How to get a "Glow" shader effect in OpenGL ES 2.0?
46,888
Solution 1
First of all there are tons of algorithms and techniques to generate a glow effect. I just want to present one possibility.
Create a Material that is luminescent. For this I use a modified Blinn-Phong light model, where the direction to the light source is always the inverse direction of the normal vector of the fragment.
varying vec3 vertPos;
varying vec3 vertNV;
varying vec3 vertCol;
uniform float u_glow;
void main()
{
vec3 color = vertCol;
float shininess = 10.0;
vec3 normalV = normalize( vertNV );
vec3 eyeV = normalize( -vertPos );
vec3 halfV = normalize( eyeV + normalV );
float NdotH = max( 0.0, dot( normalV, halfV ) );
float glowFac = ( shininess + 2.0 ) * pow( NdotH, shininess ) / ( 2.0 * 3.14159265 );
gl_FragColor = vec4( u_glow * (0.1 + color.rgb * glowFac * 0.5), 1.0 );
}
In a second step a gaussian blur algorithm is performed on the output. The scene is written to frame buffer with a texture bound to the color plane. A screen space pass uses the texture as the input to blur the output.
For performance reasons, the blur algorithm is first performed along the X-axis of the viewport and in a further step along the Y-axis of the viewport.
varying vec2 vertPos;
uniform sampler2D u_textureCol;
uniform vec2 u_textureSize;
uniform float u_sigma;
uniform int u_width;
float CalcGauss( float x, float sigma )
{
float coeff = 1.0 / (2.0 * 3.14157 * sigma);
float expon = -(x*x) / (2.0 * sigma);
return (coeff*exp(expon));
}
void main()
{
vec2 texC = vertPos.st * 0.5 + 0.5;
vec4 texCol = texture( u_textureCol, texC );
vec4 gaussCol = vec4( texCol.rgb, 1.0 );
vec2 step = 1.0 / u_textureSize;
for ( int i = 1; i <= u_width; ++ i )
{
vec2 actStep = vec2( float(i) * step.x, 0.0 ); // this is for the X-axis
// vec2 actStep = vec2( 0.0, float(i) * step.y ); this would be for the Y-axis
float weight = CalcGauss( float(i) / float(u_width), u_sigma );
texCol = texture2D( u_textureCol, texC + actStep );
gaussCol += vec4( texCol.rgb * weight, weight );
texCol = texture2D( u_textureCol, texC - actStep );
gaussCol += vec4( texCol.rgb * weight, weight );
}
gaussCol.rgb /= gaussCol.w;
gl_FragColor = vec4( gaussCol.rgb, 1.0 );
}
For the implementation of a blur algorithm see also the answer to the questions:
See the following similar WebGL example which puts all together:
var readInput = true;
function changeEventHandler(event){
readInput = true;
}
(function loadscene() {
var resize, gl, progDraw, progBlurX, progPost, vp_size, blurFB;
var bufCube = {};
var bufQuad = {};
var shininess = 10.0;
var glow = 10.0;
var sigma = 0.8;
function render(delteMS){
//if ( readInput ) {
readInput = false;
var sliderScale = 100;
shininess = document.getElementById( "shine" ).value;
glow = document.getElementById( "glow" ).value / sliderScale;
sigma = document.getElementById( "sigma" ).value / sliderScale;
//}
Camera.create();
Camera.vp = vp_size;
gl.enable( gl.DEPTH_TEST );
gl.clearColor( 0.0, 0.0, 0.0, 1.0 );
gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );
// set up framebuffer
gl.bindFramebuffer( gl.FRAMEBUFFER, blurFB[0] );
gl.viewport( 0, 0, blurFB[0].width, blurFB[0].height );
gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );
// set up draw shader
ShaderProgram.Use( progDraw.prog );
ShaderProgram.SetUniformM44( progDraw.prog, "u_projectionMat44", Camera.Perspective() );
