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MinaGabriel/Rotate_Object_Mouse.html

Created November 25, 2020 14:22
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Rotate_Object_Mouse.html
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8"/>
<title>Translate a Triangle</title>
<body onload="main()">
<canvas id="webgl" width="400" height="400">
Please use a browser that supports "canvas"
</canvas>
</body>
<script src="https://rawgit.com/huningxin/webglbook_examples/master/lib/webgl-utils.js"></script>
<script src="https://rawgit.com/huningxin/webglbook_examples/master/lib/webgl-debug.js"></script>
<script src="https://rawgit.com/huningxin/webglbook_examples/master/lib/cuon-utils.js"></script>
<script src="https://rawgit.com/huningxin/webglbook_examples/master/lib/cuon-matrix.js"></script>
<script type="text/javascript">
// RotateObject.js (c) 2012 matsuda and kanda
// Vertex shader program
var VSHADER_SOURCE =
'attribute vec4 a_Position;\n' +
'attribute vec2 a_TexCoord;\n' +
'uniform mat4 u_MvpMatrix;\n' +
'varying vec2 v_TexCoord;\n' +
'void main() {\n' +
' gl_Position = u_MvpMatrix * a_Position;\n' +
' v_TexCoord = a_TexCoord;\n' +
'}\n';
// Fragment shader program
var FSHADER_SOURCE =
'#ifdef GL_ES\n' +
'precision mediump float;\n' +
'#endif\n' +
'uniform sampler2D u_Sampler;\n' +
'varying vec2 v_TexCoord;\n' +
'void main() {\n' +
' gl_FragColor = texture2D(u_Sampler, v_TexCoord);\n' +
'}\n';
function main() {
// Retrieve <canvas> element
var canvas = document.getElementById('webgl');
// Get the rendering context for WebGL
var gl = getWebGLContext(canvas);
if (!gl) {
console.log('Failed to get the rendering context for WebGL');
return;
}
// Initialize shaders
if (!initShaders(gl, VSHADER_SOURCE, FSHADER_SOURCE)) {
console.log('Failed to intialize shaders.');
return;
}
// Set the vertex information
var n = initVertexBuffers(gl);
if (n < 0) {
console.log('Failed to set the vertex information');
return;
}
// Set the clear color and enable the depth test
gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.enable(gl.DEPTH_TEST);
// Get the storage locations of uniform variables
var u_MvpMatrix = gl.getUniformLocation(gl.program, 'u_MvpMatrix');
if (!u_MvpMatrix) {
console.log('Failed to get the storage location of uniform variable');
return;
}
// Calculate the view projection matrix
var viewProjMatrix = new Matrix4();
viewProjMatrix.setPerspective(30.0, canvas.width / canvas.height, 1.0, 100.0);
viewProjMatrix.lookAt(3.0, 3.0, 7.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
// Register the event handler
var currentAngle = [0.0, 0.0]; // Current rotation angle ([x-axis, y-axis] degrees)
initEventHandlers(canvas, currentAngle);
// Set texture
if (!initTextures(gl)) {
console.log('Failed to intialize the texture.');
return;
}
var tick = function() { // Start drawing
draw(gl, n, viewProjMatrix, u_MvpMatrix, currentAngle);
requestAnimationFrame(tick, canvas);
};
tick();
}
function initVertexBuffers(gl) {
// Create a cube
// v6----- v5
// /| /|
// v1------v0|
// | | | |
// | |v7---|-|v4
// |/ |/
// v2------v3
var vertices = new Float32Array([ // Vertex coordinates
1.0, 1.0, 1.0, -1.0, 1.0, 1.0, -1.0,-1.0, 1.0, 1.0,-1.0, 1.0, // v0-v1-v2-v3 front
1.0, 1.0, 1.0, 1.0,-1.0, 1.0, 1.0,-1.0,-1.0, 1.0, 1.0,-1.0, // v0-v3-v4-v5 right
1.0, 1.0, 1.0, 1.0, 1.0,-1.0, -1.0, 1.0,-1.0, -1.0, 1.0, 1.0, // v0-v5-v6-v1 up
-1.0, 1.0, 1.0, -1.0, 1.0,-1.0, -1.0,-1.0,-1.0, -1.0,-1.0, 1.0, // v1-v6-v7-v2 left
-1.0,-1.0,-1.0, 1.0,-1.0,-1.0, 1.0,-1.0, 1.0, -1.0,-1.0, 1.0, // v7-v4-v3-v2 down
1.0,-1.0,-1.0, -1.0,-1.0,-1.0, -1.0, 1.0,-1.0, 1.0, 1.0,-1.0 // v4-v7-v6-v5 back
]);
var texCoords = new Float32Array([ // Texture coordinates
1.0, 1.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, // v0-v1-v2-v3 front
0.0, 1.0, 0.0, 0.0, 1.0, 0.0, 1.0, 1.0, // v0-v3-v4-v5 right
1.0, 0.0, 1.0, 1.0, 0.0, 1.0, 0.0, 0.0, // v0-v5-v6-v1 up
1.0, 1.0, 0.0, 1.0, 0.0, 0.0, 1.0, 0.0, // v1-v6-v7-v2 left
0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0, // v7-v4-v3-v2 down
0.0, 0.0, 1.0, 0.0, 1.0, 1.0, 0.0, 1.0 // v4-v7-v6-v5 back
]);
// Indices of the vertices
var indices = new Uint8Array([
0, 1, 2, 0, 2, 3, // front
4, 5, 6, 4, 6, 7, // right
8, 9,10, 8,10,11, // up
12,13,14, 12,14,15, // left
