Multiple Shader Programs to give different textures - webgl

Question

little lost here. trying to set different textures on different vertices. WebGL makes this extremely unnecessarily difficult. Basically I have a text file with matrices of the vertices I want, which works. (example here: http://jdmdev.net/Foundation/index.html)
But to now set different textures I would need to do something called 'texture atlassing' which there is absolutely zero documentation on how to implement that online... anywhere.
I am very new to WebGL but have an extensive programming background so I am able to understand any concepts given to me.. if I can just see something working or at the very least some documentation on it.
So I think texture atlassing is out of the picture. However, if I am understadning the WebGL pipeline as well as I think I am. Can't I just create multiple shader/vertex programs? If so, how can I go about that? I don't need a direct example, but just some code will do wonders. I just need to see this one time and I will get it, but it's impossible to find any useful stuff on the web, due to this being so new. I appreciate any help given.
Not sure how any code would help with answering this question, but here's my code that I basically used from learningwebgltutorials.com
<script id="shader-fs" type="x-shader/x-fragment">
precision mediump float;
varying vec2 vTextureCoord;
uniform sampler2D uSampler;
uniform sampler2D uSampler2;
void main(void) {
gl_FragColor = texture2D(uSampler, vec2(vTextureCoord.s, vTextureCoord.t));
}
</script>
<script id="shader-vs" type="x-shader/x-vertex">
attribute vec3 aVertexPosition;
attribute vec2 aTextureCoord;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
varying vec2 vTextureCoord;
void main(void) {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
vTextureCoord = aTextureCoord;
}
</script>
<script id="shader2-fs" type="x-shader/x-fragment">
precision mediump float;
varying vec2 vTextureCoord;
uniform sampler2D uSampler;
uniform sampler2D uSampler2;
void main(void) {
gl_FragColor = texture2D(uSampler, vec2(vTextureCoord.s, vTextureCoord.t));
}
</script>
<script id="shader2-vs" type="x-shader/x-vertex">
attribute vec3 aVertexPosition;
attribute vec2 aTextureCoord;
uniform mat4 uMVMatrix;
uniform mat4 uPMatrix;
varying vec2 vTextureCoord;
void main(void) {
gl_Position = uPMatrix * uMVMatrix * vec4(aVertexPosition, 1.0);
vTextureCoord = aTextureCoord;
}
</script>
<script type="text/javascript">
var gl;
function initGL(canvas) {
try {
gl = canvas.getContext("experimental-webgl");
gl.viewportWidth = canvas.width;
gl.viewportHeight = canvas.height;
} catch (e) {
}
if (!gl) {
alert("Could not initialise WebGL, sorry :-(");
}
}
function getShader(gl, id) {
var shaderScript = document.getElementById(id);
if (!shaderScript) {
return null;
}
var str = "";
var k = shaderScript.firstChild;
while (k) {
if (k.nodeType == 3) {
str += k.textContent;
}
k = k.nextSibling;
}
var shader;
if (shaderScript.type == "x-shader/x-fragment") {
shader = gl.createShader(gl.FRAGMENT_SHADER);
} else if (shaderScript.type == "x-shader/x-vertex") {
shader = gl.createShader(gl.VERTEX_SHADER);
} else {
return null;
}
gl.shaderSource(shader, str);
gl.compileShader(shader);
if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
alert(gl.getShaderInfoLog(shader));
return null;
}
return shader;
}
var shaderProgram;
function initShaders() {
var fragmentShader = getShader(gl, "shader-fs");
var vertexShader = getShader(gl, "shader-vs");
shaderProgram = gl.createProgram();
gl.attachShader(shaderProgram, vertexShader);
gl.attachShader(shaderProgram, fragmentShader);
gl.linkProgram(shaderProgram);
if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) {
alert("Could not initialise shaders");
}
gl.useProgram(shaderProgram);
shaderProgram.vertexPositionAttribute = gl.getAttribLocation(shaderProgram, "aVertexPosition");
gl.enableVertexAttribArray(shaderProgram.vertexPositionAttribute);
shaderProgram.textureCoordAttribute = gl.getAttribLocation(shaderProgram, "aTextureCoord");
gl.enableVertexAttribArray(shaderProgram.textureCoordAttribute);
shaderProgram.pMatrixUniform = gl.getUniformLocation(shaderProgram, "uPMatrix");
shaderProgram.mvMatrixUniform = gl.getUniformLocation(shaderProgram, "uMVMatrix");
