MinaGabriel · November 5, 2020 19:42
diff --git a/MultiAttributeColor.html b/MultiAttributeColor.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">
    // MultiAttributeColor.js (c) 2012 matsuda
    // Vertex shader program
    var VSHADER_SOURCE =
        'attribute vec4 a_Position;\n' +
        'attribute vec4 a_Color;\n' +
        'varying vec4 v_Color;\n' + // varying variable
        'void main() {\n' +
        '  gl_Position = a_Position;\n' +
        '  gl_PointSize = 10.0;\n' +
        '  v_Color = a_Color;\n' +  // Pass the data to the fragment shader
        '}\n';

    // Fragment shader program
    var FSHADER_SOURCE =
        'precision mediump float;\n' + // Precision qualifier (See Chapter 6)
        'varying vec4 v_Color;\n' +    // Receive the data from the vertex shader
        'void main() {\n' +
        '  gl_FragColor = v_Color;\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;
        }

        //
        var n = initVertexBuffers(gl);
        if (n < 0) {
            console.log('Failed to set the vertex information');
            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 verticesColors = new Float32Array([
            // Vertex coordinates and color
            0.0,  0.5,  1.0,  0.0,  0.0,
            -0.5, -0.5,  0.0,  1.0,  0.0,
            0.5, -0.5,  0.0,  0.0,  1.0,
        ]);
        var n = 3; // The number of vertices

        // Create a buffer object
        var vertexColorBuffer = gl.createBuffer();
        if (!vertexColorBuffer) {
            console.log('Failed to create the buffer object');
            return false;
        }

        // Write the vertex coordinates and colors to the buffer object
        gl.bindBuffer(gl.ARRAY_BUFFER, vertexColorBuffer);
        gl.bufferData(gl.ARRAY_BUFFER, verticesColors, gl.STATIC_DRAW);

        var FSIZE = verticesColors.BYTES_PER_ELEMENT;
        //Get the storage location of a_Position, assign and enable buffer
        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, FSIZE * 5, 0);
        gl.enableVertexAttribArray(a_Position);  // Enable the assignment of the buffer object

        // Get the storage location of a_Position, assign buffer and enable
        var a_Color = gl.getAttribLocation(gl.program, 'a_Color');
        if(a_Color < 0) {
            console.log('Failed to get the storage location of a_Color');
            return -1;
        }
        gl.vertexAttribPointer(a_Color, 3, gl.FLOAT, false, FSIZE * 5, FSIZE * 2);
        gl.enableVertexAttribArray(a_Color);  // Enable the assignment of the buffer object

        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">
	// MultiAttributeColor.js (c) 2012 matsuda
	// Vertex shader program
	var VSHADER_SOURCE =
	'attribute vec4 a_Position;\n' +
	'attribute vec4 a_Color;\n' +
	'varying vec4 v_Color;\n' + // varying variable
	'void main() {\n' +
	' gl_Position = a_Position;\n' +
	' gl_PointSize = 10.0;\n' +
	' v_Color = a_Color;\n' + // Pass the data to the fragment shader
	'}\n';

	// Fragment shader program
	var FSHADER_SOURCE =
	'precision mediump float;\n' + // Precision qualifier (See Chapter 6)
	'varying vec4 v_Color;\n' + // Receive the data from the vertex shader
	'void main() {\n' +
	' gl_FragColor = v_Color;\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;
	}

	//
	var n = initVertexBuffers(gl);
	if (n < 0) {
	console.log('Failed to set the vertex information');
	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 verticesColors = new Float32Array([
	// Vertex coordinates and color
	0.0, 0.5, 1.0, 0.0, 0.0,
	-0.5, -0.5, 0.0, 1.0, 0.0,
	0.5, -0.5, 0.0, 0.0, 1.0,
	]);
	var n = 3; // The number of vertices

	// Create a buffer object
	var vertexColorBuffer = gl.createBuffer();
	if (!vertexColorBuffer) {
	console.log('Failed to create the buffer object');
	return false;
	}

	// Write the vertex coordinates and colors to the buffer object
	gl.bindBuffer(gl.ARRAY_BUFFER, vertexColorBuffer);
	gl.bufferData(gl.ARRAY_BUFFER, verticesColors, gl.STATIC_DRAW);

	var FSIZE = verticesColors.BYTES_PER_ELEMENT;
	//Get the storage location of a_Position, assign and enable buffer
	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, FSIZE * 5, 0);
	gl.enableVertexAttribArray(a_Position); // Enable the assignment of the buffer object

	// Get the storage location of a_Position, assign buffer and enable
	var a_Color = gl.getAttribLocation(gl.program, 'a_Color');
	if(a_Color < 0) {
	console.log('Failed to get the storage location of a_Color');
	return -1;
	}
	gl.vertexAttribPointer(a_Color, 3, gl.FLOAT, false, FSIZE * 5, FSIZE * 2);
	gl.enableVertexAttribArray(a_Color); // Enable the assignment of the buffer object

	return n;
	}


	</script>


	</body></html>