ShaderProgram.SetUniformM44( progDraw.prog, "u_viewMat44", Camera.LookAt() );
var modelMat = IdentityMat44()
modelMat = RotateAxis( modelMat, CalcAng( delteMS, 13.0 ), 0 );
modelMat = RotateAxis( modelMat, CalcAng( delteMS, 17.0 ), 1 );
ShaderProgram.SetUniformM44( progDraw.prog, "u_modelMat44", modelMat );
ShaderProgram.SetUniformF1( progDraw.prog, "u_shininess", shininess );
ShaderProgram.SetUniformF1( progDraw.prog, "u_glow", glow );
// draw scene
VertexBuffer.Draw( bufCube );
// set blur-X framebuffer and bind frambuffer texture
gl.bindFramebuffer( gl.FRAMEBUFFER, blurFB[1] );
gl.viewport( 0, 0, blurFB[1].width, blurFB[1].height );
gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );
var texUnit = 1;
gl.activeTexture( gl.TEXTURE0 + texUnit );
gl.bindTexture( gl.TEXTURE_2D, blurFB[0].color0_texture );
// set up blur-X shader
ShaderProgram.Use( progBlurX.prog );
ShaderProgram.SetUniformI1( progBlurX.prog , "u_texture", texUnit )
ShaderProgram.SetUniformF2( progBlurX.prog , "u_textureSize", vp_size );
ShaderProgram.SetUniformF1( progBlurX.prog , "u_sigma", sigma )
// draw full screen space
gl.enableVertexAttribArray( progBlurX.inPos );
gl.bindBuffer( gl.ARRAY_BUFFER, bufQuad.pos );
gl.vertexAttribPointer( progBlurX.inPos, 2, gl.FLOAT, false, 0, 0 );
gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufQuad.inx );
gl.drawElements( gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0 );
gl.disableVertexAttribArray( progBlurX.inPos );
// reset framebuffer and bind frambuffer texture
gl.bindFramebuffer( gl.FRAMEBUFFER, null );
gl.viewport( 0, 0, vp_size[0], vp_size[1] );
gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );
texUnit = 2;
gl.activeTexture( gl.TEXTURE0 + texUnit );
gl.bindTexture( gl.TEXTURE_2D, blurFB[1].color0_texture );
// set up pst process shader
ShaderProgram.Use( progPost.prog );
ShaderProgram.SetUniformI1( progPost.prog, "u_texture", texUnit )
ShaderProgram.SetUniformF2( progPost.prog, "u_textureSize", vp_size );
ShaderProgram.SetUniformF1( progPost.prog, "u_sigma", sigma );
// draw full screen space
gl.enableVertexAttribArray( progPost.inPos );
gl.bindBuffer( gl.ARRAY_BUFFER, bufQuad.pos );
gl.vertexAttribPointer( progPost.inPos, 2, gl.FLOAT, false, 0, 0 );
gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufQuad.inx );
gl.drawElements( gl.TRIANGLES, 6, gl.UNSIGNED_SHORT, 0 );
gl.disableVertexAttribArray( progPost.inPos );
requestAnimationFrame(render);
}
function resize() {
//vp_size = [gl.drawingBufferWidth, gl.drawingBufferHeight];
vp_size = [window.innerWidth, window.innerHeight]
canvas.width = vp_size[0];
canvas.height = vp_size[1];
var fbsize = Math.max(vp_size[0], vp_size[1])-1;
fbsize = 1 << 31 - Math.clz32(fbsize); // nearest power of 2
fbsize = fbsize * 2
blurFB = [];
for ( var i = 0; i < 2; ++ i ) {
fb = gl.createFramebuffer();
fb.width = fbsize;
fb.height = fbsize;
gl.bindFramebuffer( gl.FRAMEBUFFER, fb );
fb.color0_texture = gl.createTexture();
gl.bindTexture( gl.TEXTURE_2D, fb.color0_texture );
gl.texParameteri( gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST );
gl.texParameteri( gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST );
gl.texImage2D( gl.TEXTURE_2D, 0, gl.RGBA, fb.width, fb.height, 0, gl.RGBA, gl.UNSIGNED_BYTE, null );
fb.renderbuffer = gl.createRenderbuffer();
