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blendfunc.html
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blendfunc.html
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<!DOCTYPE HTML>
<html lang="en">
<head>
<title>gl.blendFunc()</title>
<meta charset="utf-8">
<style type="text/css">
body {
font-family: Monospace;
background-color: #ffffff;
margin: 20px;
overflow: hidden;
}
#info {
position: absolute;
top: 0px;
color: #ffffff;
font-size: 14px;
font-weight: bold;
text-shadow: rgba( 0, 0, 0, 0.75 ) 0px 1px 2px;
}
#effect {
width: 400px;
height: 400px;
margin-right: 20px;
background: url("files/bg.png");
float: left;
}
.thumb {
width: 75px;
height: 75px;
margin-bottom: 10px;
background: url("files/bg.png");
}
</style>
</head>
<body>
<div style="position:absolute;top:0px;right:0px;">
<a href="https://github.com/mrdoob/webgl-blendfunctions"><img src="files/fork_me_at_github.png"></a>
</div>
<h1>gl.blendFunc()</h1>
<table><tr valign="top"><td>
<div id="effect"></div>
</td><td>
<strong>Equation<strong><br />
<select id="equation" onkeyup="update();" onchange="update();">
<option selected>FUNC_ADD</option>
<option>FUNC_SUBTRACT</option>
<option>FUNC_REVERSE_SUBTRACT</option>
</select>
<br /><br />
<strong>Source</strong><br />
<div class="thumb"><img id="texture2" width="75" /></div>
<select id="source" onkeyup="update();" onchange="update();">
<option>ZERO</option>
<option>ONE</option>
<option>SRC_COLOR</option>
<option>ONE_MINUS_SRC_COLOR</option>
<option>DST_COLOR</option>
<option>ONE_MINUS_DST_COLOR</option>
<option selected>SRC_ALPHA</option>
<option>ONE_MINUS_SRC_ALPHA</option>
<option>DST_ALPHA</option>
<option>ONE_MINUS_DST_ALPHA</option>
<option>SRC_ALPHA_SATURATE</option>
<option>CONSTANT_COLOR</option>
<option>ONE_MINUS_CONSTANT_COLOR</option>
<option>CONSTANT_ALPHA</option>
<option>ONE_MINUS_CONSTANT_ALPHA</option>
</select>
<br /><br />
<strong>Destination<strong><br />
<div class="thumb"><img id="texture1" width="75" /></div>
<select id="destination" onkeyup="update();" onchange="update();">
<option>ZERO</option>
<option>ONE</option>
<option>SRC_COLOR</option>
<option>ONE_MINUS_SRC_COLOR</option>
<option>DST_COLOR</option>
<option>ONE_MINUS_DST_COLOR</option>
<option>SRC_ALPHA</option>
<option selected>ONE_MINUS_SRC_ALPHA</option>
<option>DST_ALPHA</option>
<option>ONE_MINUS_DST_ALPHA</option>
<option>SRC_ALPHA_SATURATE</option>
<option>CONSTANT_COLOR</option>
<option>ONE_MINUS_CONSTANT_COLOR</option>
<option>CONSTANT_ALPHA</option>
<option>ONE_MINUS_CONSTANT_ALPHA</option>
</select>
<br /><br />
</td></tr></table>
<br />
<textarea id="code" style="width:700px;height:80px;"></textarea>
<script id="vs" type="x-shader/x-vertex">
attribute vec3 position;
void main() {
gl_Position = vec4( position, 1.0 );
}
</script>
<script id="fs" type="x-shader/x-fragment">
uniform vec2 resolution;
uniform sampler2D texture;
void main( void ) {
gl_FragColor = texture2D( texture, gl_FragCoord.xy / resolution.xy ).rgba;
}
</script>
<script type="text/javascript">
var effectDiv, sourceDiv, canvas, gl, buffer,
vertex_shader, fragment_shader, currentProgram,
vertexPositionLocation, texture1, texture2, textureLocation,
parameters = { screenWidth: 0, screenHeight: 0 },
equations, functions;
init();
function init() {
vertex_shader = document.getElementById( 'vs' ).textContent;
fragment_shader = document.getElementById( 'fs' ).textContent;
effectDiv = document.getElementById( 'effect' );
canvas = document.createElement( 'canvas' );
effectDiv.appendChild( canvas );
// Initialise WebGL
try {
gl = canvas.getContext( 'experimental-webgl', { premultipliedAlpha: false } );
gl.enable( gl.DEPTH_TEST );
gl.depthFunc( gl.LEQUAL );
gl.enable( gl.BLEND );
gl.pixelStorei( gl.UNPACK_FLIP_Y_WEBGL, true );
} catch( error ) { }
if ( !gl ) {
alert("WebGL not supported");
throw "cannot create webgl context";
}
equations = [
"gl.FUNC_ADD",
"gl.FUNC_SUBTRACT",
"gl.FUNC_REVERSE_SUBTRACT"
];
functions = [
"gl.ZERO",
"gl.ONE",
"gl.SRC_COLOR",
"gl.ONE_MINUS_SRC_COLOR",
"gl.DST_COLOR",
"gl.ONE_MINUS_DST_COLOR",
"gl.SRC_ALPHA",
"gl.ONE_MINUS_SRC_ALPHA",
"gl.DST_ALPHA",
"gl.ONE_MINUS_DST_ALPHA",
"gl.SRC_ALPHA_SATURATE",
"gl.CONSTANT_COLOR",
"gl.ONE_MINUS_CONSTANT_COLOR",
"gl.CONSTANT_ALPHA",
"gl.ONE_MINUS_CONSTANT_ALPHA"
];
// Create Vertex buffer (2 triangles)
buffer = gl.createBuffer();
gl.bindBuffer( gl.ARRAY_BUFFER, buffer );
gl.bufferData( gl.ARRAY_BUFFER, new Float32Array( [
