Create a 3D model and render it in wireframe. (WebGL)

// HelloCube.js (c) 2012 matsuda // Vertex shader program var VSHADER_SOURCE = 'attribute vec4 a_Position;\n' + 'attribute vec4 a_Color;\n' + 'uniform mat4 u_MvpMatrix;\n' + 'varying vec4 v_Color;\n' + 'void main() {\n' + ' gl_Position = u_MvpMatrix * a_Position;\n' + ' v_Color = a_Color;\n' + '}\n'; // Fragment shader program var FSHADER_SOURCE = '#ifdef GL_ES\n' + 'precision mediump float;\n' + '#endif\n' + 'varying vec4 v_Color;\n' + '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; } // Set the vertex coordinates and color var n = initVertexBuffers(gl); if (n < 0) { console.log('Failed to set the vertex information'); return; } // Set clear color and enable hidden surface removal gl.clearColor(0.0, 0.0, 0.0, 1.0); gl.enable(gl.DEPTH_TEST); // Get the storage location of u_MvpMatrix var u_MvpMatrix = gl.getUniformLocation(gl.program, 'u_MvpMatrix'); if (!u_MvpMatrix) { console.log('Failed to get the storage location of u_MvpMatrix'); return; } // Set the eye point and the viewing volume var mvpMatrix = new Matrix4(); mvpMatrix.setPerspective(30, 1, 1, 100); mvpMatrix.lookAt(3, 3, 7, 0, 0, 0, 0, 1, 0); // Pass the model view projection matrix to u_MvpMatrix gl.uniformMatrix4fv(u_MvpMatrix, false, mvpMatrix.elements); // Clear color and depth buffer gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT); // Draw the cube gl.drawElements(gl.TRIANGLES, n, gl.UNSIGNED_BYTE, 0); } function initVertexBuffers(gl) { // Create a cube // v6----- v5 // /| /| // v1------v0| // | | | | // | |v7---|-|v4 // |/ |/ // v2------v3 var verticesColors = new Float32Array([ // Vertex coordinates and color 1.0, 1.0, 1.0, 1.0, 1.0, 1.0, // v0 White -1.0, 1.0, 1.0, 1.0, 0.0, 1.0, // v1 Magenta -1.0, -1.0, 1.0, 1.0, 0.0, 0.0, // v2 Red 1.0, -1.0, 1.0, 1.0, 1.0, 0.0, // v3 Yellow 1.0, -1.0, -1.0, 0.0, 1.0, 0.0, // v4 Green 1.0, 1.0, -1.0, 0.0, 1.0, 1.0, // v5 Cyan -1.0, 1.0, -1.0, 0.0, 0.0, 1.0, // v6 Blue -1.0, -1.0, -1.0, 0.0, 0.0, 0.0 // v7 Black ]); // Indices of the vertices var indices = new Uint8Array([ 0, 1, 2, 0, 2, 3, // front 0, 3, 4, 0, 4, 5, // right 0, 5, 6, 0, 6, 1, // up 1, 6, 7, 1, 7, 2, // left 7, 4, 3, 7, 3, 2, // down 4, 7, 6, 4, 6, 5 // back ]); // Create a buffer object var vertexColorBuffer = gl.createBuffer(); var indexBuffer = gl.createBuffer(); if (!vertexColorBuffer || !indexBuffer) { return -1; } // Write the vertex coordinates and color 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; // Assign the buffer object to a_Position and enable the assignment 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, 3, gl.FLOAT, false, FSIZE * 6, 0); gl.enableVertexAttribArray(a_Position); // Assign the buffer object to a_Color and enable the assignment 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 * 6, FSIZE * 3); gl.enableVertexAttribArray(a_Color); // Write the indices to the buffer object gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer); gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, indices, gl.STATIC_DRAW); return indices.length; }