gl.bindRenderbuffer( gl.RENDERBUFFER, fb.renderbuffer );
gl.renderbufferStorage( gl.RENDERBUFFER, gl.DEPTH_COMPONENT16, fb.width, fb.height );
gl.framebufferTexture2D( gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, fb.color0_texture, 0 );
gl.framebufferRenderbuffer( gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, fb.renderbuffer );
gl.bindTexture( gl.TEXTURE_2D, null );
gl.bindRenderbuffer( gl.RENDERBUFFER, null );
gl.bindFramebuffer( gl.FRAMEBUFFER, null );
blurFB.push( fb );
}
}
function initScene() {
canvas = document.getElementById( "canvas");
gl = canvas.getContext( "experimental-webgl" );
if ( !gl )
return null;
progDraw = {}
progDraw.prog = ShaderProgram.Create(
[ { source : "draw-shader-vs", stage : gl.VERTEX_SHADER },
{ source : "draw-shader-fs", stage : gl.FRAGMENT_SHADER }
] );
if ( !progDraw.prog )
return null;
progDraw.inPos = gl.getAttribLocation( progDraw.prog, "inPos" );
progDraw.inNV = gl.getAttribLocation( progDraw.prog, "inNV" );
progDraw.inCol = gl.getAttribLocation( progDraw.prog, "inCol" );
progBlurX = {}
progBlurX.prog = ShaderProgram.Create(
[ { source : "post-shader-vs", stage : gl.VERTEX_SHADER },
{ source : "blurX-shader-fs", stage : gl.FRAGMENT_SHADER }
] );
progBlurX.inPos = gl.getAttribLocation( progBlurX.prog, "inPos" );
if ( !progBlurX.prog )
return;
progPost = {}
progPost.prog = ShaderProgram.Create(
[ { source : "post-shader-vs", stage : gl.VERTEX_SHADER },
{ source : "blurY-shader-fs", stage : gl.FRAGMENT_SHADER }
] );
progPost.inPos = gl.getAttribLocation( progPost.prog, "inPos" );
if ( !progPost.prog )
return;
// create cube
var cubePos = [
-1.0, -1.0, 1.0, 1.0, -1.0, 1.0, 1.0, 1.0, 1.0, -1.0, 1.0, 1.0,
-1.0, -1.0, -1.0, 1.0, -1.0, -1.0, 1.0, 1.0, -1.0, -1.0, 1.0, -1.0 ];
var cubeCol = [ 1.0, 0.0, 0.0, 1.0, 0.5, 0.0, 1.0, 0.0, 1.0, 1.0, 1.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 1.0 ];
var cubeHlpInx = [ 0, 1, 2, 3, 1, 5, 6, 2, 5, 4, 7, 6, 4, 0, 3, 7, 3, 2, 6, 7, 1, 0, 4, 5 ];
var cubePosData = [];
for ( var i = 0; i < cubeHlpInx.length; ++ i ) {
cubePosData.push( cubePos[cubeHlpInx[i]*3], cubePos[cubeHlpInx[i]*3+1], cubePos[cubeHlpInx[i]*3+2] );
}
var cubeNVData = [];
for ( var i1 = 0; i1 < cubeHlpInx.length; i1 += 4 ) {
var nv = [0, 0, 0];
for ( i2 = 0; i2 < 4; ++ i2 ) {
var i = i1 + i2;
nv[0] += cubePosData[i*3]; nv[1] += cubePosData[i*3+1]; nv[2] += cubePosData[i*3+2];
}
for ( i2 = 0; i2 < 4; ++ i2 )
cubeNVData.push( nv[0], nv[1], nv[2] );
}
var cubeColData = [];
for ( var is = 0; is < 6; ++ is ) {
for ( var ip = 0; ip < 4; ++ ip ) {
cubeColData.push( cubeCol[is*3], cubeCol[is*3+1], cubeCol[is*3+2] );
}
}
var cubeInxData = [];
for ( var i = 0; i < cubeHlpInx.length; i += 4 ) {
cubeInxData.push( i, i+1, i+2, i, i+2, i+3 );
}
bufCube = VertexBuffer.Create(
[ { data : cubePosData, attrSize : 3, attrLoc : progDraw.inPos },
{ data : cubeNVData, attrSize : 3, attrLoc : progDraw.inNV },
{ data : cubeColData, attrSize : 3, attrLoc : progDraw.inCol } ],
cubeInxData );
bufQuad.pos = gl.createBuffer();
gl.bindBuffer( gl.ARRAY_BUFFER, bufQuad.pos );
gl.bufferData( gl.ARRAY_BUFFER, new Float32Array( [ -1.0, -1.0, 1.0, -1.0, 1.0, 1.0, -1.0, 1.0 ] ), gl.STATIC_DRAW );
bufQuad.inx = gl.createBuffer();
gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufQuad.inx );
gl.bufferData( gl.ELEMENT_ARRAY_BUFFER, new Uint16Array( [ 0, 1, 2, 0, 2, 3 ] ), gl.STATIC_DRAW );