- 1.0, - 1.0, 1.0,
- 1.0, - 1.0, 1.0,
1.0, - 1.0, 1.0,
1.0, - 1.0, 1.0
] ), gl.STATIC_DRAW );
// Create Program
currentProgram = createProgram( vertex_shader, fragment_shader );
document.getElementById( 'texture1' ).src = 'files/dst.png';
texture1 = loadTexture( 'files/dst.png' );
document.getElementById( 'texture2' ).src = 'files/src.png';
texture2 = loadTexture( 'files/src.png' );
onWindowResize();
window.addEventListener( 'resize', onWindowResize, false );
}
function onWindowResize( event ) {
canvas.width = 400;
canvas.height = 400;
parameters.screenWidth = canvas.width;
parameters.screenHeight = canvas.height;
gl.viewport( 0, 0, canvas.width, canvas.height );
}
function loadTexture( path ) {
var texture = gl.createTexture();
var image = new Image();
image.onload = function() {
gl.enable( gl.TEXTURE_2D );
gl.bindTexture( gl.TEXTURE_2D, texture );
gl.texImage2D( gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, image );
gl.texParameteri( gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR );
gl.texParameteri( gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR );
gl.texParameteri( gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE );
gl.texParameteri( gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE );
gl.generateMipmap( gl.TEXTURE_2D );
gl.bindTexture( gl.TEXTURE_2D, null );
update();
};
image.src = path;
return texture;
}
function createProgram( vertex, fragment ) {
var program = gl.createProgram();
var vs = createShader( vertex, gl.VERTEX_SHADER );
var fs = createShader( '#ifdef GL_ES\nprecision highp float;\n#endif\n\n' + fragment, gl.FRAGMENT_SHADER );
if ( vs == null || fs == null ) return null;
gl.attachShader( program, vs );
gl.attachShader( program, fs );
gl.deleteShader( vs );
gl.deleteShader( fs );
gl.linkProgram( program );
if ( !gl.getProgramParameter( program, gl.LINK_STATUS ) ) {
alert( "ERROR:\n" +
"VALIDATE_STATUS: " + gl.getProgramParameter( program, gl.VALIDATE_STATUS ) + "\n" +
"ERROR: " + gl.getError() + "\n\n" +
"- Vertex Shader -\n" + vertex + "\n\n" +
"- Fragment Shader -\n" + fragment );
return null;
}
return program;
}
function createShader( src, type ) {
var shader = gl.createShader( type );
gl.shaderSource( shader, src );
gl.compileShader( shader );
if ( !gl.getShaderParameter( shader, gl.COMPILE_STATUS ) ) {
alert( ( type == gl.VERTEX_SHADER ? "VERTEX" : "FRAGMENT" ) + " SHADER:\n" + gl.getShaderInfoLog( shader ) );
return null;
}
return shader;
}
function update() {
var textarea = document.getElementById( 'code' );
textarea.innerHTML = "gl.enable( gl.BLEND );\ngl.blendEquation( " + equations[ document.getElementById( 'equation' ).selectedIndex ] + " );\ngl.blendFunc( " + functions[ document.getElementById( 'source' ).selectedIndex ] + ", " + functions[ document.getElementById( 'destination' ).selectedIndex ] + " );";
render();
}
function render() {
if ( !currentProgram ) return;
gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );
// Load program into GPU
gl.useProgram( currentProgram );
// Get var locations
vertexPositionLocation = gl.getAttribLocation( currentProgram, 'position' );
textureLocation = gl.getUniformLocation( currentProgram, 'texture' );
// Set values to program variables
gl.uniform2f( gl.getUniformLocation( currentProgram, 'resolution' ), parameters.screenWidth, parameters.screenHeight );
gl.uniform1i( textureLocation, 0 );
gl.activeTexture( gl.TEXTURE0 );
gl.bindTexture( gl.TEXTURE_2D, texture1 );
// disable blending for simple output of the texture
gl.disable(gl.BLEND);
// Render geometry
gl.bindBuffer( gl.ARRAY_BUFFER, buffer );
gl.vertexAttribPointer( vertexPositionLocation, 2, gl.FLOAT, false, 0, 0 );
gl.enableVertexAttribArray( vertexPositionLocation );
gl.drawArrays( gl.TRIANGLES, 0, 6 );
gl.disableVertexAttribArray( vertexPositionLocation );
// set custom blend mode
gl.enable(gl.BLEND);
gl.blendEquation(
eval( equations[ document.getElementById( 'equation' ).selectedIndex ] )
);
gl.blendFunc(
eval( functions[ document.getElementById( 'source' ).selectedIndex ] ),
eval( functions[ document.getElementById( 'destination' ).selectedIndex ] )
);
gl.bindTexture( gl.TEXTURE_2D, texture2 );
// Render geometry
gl.bindBuffer( gl.ARRAY_BUFFER, buffer );
gl.vertexAttribPointer( vertexPositionLocation, 2, gl.FLOAT, false, 0, 0 );
gl.enableVertexAttribArray( vertexPositionLocation );
gl.drawArrays( gl.TRIANGLES, 0, 6 );
gl.disableVertexAttribArray( vertexPositionLocation );
}
</script>
</body>
</html>