvas.getContext('webgl2');

	// Configure viewport
	gl.viewport(0,0,canvas.width,canvas.height);
	gl.clearColor(1.0,1.0,1.0,1.0);

	gl.enable(gl.DEPTH_TEST);

	// Init shader program via additional function and bind it
	program = initShaders(gl, "vertex-shader", "fragment-shader");
	gl.useProgram(program);

	// Get locations of shader variables
	posLoc = gl.getAttribLocation(program, "vPosition");
	colorLoc = gl.getAttribLocation(program, "vColor");

	// Create object instances
	let island = new Island();
	objects.push(island);

	let river = new River();
	objects.push(river);

	// View Matrix
	var mat = new Float32Array([
		 0.1767766922712326, -0.0589255653321743, -0.013334667310118675, 0,
		 0,                   0.2357022613286972, -0.006667333655059338, 0,
		-0.1767766922712326, -0.0589255653321743, -0.013334667310118675, 0,
		 0,                   0,                  -0.8801880478858948,   1
		]);
	viewLoc = gl.getUniformLocation(program,"viewMatrix");
	gl.uniformMatrix4fv(viewLoc,false,mat);

	viewMatrix = glMatrix.mat4.create();
	projectionMatrix = glMatrix.mat4.create();
	modelViewProjection = glMatrix.mat4.create();
	glMatrix.mat4.perspective(projectionMatrix, 90.0, 1.0, 0.0001, 1000.0)

	glMatrix.mat4.lookAt(viewMatrix, glMatrix.vec3.create(0.8, 0.8, 0.8), glMatrix.vec3.create(0, 0, 0), glMatrix.vec3.create(0, 1, 0))

	window.requestAnimationFrame(render);
};

function render(timestamp) {

	// Only clear once
	gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);

	if (lastTimestamp == undefined) {
		lastTimestamp = timestamp;
	}

	const elapsed = timestamp - lastTimestamp;

	// Call render function of each scene object
	// and don't mix up "of" and "in" up here, both keywords
	// are valid but have different meanings
	for(let object of objects) {
		object.Render();
	};
	window.requestAnimationFrame(render);
}

main();