window.onresize = resize;
resize();
requestAnimationFrame(render);
}
function Fract( val ) {
return val - Math.trunc( val );
}
function CalcAng( deltaTime, intervall ) {
return Fract( deltaTime / (1000*intervall) ) * 2.0 * Math.PI;
}
function CalcMove( deltaTime, intervall, range ) {
var pos = self.Fract( deltaTime / (1000*intervall) ) * 2.0
var pos = pos < 1.0 ? pos : (2.0-pos)
return range[0] + (range[1] - range[0]) * pos;
}
function EllipticalPosition( a, b, angRag ) {
var a_b = a * a - b * b
var ea = (a_b <= 0) ? 0 : Math.sqrt( a_b );
var eb = (a_b >= 0) ? 0 : Math.sqrt( -a_b );
return [ a * Math.sin( angRag ) - ea, b * Math.cos( angRag ) - eb, 0 ];
}
glArrayType = typeof Float32Array !="undefined" ? Float32Array : ( typeof WebGLFloatArray != "undefined" ? WebGLFloatArray : Array );
function IdentityMat44() {
var m = new glArrayType(16);
m[0] = 1; m[1] = 0; m[2] = 0; m[3] = 0;
m[4] = 0; m[5] = 1; m[6] = 0; m[7] = 0;
m[8] = 0; m[9] = 0; m[10] = 1; m[11] = 0;
m[12] = 0; m[13] = 0; m[14] = 0; m[15] = 1;
return m;
};
function RotateAxis(matA, angRad, axis) {
var aMap = [ [1, 2], [2, 0], [0, 1] ];
var a0 = aMap[axis][0], a1 = aMap[axis][1];
var sinAng = Math.sin(angRad), cosAng = Math.cos(angRad);
var matB = new glArrayType(16);
for ( var i = 0; i < 16; ++ i ) matB[i] = matA[i];
for ( var i = 0; i < 3; ++ i ) {
matB[a0*4+i] = matA[a0*4+i] * cosAng + matA[a1*4+i] * sinAng;
matB[a1*4+i] = matA[a0*4+i] * -sinAng + matA[a1*4+i] * cosAng;
}
return matB;
}
function Cross( a, b ) { return [ a[1] * b[2] - a[2] * b[1], a[2] * b[0] - a[0] * b[2], a[0] * b[1] - a[1] * b[0], 0.0 ]; }
function Dot( a, b ) { return a[0]*b[0] + a[1]*b[1] + a[2]*b[2]; }
function Normalize( v ) {
var len = Math.sqrt( v[0] * v[0] + v[1] * v[1] + v[2] * v[2] );
return [ v[0] / len, v[1] / len, v[2] / len ];
}
var Camera = {};
Camera.create = function() {
this.pos = [0, 3, 0.0];
this.target = [0, 0, 0];
this.up = [0, 0, 1];
this.fov_y = 90;
this.vp = [800, 600];
this.near = 0.5;
this.far = 100.0;
}
Camera.Perspective = function() {
var fn = this.far + this.near;
var f_n = this.far - this.near;
var r = this.vp[0] / this.vp[1];
var t = 1 / Math.tan( Math.PI * this.fov_y / 360 );
var m = IdentityMat44();
m[0] = t/r; m[1] = 0; m[2] = 0; m[3] = 0;
m[4] = 0; m[5] = t; m[6] = 0; m[7] = 0;
m[8] = 0; m[9] = 0; m[10] = -fn / f_n; m[11] = -1;
m[12] = 0; m[13] = 0; m[14] = -2 * this.far * this.near / f_n; m[15] = 0;
return m;
}
Camera.LookAt = function() {
var mz = Normalize( [ this.pos[0]-this.target[0], this.pos[1]-this.target[1], this.pos[2]-this.target[2] ] );
var mx = Normalize( Cross( this.up, mz ) );
var my = Normalize( Cross( mz, mx ) );
var tx = Dot( mx, this.pos );
var ty = Dot( my, this.pos );
var tz = Dot( [-mz[0], -mz[1], -mz[2]], this.pos );
var m = IdentityMat44();
m[0] = mx[0]; m[1] = my[0]; m[2] = mz[0]; m[3] = 0;
m[4] = mx[1]; m[5] = my[1]; m[6] = mz[1]; m[7] = 0;
m[8] = mx[2]; m[9] = my[2]; m[10] = mz[2]; m[11] = 0;
m[12] = tx; m[13] = ty; m[14] = tz; m[15] = 1;
return m;
}
var ShaderProgram = {};
ShaderProgram.Create = function( shaderList ) {
var shaderObjs = [];
for ( var i_sh = 0; i_sh < shaderList.length; ++ i_sh ) {
var shderObj = this.CompileShader( shaderList[i_sh].source, shaderList[i_sh].stage );
if ( shderObj == 0 )
return 0;
shaderObjs.push( shderObj );
}
var progObj = this.LinkProgram( shaderObjs )
