webgl-fundamentals/webgl/webgl-2d-geometry-rotation.html at master · gfxfundamentals/webgl-fundamentals · GitHub

Name: webgl-fundamentals/webgl/webgl-2d-geometry-rotation.html at master · gfxfundamentals/webgl-fundamentals · GitHub
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<!-- Licensed under a BSD license. See license.html for license -->
<!DOCTYPE html>
<html>
<head>
<metacharset="utf-8">
<metaname="viewport" content="width=device-width, initial-scale=1.0, user-scalable=yes">
<title>WebGL - 2D Geometry Rotation</title>
<linktype="text/css" href="resources/css/ui-lightness/jquery-ui-1.8.16.custom.css" rel="stylesheet" />
<linktype="text/css" href="resources/webgl-tutorials.css" rel="stylesheet" />
</head>
<body>
<divclass="description">
Drag sliders to translate.<br/>
Drag circle to rotate.
</div>
<canvasid="canvas"></canvas>
<divid="uiContainer">
<divid="ui">
<divid="x"></div>
<divid="y"></div>
<divid="rotation"></div>
</div>
</div>
</body>
<scriptsrc="resources/jquery-1.7.1.min.js"></script>
<scriptsrc="resources/jquery-ui-1.8.16.custom.min.js"></script>
<scriptsrc="resources/jquery.mousecapture.js"></script>
<scriptsrc="resources/jquery.gman.ui.js"></script>
<scriptsrc="resources/jquery-gman-circle.js"></script>
<!--
for most samples webgl-utils only provides shader compiling/linking and
canvas resizing because why clutter the examples with code that's the same in every sample.
See https://webglfundamentals.org/webgl/lessons/webgl-boilerplate.html
and https://webglfundamentals.org/webgl/lessons/webgl-resizing-the-canvas.html
for webgl-utils, m3, m4, and webgl-lessons-ui.
-->
<scriptsrc="resources/webgl-utils.js"></script>
<scriptsrc="resources/webgl-lessons-ui.js"></script>
<script>
"use strict";

functionmain(){
// Get A WebGL context
/** @type {HTMLCanvasElement} */
varcanvas=document.querySelector("#canvas");
vargl=canvas.getContext("webgl");
if(!gl){
return;
}

// setup GLSL program
varprogram=webglUtils.createProgramFromScripts(gl,["vertex-shader-2d","fragment-shader-2d"]);

// look up where the vertex data needs to go.
varpositionLocation=gl.getAttribLocation(program,"a_position");

// lookup uniforms
varresolutionLocation=gl.getUniformLocation(program,"u_resolution");
varcolorLocation=gl.getUniformLocation(program,"u_color");
vartranslationLocation=gl.getUniformLocation(program,"u_translation");
varrotationLocation=gl.getUniformLocation(program,"u_rotation");

// Create a buffer to put positions in
varpositionBuffer=gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER,positionBuffer);
// Put geometry data into buffer
setGeometry(gl);

vartranslation=[100,150];
varrotation=[0,1];
varcolor=[Math.random(),Math.random(),Math.random(),1];

drawScene();

// Setup a ui.
webglLessonsUI.setupSlider("#x",{value: translation[0],slide: updatePosition(0),max: gl.canvas.width});
webglLessonsUI.setupSlider("#y",{value: translation[1],slide: updatePosition(1),max: gl.canvas.height});
$("#rotation").gmanUnitCircle({
width: 200,
height: 200,
value: 0,
slide: function(e,u){
rotation[0]=u.x;
rotation[1]=u.y;
drawScene();
}
});

functionupdatePosition(index){
returnfunction(event,ui){
translation[index]=ui.value;
drawScene();
};
}

// Draw the scene.
functiondrawScene(){
webglUtils.resizeCanvasToDisplaySize(gl.canvas);

// Tell WebGL how to convert from clip space to pixels
gl.viewport(0,0,gl.canvas.width,gl.canvas.height);

// Clear the canvas.
gl.clear(gl.COLOR_BUFFER_BIT);

// Tell it to use our program (pair of shaders)
gl.useProgram(program);

// Turn on the attribute
gl.enableVertexAttribArray(positionLocation);

// Bind the position buffer.
gl.bindBuffer(gl.ARRAY_BUFFER,positionBuffer);

// Tell the attribute how to get data out of positionBuffer (ARRAY_BUFFER)
varsize=2;// 2 components per iteration
vartype=gl.FLOAT;// the data is 32bit floats
varnormalize=false;// don't normalize the data
varstride=0;// 0 = move forward size * sizeof(type) each iteration to get the next position
varoffset=0;// start at the beginning of the buffer
gl.vertexAttribPointer(
positionLocation,size,type,normalize,stride,offset);

// set the resolution
gl.uniform2f(resolutionLocation,gl.canvas.width,gl.canvas.height);

// set the color
gl.uniform4fv(colorLocation,color);

// Set the translation.
gl.uniform2fv(translationLocation,translation);

// Set the rotation.
gl.uniform2fv(rotationLocation,rotation);

// Draw the geometry.
varprimitiveType=gl.TRIANGLES;
varoffset=0;
varcount=18;// 6 triangles in the 'F', 3 points per triangle
gl.drawArrays(primitiveType,offset,count);
}
}

// Fill the buffer with the values that define a letter 'F'.
functionsetGeometry(gl){
gl.bufferData(
gl.ARRAY_BUFFER,
newFloat32Array([
// left column
0,0,
30,0,
0,150,
0,150,
30,0,
30,150,

// top rung
30,0,
100,0,
30,30,
30,30,
100,0,
100,30,

// middle rung
30,60,
67,60,
30,90,
30,90,
67,60,
67,90,
]),
gl.STATIC_DRAW);
}

$(function(){
main();
});
</script>
<!-- vertex shader -->
<scriptid="vertex-shader-2d" type="x-shader/x-vertex">
attributevec2a_position;

uniformvec2u_resolution;
uniformvec2u_translation;
uniformvec2u_rotation;

voidmain(){
// Rotate the position
vec2 rotatedPosition =vec2(
a_position.x*u_rotation.y+a_position.y*u_rotation.x,
a_position.y*u_rotation.y-a_position.x*u_rotation.x);

// Add in the translation.
vec2position=rotatedPosition+u_translation;

// convert the position from pixels to 0.0 to 1.0
vec2zeroToOne=position/u_resolution;

// convert from 0->1 to 0->2
vec2zeroToTwo=zeroToOne*2.0;

// convert from 0->2 to -1->+1 (clipspace)
vec2clipSpace=zeroToTwo-1.0;

gl_Position=vec4(clipSpace*vec2(1,-1),0,1);
}
</script>
<!-- fragment shader -->
<scriptid="fragment-shader-2d" type="x-shader/x-fragment">
precisionmediumpfloat;

uniformvec4u_color;

voidmain(){
gl_FragColor=u_color;
}
</script>
</html>