-
Notifications
You must be signed in to change notification settings - Fork 0
Expand file tree
/
Copy pathHelloTriangle.js
More file actions
64 lines (50 loc) · 1.53 KB
/
HelloTriangle.js
File metadata and controls
64 lines (50 loc) · 1.53 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
var VSHADER_SOURCE =
'attribute vec4 a_Position;' +
'void main(){'+
'gl_Position = a_Position;'+
'}';
var FSHADER_SOURCE =
'void main(){gl_FragColor = vec4(1.0,0.0,0.0,1.0);}';
function main(){
var canvas = document.getElementById('webgl');
var gl=getWebGLContext(canvas);
if(!gl){
console.log('Failed to get the rendering context!');
return;
}
if(!initShaders(gl,VSHADER_SOURCE,FSHADER_SOURCE)){
console.log('Failed to initialize shaders');
return;
}
var n = initVertexBuffers(gl);
if(n<0){
console.log('Failed to set the positions of the vertices');
return;
}
gl.clear(gl.COLOR_BUFFER_BIT);
//gl.drawArrays(gl.TRIANGLES,0 , n);
//gl.drawArrays(gl.LINES , 0 , n);
//gl.drawArrays(gl.LINE_STRIP , 0 , n);
gl.drawArrays(gl.LINE_LOOP , 0 , n);
}
function initVertexBuffers(gl){
var vertices = new Float32Array([
0.0,0.5,-0.5,-0.5,0.5,-0.5
]);
var n = 3;
var vertexBuffer = gl.createBuffer();
if(!vertexBuffer){
console.log('Failed to create the buffer object');
return -1;
}
gl.bindBuffer(gl.ARRAY_BUFFER , vertexBuffer);
gl.bufferData(gl.ARRAY_BUFFER , vertices , gl.STATIC_DRAW);
var a_Position = gl.getAttribLocation(gl.program , 'a_Position');
if(a_Position<0){
console.log('Failed to get the stroage location');
return -1;
}
gl.vertexAttribPointer(a_Position , 2 , gl.FLOAT , false , 0,0);
gl.enableVertexAttribArray(a_Position);
return n;
}