if ( progObj != 0 ) {
progObj.attribIndex = {};
var noOfAttributes = gl.getProgramParameter( progObj, gl.ACTIVE_ATTRIBUTES );
for ( var i_n = 0; i_n < noOfAttributes; ++ i_n ) {
var name = gl.getActiveAttrib( progObj, i_n ).name;
progObj.attribIndex[name] = gl.getAttribLocation( progObj, name );
}
progObj.unifomLocation = {};
var noOfUniforms = gl.getProgramParameter( progObj, gl.ACTIVE_UNIFORMS );
for ( var i_n = 0; i_n < noOfUniforms; ++ i_n ) {
var name = gl.getActiveUniform( progObj, i_n ).name;
progObj.unifomLocation[name] = gl.getUniformLocation( progObj, name );
}
}
return progObj;
}
ShaderProgram.AttributeIndex = function( progObj, name ) { return progObj.attribIndex[name]; }
ShaderProgram.UniformLocation = function( progObj, name ) { return progObj.unifomLocation[name]; }
ShaderProgram.Use = function( progObj ) { gl.useProgram( progObj ); }
ShaderProgram.SetUniformI1 = function( progObj, name, val ) { if(progObj.unifomLocation[name]) gl.uniform1i( progObj.unifomLocation[name], val ); }
ShaderProgram.SetUniformF1 = function( progObj, name, val ) { if(progObj.unifomLocation[name]) gl.uniform1f( progObj.unifomLocation[name], val ); }
ShaderProgram.SetUniformF2 = function( progObj, name, arr ) { if(progObj.unifomLocation[name]) gl.uniform2fv( progObj.unifomLocation[name], arr ); }
ShaderProgram.SetUniformF3 = function( progObj, name, arr ) { if(progObj.unifomLocation[name]) gl.uniform3fv( progObj.unifomLocation[name], arr ); }
ShaderProgram.SetUniformF4 = function( progObj, name, arr ) { if(progObj.unifomLocation[name]) gl.uniform4fv( progObj.unifomLocation[name], arr ); }
ShaderProgram.SetUniformM33 = function( progObj, name, mat ) { if(progObj.unifomLocation[name]) gl.uniformMatrix3fv( progObj.unifomLocation[name], false, mat ); }
ShaderProgram.SetUniformM44 = function( progObj, name, mat ) { if(progObj.unifomLocation[name]) gl.uniformMatrix4fv( progObj.unifomLocation[name], false, mat ); }
ShaderProgram.CompileShader = function( source, shaderStage ) {
var shaderScript = document.getElementById(source);
if (shaderScript)
source = shaderScript.text;
var shaderObj = gl.createShader( shaderStage );
gl.shaderSource( shaderObj, source );
gl.compileShader( shaderObj );
var status = gl.getShaderParameter( shaderObj, gl.COMPILE_STATUS );
if ( !status ) alert(gl.getShaderInfoLog(shaderObj));
return status ? shaderObj : null;
}
ShaderProgram.LinkProgram = function( shaderObjs ) {
var prog = gl.createProgram();
for ( var i_sh = 0; i_sh < shaderObjs.length; ++ i_sh )
gl.attachShader( prog, shaderObjs[i_sh] );
gl.linkProgram( prog );
status = gl.getProgramParameter( prog, gl.LINK_STATUS );
if ( !status ) alert("Could not initialise shaders");
gl.useProgram( null );
return status ? prog : null;
}
var VertexBuffer = {};
VertexBuffer.Create = function( attributes, indices ) {
var buffer = {};
buffer.buf = [];
buffer.attr = []
for ( var i = 0; i < attributes.length; ++ i ) {
buffer.buf.push( gl.createBuffer() );
buffer.attr.push( { size : attributes[i].attrSize, loc : attributes[i].attrLoc } );
gl.bindBuffer( gl.ARRAY_BUFFER, buffer.buf[i] );
gl.bufferData( gl.ARRAY_BUFFER, new Float32Array( attributes[i].data ), gl.STATIC_DRAW );
}
buffer.inx = gl.createBuffer();
gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, buffer.inx );
gl.bufferData( gl.ELEMENT_ARRAY_BUFFER, new Uint16Array( indices ), gl.STATIC_DRAW );