shaderProgram.samplerUniform = gl.getUniformLocation(shaderProgram, "uSampler");
}
function handleLoadedTexture(texture) {
gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
gl.bindTexture(gl.TEXTURE_2D, texture);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, texture.image);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
gl.bindTexture(gl.TEXTURE_2D, null);
}
var mudTexture;
var rockTexture;
function initTexture() {
mudTexture = gl.createTexture();
mudTexture.image = new Image();
mudTexture.image.onload = function () {
handleLoadedTexture(mudTexture)
}
mudTexture.image.src = "mud.gif";
rockTexture = gl.createTexture();
rockTexture.image = new Image();
rockTexture.image.onload = function () {
handleLoadedTexture(rockTexture)
}
rockTexture.image.src = "rockstar.gif";
}
var mvMatrix = mat4.create();
var mvMatrixStack = [];
var pMatrix = mat4.create();
function mvPushMatrix() {
var copy = mat4.create();
mat4.set(mvMatrix, copy);
mvMatrixStack.push(copy);
}
function mvPopMatrix() {
if (mvMatrixStack.length == 0) {
throw "Invalid popMatrix!";
}
mvMatrix = mvMatrixStack.pop();
}
function setMatrixUniforms() {
gl.uniformMatrix4fv(shaderProgram.pMatrixUniform, false, pMatrix);
gl.uniformMatrix4fv(shaderProgram.mvMatrixUniform, false, mvMatrix);
}
function degToRad(degrees) {
return degrees * Math.PI / 180;
}
var currentlyPressedKeys = {};
function handleKeyDown(event) {
currentlyPressedKeys[event.keyCode] = true;
}
function handleKeyUp(event) {
currentlyPressedKeys[event.keyCode] = false;
}
var pitch = 0;
var pitchRate = 0;
var yaw = 0;
var yawRate = 0;
var xPos = 10;
var yPos = 0.4;
var zPos = 10;
var speed = 0;
function handleKeys() {
if (currentlyPressedKeys[33]) {
// Page Up
pitchRate = 0.1;
} else if (currentlyPressedKeys[34]) {
// Page Down
pitchRate = -0.1;
} else {
pitchRate = 0;
}
if (currentlyPressedKeys[37] || currentlyPressedKeys[65]) {
// Left cursor key or A
yawRate = 0.1;
} else if (currentlyPressedKeys[39] || currentlyPressedKeys[68]) {
// Right cursor key or D
yawRate = -0.1;
} else {
yawRate = 0;
}
if (currentlyPressedKeys[38] || currentlyPressedKeys[87]) {
// Up cursor key or W
speed = 0.01;
} else if (currentlyPressedKeys[40] || currentlyPressedKeys[83]) {
// Down cursor key
speed = -0.01;
} else {
speed = 0;
}
}
var worldVertexPositionBuffer = null;
var worldVertexTextureCoordBuffer = null;
function handleLoadedWorld(data) {
var lines = data.split("\n");
var vertexCount = 0;
var vertexPositions = [];
var vertexTextureCoords = [];
for (var i in lines) {
var vals = lines[i].replace(/^\s+/, "").split(/\s+/);
if (vals.length == 6 && vals[0] != "//") {
// It is a line describing a vertex; get X, Y and Z first
vertexPositions.push(parseFloat(vals[0]));
vertexPositions.push(parseFloat(vals[1]));
vertexPositions.push(parseFloat(vals[2]));
//document.write(vertexPositions[0]);
// And then the texture coords
vertexTextureCoords.push(parseFloat(vals[3]));
vertexTextureCoords.push(parseFloat(vals[4]));
//document.write(vals[4]) + "<br/>");
vertexCount += 1;
}
}
worldVertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, worldVertexPositionBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertexPositions), gl.STATIC_DRAW);
worldVertexPositionBuffer.itemSize = 3;
worldVertexPositionBuffer.numItems = vertexCount;
worldVertexTextureCoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, worldVertexTextureCoordBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertexTextureCoords), gl.STATIC_DRAW);
worldVertexTextureCoordBuffer.itemSize = 2;
worldVertexTextureCoordBuffer.numItems = vertexCount;
document.getElementById("loadingtext").textContent = "";
}
function loadWorld() {
var request = new XMLHttpRequest();
request.open("GET", "world.txt");
request.onreadystatechange = function () {
if (request.readyState == 4) {
handleLoadedWorld(request.responseText);
}
}
request.send();
}
function loadTextureValues() {
var request = new XMLHttpRequest();
request.open("GET", "world.txt");
request.onreadystatechange = function () {
if (request.readyState == 4) {
getCorrectTexture(request.responseText);
}
}
request.send();
}
var matchWithTexture = {};
function getCorrectTexture(data)
{
var lines = data.split("\n");
var vertexCount = 0;
var vertexTextureValueCoords = [];
for (var i in lines) {
var vals = lines[i].replace(/^\s+/, "").split(/\s+/);
