//index82
window.addEventListener('resize', onWindowResize, false);
function onWindowResize() {
canvas.width = multiplier * window.innerWidth;
canvas.height = multiplier * window.innerHeight;
gl.viewport(0, 0, canvas.width, canvas.height);
gl.uniform2fv(resolutionHandle, [canvas.width, canvas.height]);
}
function compileShader(shaderSource, shaderType) {
let shader = gl.createShader(shaderType);
gl.shaderSource(shader, shaderSource);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
console.error("Shader compile failed with: " + gl.getShaderInfoLog(shader));
}
return shader;
}
function getAttribLocation(program, name) {
let attributeLocation = gl.getAttribLocation(program, name);
if (attributeLocation == -1) {
console.error("Cannot find attribute <", name, ">.", "Unused variables are optimised out.");
}
return attributeLocation;
}
function getUniformLocation(program, name) {
let uniformLocation = gl.getUniformLocation(program, name);
if (uniformLocation == null) {
console.error("Cannot find uniform <", name, ">.", "Unused variables are optimised out.");
}
return uniformLocation;
}
// shaders
let vertexShader = compileShader(vertexSource, gl.VERTEX_SHADER);
let fragmentShader = compileShader(fragmentSource, gl.FRAGMENT_SHADER);
let program = gl.createProgram();
gl.attachShader(program, vertexShader);
gl.attachShader(program, fragmentShader);
gl.linkProgram(program);
gl.useProgram(program);
let vertexData = new Float32Array([
-1.0, 1.0, // top left
-1.0, -1.0, // bottom left
1.0, 1.0, // top right
1.0, -1.0, // bottom right
]);
let vertexDataBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, vertexDataBuffer);
gl.bufferData(gl.ARRAY_BUFFER, vertexData, gl.STATIC_DRAW);
let positionHandle = getAttribLocation(program, 'position');
gl.enableVertexAttribArray(positionHandle);
gl.vertexAttribPointer(positionHandle, 2, gl.FLOAT, false, 0, 0);
let timeHandle = getUniformLocation(program, "time");
let resolutionHandle = getUniformLocation(program, "resolution");
let sceneHandle = getUniformLocation(program, "u_scene");
let paletteHandle = getUniformLocation(program, "u_palette");
onWindowResize();
gl.uniform1f(sceneHandle, scene);
gl.uniform1f(paletteHandle, palette);
function setScene(name) {
switch (name) {
case "Circle":
scene = 0;
break;
case "Heart":
scene = 1;
break;
case "Star":
scene = 2;
break;
default:
scene = 3;
}
}
function setPalette(name) {
switch (name) {
case "Grayscale":
palette = 0;
break;
case "Rainbow":
palette = 1;
break;
case "Red":
palette = 2;
break;
default:
palette = 3;
}
}
let lastFrame = Date.now();
let thisFrame;
function draw() {
thisFrame = Date.now();
time += (thisFrame - lastFrame) / 1000.0;
lastFrame = thisFrame;
gl.uniform1f(timeHandle, time);
gl.uniform1f(sceneHandle, scene);
gl.uniform1f(paletteHandle, palette);
gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);
requestAnimationFrame(draw);
}
draw();