buffer.inxLen = indices.length;
gl.bindBuffer( gl.ARRAY_BUFFER, null );
gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, null );
return buffer;
}
VertexBuffer.Draw = function( bufObj ) {
for ( var i = 0; i < bufObj.buf.length; ++ i ) {
gl.bindBuffer( gl.ARRAY_BUFFER, bufObj.buf[i] );
gl.vertexAttribPointer( bufObj.attr[i].loc, bufObj.attr[i].size, gl.FLOAT, false, 0, 0 );
gl.enableVertexAttribArray( bufObj.attr[i].loc );
}
gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufObj.inx );
gl.drawElements( gl.TRIANGLES, bufObj.inxLen, gl.UNSIGNED_SHORT, 0 );
for ( var i = 0; i < bufObj.buf.length; ++ i )
gl.disableVertexAttribArray( bufObj.attr[i].loc );
gl.bindBuffer( gl.ARRAY_BUFFER, null );
gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, null );
}
initScene();
})();html,body {
height: 100%;
width: 100%;
margin: 0;
overflow: hidden;
}
#gui {
position : absolute;
top : 0;
left : 0;
}<script id="draw-shader-vs" type="x-shader/x-vertex">
precision highp float;
attribute vec3 inPos;
attribute vec3 inNV;
attribute vec3 inCol;
varying vec3 vertPos;
varying vec3 vertNV;
varying vec3 vertCol;
uniform mat4 u_projectionMat44;
uniform mat4 u_viewMat44;
uniform mat4 u_modelMat44;
void main()
{
mat4 mv = u_viewMat44 * u_modelMat44;
vertCol = inCol;
vertNV = normalize(mat3(mv) * inNV);
vec4 viewPos = mv * vec4( inPos, 1.0 );
vertPos = viewPos.xyz;
gl_Position = u_projectionMat44 * viewPos;
}
</script>
<script id="draw-shader-fs" type="x-shader/x-fragment">
precision mediump float;
varying vec3 vertPos;
varying vec3 vertNV;
varying vec3 vertCol;
uniform float u_shininess;
uniform float u_glow;
void main()
{
vec3 color = vertCol;
vec3 normalV = normalize( vertNV );
vec3 eyeV = normalize( -vertPos );
vec3 halfV = normalize( eyeV + normalV );
float NdotH = max( 0.0, dot( normalV, halfV ) );
float shineFac = ( u_shininess + 2.0 ) * pow( NdotH, u_shininess ) / ( 2.0 * 3.14159265 );
gl_FragColor = vec4( u_glow*0.1 + color.rgb * u_glow * shineFac * 0.5, 1.0 );
}
</script>
<script id="post-shader-vs" type="x-shader/x-vertex">
precision mediump float;
attribute vec2 inPos;
varying vec2 pos;
void main()
{
pos = inPos;
gl_Position = vec4( inPos, 0.0, 1.0 );
}
</script>
<script id="blurX-shader-fs" type="x-shader/x-fragment">
precision mediump float;
varying vec2 pos;
uniform sampler2D u_texture;
uniform vec2 u_textureSize;
uniform float u_sigma;
float CalcGauss( float x, float sigma )
{
float coeff = 1.0 / (2.0 * 3.14157 * sigma);
float expon = -(x*x) / (2.0 * sigma);
return (coeff*exp(expon));
}
void main()
{
vec2 texC = pos.st * 0.5 + 0.5;
vec4 texCol = texture2D( u_texture, texC );
vec4 gaussCol = vec4( texCol.rgb, 1.0 );
float stepX = 1.0 / u_textureSize.x;
for ( int i = 1; i <= 20; ++ i )
{
float weight = CalcGauss( float(i) / 32.0, u_sigma * 0.5 );
texCol = texture2D( u_texture, texC + vec2( float(i) * stepX, 0.0 ) );
gaussCol += vec4( texCol.rgb * weight, weight );
texCol = texture2D( u_texture, texC - vec2( float(i) * stepX, 0.0 ) );
gaussCol += vec4( texCol.rgb * weight, weight );
}
gaussCol.rgb /= gaussCol.w;
gl_FragColor = vec4( gaussCol.rgb, 1.0 );
}
</script>
<script id="blurY-shader-fs" type="x-shader/x-fragment">
precision mediump float;
varying vec2 pos;
uniform sampler2D u_texture;
uniform vec2 u_textureSize;
uniform float u_sigma;
float CalcGauss( float x, float sigma )