if (vals.length == 6 && vals[0] != "//")
{
//document.write(vertexTextureValueCoords.push(parseFloat(vals[1])) + "</br>");
vertexTextureValueCoords.push(parseFloat(vals[5]));
matchWithTexture[vertexCount] = vertexTextureValueCoords[vertexCount];
vertexCount++;
}
}
}
function drawScene() {
gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
if (worldVertexTextureCoordBuffer == null || worldVertexPositionBuffer == null) {
return;
}
mat4.perspective(45, gl.viewportWidth / gl.viewportHeight, 0.1, 100.0, pMatrix);
mat4.identity(mvMatrix);
mat4.rotate(mvMatrix, degToRad(-pitch), [1, 0, 0]);
mat4.rotate(mvMatrix, degToRad(-yaw), [0, 1, 0]);
mat4.translate(mvMatrix, [-xPos, -yPos, -zPos]);
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, mudTexture);
gl.activeTexture(gl.TEXTURE1);
gl.bindTexture(gl.TEXTURE_2D, rockTexture);
loadTextureValues();
for(var key in matchWithTexture)
{
//document.write(matchWithTexture[key] + "<br/>");
if(matchWithTexture[key] == 1)
{
gl.uniform1i(shaderProgram.samplerUniform, 0);
}
else {
gl.uniform1i(shaderProgram.samplerUniform, 1);
}
}
gl.bindBuffer(gl.ARRAY_BUFFER, worldVertexTextureCoordBuffer);
gl.vertexAttribPointer(shaderProgram.textureCoordAttribute, worldVertexTextureCoordBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, worldVertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, worldVertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
setMatrixUniforms();
gl.drawArrays(gl.TRIANGLES, 0, worldVertexPositionBuffer.numItems);
}
var lastTime = 0;
// Used to make us "jog" up and down as we move forward.
var joggingAngle = 0;
function animate() {
var timeNow = new Date().getTime();
if (lastTime != 0) {
var elapsed = timeNow - lastTime;
if (speed != 0) {
xPos -= Math.sin(degToRad(yaw)) * speed * elapsed;
zPos -= Math.cos(degToRad(yaw)) * speed * elapsed;
joggingAngle += elapsed * 0.6; // 0.6 "fiddle factor" - makes it feel more realistic :-)
yPos = Math.sin(degToRad(joggingAngle)) / 20 + 0.4
}
yaw += yawRate * elapsed;
pitch += pitchRate * elapsed;
}
lastTime = timeNow;
}
function tick() {
requestAnimFrame(tick);
handleKeys();
drawScene();
animate();
}
function webGLStart() {
var canvas = document.getElementById("lesson10-canvas");
initGL(canvas);
initShaders();
initTexture();
loadWorld();
gl.clearColor(0.0, 0.0, 0.0, 1.0);
gl.enable(gl.DEPTH_TEST);
document.onkeydown = handleKeyDown;
document.onkeyup = handleKeyUp;
tick();
}
</script>
So all I did was create a 2nd shader/vertex program, and it still works. So how can I go about implementing them with different information from the first shader/vertex programs?
And a last question would be: would it just be worth it more to use a library instead of trying to do everything in webgl? I mean, with all the google searches I have done on webgl, most of all the examples/tutorials are all done using three.js, or babylon.js..etc. I'm just wondering if it's even worth it to try to do what I am doing. I guess what the question would be is, would professional settings want me to do straight up webgl, or would I (most likely) be using a library? I don't ever even plan on programming webgl, but just to know if it ever comes up in an interview.
SOLUTION VIA NO-TEXTURE ALIASING
https://github.com/jordmax12/WebGL/blob/master/Foundation%205/foundation_2.js
Since I was already parsing information from a text file for vertices and texture coordinates, there MUST be a way to do this for the texture itself (without texture aliasing).

Answer 1

You can use different textures and shaders on different vertices if you draw them one by one. The problem is that this is quite inefficient. So for good performance, I don't think there is a way around atlasing -- that's why everybody is doing this.
I am not aware of any three.js util to simplify atlasing (but I am not very familiar with three.js).
It should be straight forward to implement a utility that draws the textures to a big canvas, creating the atlas on the fly at runtime and keeping track of the coordinates. After setup, the tool would basically transform coordinates and texture names or ids to a pure coordinate array (including texture coordinates).
Whether you should use a library really depends on what you plan to do. If a retained mode API works for your use case, it's probably a good idea and more convenient to use three.js.