16,17,18, 16,18,19, // down
20,21,22, 20,22,23 // back
]);
// Create a buffer object
var indexBuffer = gl.createBuffer();
if (!indexBuffer) {
return -1;
}
// Write vertex information to buffer object
if (!initArrayBuffer(gl, vertices, 3, gl.FLOAT, 'a_Position')) return -1; // Vertex coordinates
if (!initArrayBuffer(gl, texCoords, 2, gl.FLOAT, 'a_TexCoord')) return -1;// Texture coordinates
// Unbind the buffer object
gl.bindBuffer(gl.ARRAY_BUFFER, null);
// Write the indices to the buffer object
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, indices, gl.STATIC_DRAW);
return indices.length;
}
function initEventHandlers(canvas, currentAngle) {
var dragging = false; // Dragging or not
var lastX = -1, lastY = -1; // Last position of the mouse
canvas.onmousedown = function(ev) { // Mouse is pressed
var x = ev.clientX, y = ev.clientY;
// Start dragging if a moue is in <canvas>
var rect = ev.target.getBoundingClientRect();
if (rect.left <= x && x < rect.right && rect.top <= y && y < rect.bottom) {
lastX = x; lastY = y;
dragging = true;
}
};
canvas.onmouseup = function(ev) { dragging = false; }; // Mouse is released
canvas.onmousemove = function(ev) { // Mouse is moved
var x = ev.clientX, y = ev.clientY;
if (dragging) {
var factor = 100/canvas.height; // The rotation ratio
var dx = factor * (x - lastX);
var dy = factor * (y - lastY);
// Limit x-axis rotation angle to -90 to 90 degrees
currentAngle[0] = Math.max(Math.min(currentAngle[0] + dy, 90.0), -90.0);
currentAngle[1] = currentAngle[1] + dx;
}
lastX = x, lastY = y;
};
}
var g_MvpMatrix = new Matrix4(); // Model view projection matrix
function draw(gl, n, viewProjMatrix, u_MvpMatrix, currentAngle) {
// Caliculate The model view projection matrix and pass it to u_MvpMatrix
g_MvpMatrix.set(viewProjMatrix);
g_MvpMatrix.rotate(currentAngle[0], 1.0, 0.0, 0.0); // Rotation around x-axis
g_MvpMatrix.rotate(currentAngle[1], 0.0, 1.0, 0.0); // Rotation around y-axis
gl.uniformMatrix4fv(u_MvpMatrix, false, g_MvpMatrix.elements);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); // Clear buffers
gl.drawElements(gl.TRIANGLES, n, gl.UNSIGNED_BYTE, 0); // Draw the cube
}
function initArrayBuffer(gl, data, num, type, attribute) {
// Create a buffer object
var buffer = gl.createBuffer();
if (!buffer) {
console.log('Failed to create the buffer object');
return false;
}
// Write date into the buffer object
gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
gl.bufferData(gl.ARRAY_BUFFER, data, gl.STATIC_DRAW);
// Assign the buffer object to the attribute variable
var a_attribute = gl.getAttribLocation(gl.program, attribute);
if (a_attribute < 0) {
console.log('Failed to get the storage location of ' + attribute);
return false;
}
gl.vertexAttribPointer(a_attribute, num, type, false, 0, 0);
// Enable the assignment to a_attribute variable
gl.enableVertexAttribArray(a_attribute);
return true;
}
function initTextures(gl) {
// Create a texture object
var texture = gl.createTexture();
if (!texture) {
console.log('Failed to create the texture object');
return false;
}
// Get the storage location of u_Sampler
var u_Sampler = gl.getUniformLocation(gl.program, 'u_Sampler');
if (!u_Sampler) {
console.log('Failed to get the storage location of u_Sampler');
return false;
}
// Create the image object
var image = new Image();
if (!image) {
console.log('Failed to create the image object');
return false;
}
// Register the event handler to be called when image loading is completed
image.onload = function(){ loadTexture(gl, texture, u_Sampler, image); };
// Tell the browser to load an Image
image.src = 'webglbook_examples/resources/sky.JPG';
return true;
}
function loadTexture(gl, texture, u_Sampler, image) {
gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, 1); // Flip the image Y coordinate
// Activate texture unit0
gl.activeTexture(gl.TEXTURE0);
// Bind the texture object to the target
gl.bindTexture(gl.TEXTURE_2D, texture);
// Set texture parameters
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
// Set the image to texture
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGB, gl.RGB, gl.UNSIGNED_BYTE, image);
// Pass the texure unit 0 to u_Sampler
gl.uniform1i(u_Sampler, 0);
}
</script>
</head>
</html>
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