{
float coeff = 1.0 / (2.0 * 3.14157 * sigma);
float expon = -(x*x) / (2.0 * sigma);
return (coeff*exp(expon));
}
void main()
{
vec2 texC = pos.st * 0.5 + 0.5;
vec4 texCol = texture2D( u_texture, texC );
vec4 gaussCol = vec4( texCol.rgb, 1.0 );
float stepY = 1.0 / u_textureSize.y;
for ( int i = 1; i <= 20; ++ i )
{
float weight = CalcGauss( float(i) / 32.0, u_sigma * 0.5 );
texCol = texture2D( u_texture, texC + vec2( 0.0, float(i) * stepY ) );
gaussCol += vec4( texCol.rgb * weight, weight );
texCol = texture2D( u_texture, texC - vec2( 0.0, float(i) * stepY ) );
gaussCol += vec4( texCol.rgb * weight, weight );
}
vec3 hdrCol = 2.0 * gaussCol.xyz / gaussCol.w;
vec3 mappedCol = vec3( 1.0 ) - exp( -hdrCol.rgb * 3.0 );
gl_FragColor = vec4( clamp( mappedCol.rgb, 0.0, 1.0 ), 1.0 );
}
</script>
<div>
<form id="gui" name="inputs">
<table>
<tr> <td> <font color= #CCF>shininess</font> </td>
<td> <input type="range" id="shine" min="0" max="50" value="10" onchange="changeEventHandler(event);"/></td> </tr>
<tr> <td> <font color= #CCF>glow</font> </td>
<td> <input type="range" id="glow" min="100" max="400" value="250" onchange="changeEventHandler(event);"/></td> </tr>
<tr> <td> <font color= #CCF>blur</font> </td>
<td> <input type="range" id="sigma" min="1" max="100" value="60" onchange="changeEventHandler(event);"/></td> </tr>
</table>
</form>
</div>
<canvas id="canvas" style="border: none;" width="100%" height="100%"></canvas>Solution 2
The website GLSL Sandbox has a collection of shader examples. This one has the glow and appears to be able to compile for ES.
You should be able to modify these to pull uv's from your texture.
Here is some code directly from this site:
#ifdef GL_ES
precision mediump float;
#endif
#extension GL_OES_standard_derivatives : enable
uniform float time;
uniform vec2 mouse;
uniform vec2 resolution;
void main(void){
vec2 p = (gl_FragCoord.xy * 2.0 - resolution) / min(resolution.x, resolution.y);
vec3 color1 = vec3(0.0, 0.3, 0.5);
vec3 color2 = vec3(0.5, 0.0, 0.3);
float f = 0.0;
float g = 0.0;
float h = 0.0;
float PI = 3.14159265;
for(float i = 0.0; i < 40.0; i++){
if (floor(mouse.x * 41.0) < i)
break;
float s = sin(time + i * PI / 20.0) * 0.8;
float c = cos(time + i * PI / 20.0) * 0.8;
float d = abs(p.x + c);
float e = abs(p.y + s);
f += 0.001 / d;
g += 0.001 / e;
h += 0.00003 / (d * e);
}
gl_FragColor = vec4(f * color1 + g * color2 + vec3(h), 1.0);
}
Author by
st4wik
Updated on July 09, 2022Comments
-
st4wik almost 2 years
I'm writing a 3D app for iOS. I'm new to OpenGL ES 2.0, so I'm still getting myself around writing basic shaders. I really need to implement a "Glow" effect on some of my models, based on the texturing.
Here's a sample:
. I'm looking for code examples for OpenGL ES 2.0. Most code I find on the internet is either for desktop OpenGL or D3D.
Any ideas?
-
wdanxna over 6 yearsthanks for the great answer, but why this line 'vertPos = pos.xyz / pos.w;' in the vertex shader?. is it necessary to divide by w here. I thought the w is always 1 at this stage. -
Rabbid76 over 6 years@wdanxna No in this case it is not necessary. -
Summit over 3 years@Rabbid76 the first shader in your code , is it code for fragment shader.
-
Rabbid76 over 3 years@Summit There was a typo
fragColorhas to begl_FragColor. The code in the example at the bottom of the answer is correct.
