MinaGabriel · November 5, 2020 18:46
diff --git a/MultiAttributeSize.html b/MultiAttributeSize.html
 <html lang="en"><head>
    <meta charset="utf-8">
    <title>Translate a Triangle</title>

 </head><body onload="main()">
 <canvas id="webgl" width="800" height="800">
    Please use a browser that supports "canvas"
 </canvas>


 <script src="https://rawgit.com/huningxin/webglbook_examples/master/lib/webgl-utils.js"></script>
 <script src="https://rawgit.com/huningxin/webglbook_examples/master/lib/webgl-debug.js"></script>
 <script src="https://rawgit.com/huningxin/webglbook_examples/master/lib/cuon-utils.js"></script>
 <script src="https://rawgit.com/huningxin/webglbook_examples/master/lib/cuon-matrix.js"></script>
 <script type="text/javascript">
    // MultiAttributeSize.js (c) 2012 matsuda
    // Vertex shader program
    var VSHADER_SOURCE =
        'attribute vec4 a_Position;\n' +
        'attribute float a_PointSize;\n' +
        'void main() {\n' +
        '  gl_Position = a_Position;\n' +
        '  gl_PointSize = a_PointSize;\n' +
        '}\n';

    // Fragment shader program
    var FSHADER_SOURCE =
        'void main() {\n' +
        '  gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);\n' +
        '}\n';

    function main() {
        // Retrieve <canvas> element
        var canvas = document.getElementById('webgl');

        // Get the rendering context for WebGL
        var gl = getWebGLContext(canvas);
        if (!gl) {
            console.log('Failed to get the rendering context for WebGL');
            return;
        }

        // Initialize shaders
        if (!initShaders(gl, VSHADER_SOURCE, FSHADER_SOURCE)) {
            console.log('Failed to intialize shaders.');
            return;
        }

        // Set the vertex information
        var n = initVertexBuffers(gl);
        if (n < 0) {
            console.log('Failed to set the positions of the vertices');
            return;
        }

        // Specify the color for clearing <canvas>
        gl.clearColor(0.0, 0.0, 0.0, 1.0);

        // Clear <canvas>
        gl.clear(gl.COLOR_BUFFER_BIT);

        // Draw three points
        gl.drawArrays(gl.POINTS, 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 sizes = new Float32Array([
            10.0, 20.0, 30.0  // Point sizes
        ]);

        // Create a buffer object
        var vertexBuffer = gl.createBuffer();
        var sizeBuffer = gl.createBuffer();
        if (!vertexBuffer || !sizeBuffer) {
            console.log('Failed to create the buffer object');
            return -1;
        }

        // Write vertex coordinates to the buffer object and enable it
        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 storage location of a_Position');
            return -1;
        }
        gl.vertexAttribPointer(a_Position, 2, gl.FLOAT, false, 0, 0);
        gl.enableVertexAttribArray(a_Position);

        // Bind the point size buffer object to target
        gl.bindBuffer(gl.ARRAY_BUFFER, sizeBuffer);
        gl.bufferData(gl.ARRAY_BUFFER, sizes, gl.STATIC_DRAW);
        var a_PointSize = gl.getAttribLocation(gl.program, 'a_PointSize');
        if(a_PointSize < 0) {
            console.log('Failed to get the storage location of a_PointSize');
            return -1;
        }
        gl.vertexAttribPointer(a_PointSize, 1, gl.FLOAT, false, 0, 0);
        gl.enableVertexAttribArray(a_PointSize);

        // Unbind the buffer object
        gl.bindBuffer(gl.ARRAY_BUFFER, null);

        return n;
    }

 </script>


 </body></html>
	<html lang="en"><head>
	<meta charset="utf-8">
	<title>Translate a Triangle</title>

	</head><body onload="main()">
	<canvas id="webgl" width="800" height="800">
	Please use a browser that supports "canvas"
	</canvas>


	<script src="https://rawgit.com/huningxin/webglbook_examples/master/lib/webgl-utils.js"></script>
	<script src="https://rawgit.com/huningxin/webglbook_examples/master/lib/webgl-debug.js"></script>
	<script src="https://rawgit.com/huningxin/webglbook_examples/master/lib/cuon-utils.js"></script>
	<script src="https://rawgit.com/huningxin/webglbook_examples/master/lib/cuon-matrix.js"></script>
	<script type="text/javascript">
	// MultiAttributeSize.js (c) 2012 matsuda
	// Vertex shader program
	var VSHADER_SOURCE =
	'attribute vec4 a_Position;\n' +
	'attribute float a_PointSize;\n' +
	'void main() {\n' +
	' gl_Position = a_Position;\n' +
	' gl_PointSize = a_PointSize;\n' +
	'}\n';

	// Fragment shader program
	var FSHADER_SOURCE =
	'void main() {\n' +
	' gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);\n' +
	'}\n';

	function main() {
	// Retrieve <canvas> element
	var canvas = document.getElementById('webgl');

	// Get the rendering context for WebGL
	var gl = getWebGLContext(canvas);
	if (!gl) {
	console.log('Failed to get the rendering context for WebGL');
	return;
	}

	// Initialize shaders
	if (!initShaders(gl, VSHADER_SOURCE, FSHADER_SOURCE)) {
	console.log('Failed to intialize shaders.');
	return;
	}

	// Set the vertex information
	var n = initVertexBuffers(gl);
	if (n < 0) {
	console.log('Failed to set the positions of the vertices');
	return;
	}

	// Specify the color for clearing <canvas>
	gl.clearColor(0.0, 0.0, 0.0, 1.0);

	// Clear <canvas>
	gl.clear(gl.COLOR_BUFFER_BIT);

	// Draw three points
	gl.drawArrays(gl.POINTS, 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 sizes = new Float32Array([
	10.0, 20.0, 30.0 // Point sizes
	]);

	// Create a buffer object
	var vertexBuffer = gl.createBuffer();
	var sizeBuffer = gl.createBuffer();
	if (!vertexBuffer \|\| !sizeBuffer) {
	console.log('Failed to create the buffer object');
	return -1;
	}

	// Write vertex coordinates to the buffer object and enable it
	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 storage location of a_Position');
	return -1;
	}
	gl.vertexAttribPointer(a_Position, 2, gl.FLOAT, false, 0, 0);
	gl.enableVertexAttribArray(a_Position);

	// Bind the point size buffer object to target
	gl.bindBuffer(gl.ARRAY_BUFFER, sizeBuffer);
	gl.bufferData(gl.ARRAY_BUFFER, sizes, gl.STATIC_DRAW);
	var a_PointSize = gl.getAttribLocation(gl.program, 'a_PointSize');
	if(a_PointSize < 0) {
	console.log('Failed to get the storage location of a_PointSize');
	return -1;
	}
	gl.vertexAttribPointer(a_PointSize, 1, gl.FLOAT, false, 0, 0);
	gl.enableVertexAttribArray(a_PointSize);

	// Unbind the buffer object
	gl.bindBuffer(gl.ARRAY_BUFFER, null);

	return n;
	}

	</script>


	</body></html>