Hi,
I try to create a sphere based on the tutorial http://learningwebgl.com/blog/?p=1253. Since I want to use color instead of texture. I try to update a little bit (in red)and set the color to red. However, the result is not what I expected. The color is not red. It shows the multi-color in sphere. Is there any mistakes in my coding?
The following is my coding:
function initBuffers() {
var latitudeBands = 30;
var longitudeBands = 30;
var radius = 2;
var vertexPositionData = [];
var normalData = [];
[b]var vertexColorData = [];[/b]
for (var latNumber = 0; latNumber <= latitudeBands; latNumber++) {
var theta = latNumber * Math.PI / latitudeBands;
var sinTheta = Math.sin(theta);
var cosTheta = Math.cos(theta);
for (var longNumber = 0; longNumber <= longitudeBands; longNumber++) {
var phi = longNumber * 2 * Math.PI / longitudeBands;
var sinPhi = Math.sin(phi);
var cosPhi = Math.cos(phi);
var x = cosPhi * sinTheta;
var y = cosTheta;
var z = sinPhi * sinTheta;
var u = 1 - (longNumber / longitudeBands);
var v = 1 - (latNumber / latitudeBands);
normalData.push(x);
normalData.push(y);
normalData.push(z);
[b]vertexColorData = vertexColorData.concat("1.0, 0.0, 0.0, 1.0");[/b]
vertexPositionData.push(radius * x);
vertexPositionData.push(radius * y);
vertexPositionData.push(radius * z);
}
}
var indexData = [];
for (var latNumber = 0; latNumber < latitudeBands; latNumber++) {
for (var longNumber = 0; longNumber < longitudeBands; longNumber++) {
var first = (latNumber * (longitudeBands + 1)) + longNumber;
var second = first + longitudeBands + 1;
indexData.push(first);
indexData.push(second);
indexData.push(first + 1);
indexData.push(second);
indexData.push(second + 1);
indexData.push(first + 1);
}
}
vertexNormalBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, vertexNormalBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(normalData), gl.STATIC_DRAW);
vertexNormalBuffer.itemSize = 3;
vertexNormalBuffer.numItems = normalData.length / 3;
vertexColorBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, vertexColorBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertexColorData), gl.STATIC_DRAW);
vertexColorBuffer.itemSize = 4;
vertexColorBuffer.numItems = vertexColorData.length / 3;
vertexPositionBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, vertexPositionBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertexPositionData), gl.STATIC_DRAW);
vertexPositionBuffer.itemSize = 3;
vertexPositionBuffer.numItems = vertexPositionData.length / 3;
vertexIndexBuffer = gl.createBuffer();
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, vertexIndexBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(indexData), gl.STREAM_DRAW);
vertexIndexBuffer.itemSize = 1;
vertexIndexBuffer.numItems = indexData.length;
}
function drawScene() {
gl.viewport(0, 0, gl.viewportWidth, gl.viewportHeight);
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
perspective(45, gl.viewportWidth / gl.viewportHeight, 0.1, 100.0);
loadIdentity();
mvTranslate([0, 0.0, z]);
mvRotate(xRot, [0, 1, 0]);
mvRotate(yRot, [1, 0, 0]);
mvPushMatrix();
mvTranslate([0, 0, 0]);
gl.bindBuffer(gl.ARRAY_BUFFER, vertexPositionBuffer);
gl.vertexAttribPointer(shaderProgram.vertexPositionAttribute, vertexPositionBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, vertexColorBuffer);
gl.vertexAttribPointer(shaderProgram.vertexColorAttribute, vertexColorBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, vertexNormalBuffer);
gl.vertexAttribPointer(shaderProgram.vertexNormalAttribute, vertexNormalBuffer.itemSize, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, vertexIndexBuffer);
setMatrixUniforms();
gl.drawElements(gl.TRIANGLES, vertexIndexBuffer.numItems, gl.UNSIGNED_SHORT, 0);
mvPopMatrix();
}