Draw an image of a triangle using WebGL in a single HTML file. Make the canvas take the full page.
Draw an image of a triangle using WebGL in a single HTML file. Make the canvas take the full page.
# WebGL Triangle - Full Page Canvas Here's a self-contained HTML file that draws a colored triangle using WebGL with a canvas that covers the entire page:
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 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 | <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>WebGL Triangle</title> <style> /* Make the canvas fill the entire window */ body, html { margin: 0; padding: 0; width: 100%; height: 100%; overflow: hidden; } canvas { display: block; width: 100%; height: 100%; } </style> </head> <body> <canvas id="glCanvas"></canvas> <script> // Initialize WebGL when the page has loaded window.onload = function() { const canvas = document.getElementById('glCanvas'); // Get WebGL context const gl = canvas.getContext('webgl'); // If we don't have a GL context, give up now if (!gl) { alert('Unable to initialize WebGL. Your browser may not support it.'); return; } // Set canvas size to the size of the viewport function resizeCanvas() { canvas.width = window.innerWidth; canvas.height = window.innerHeight; gl.viewport(0, 0, canvas.width, canvas.height); drawScene(); } window.addEventListener('resize', resizeCanvas); resizeCanvas(); // Vertex shader program const vsSource = ` attribute vec4 aVertexPosition; attribute vec4 aVertexColor; varying lowp vec4 vColor; void main() { gl_Position = aVertexPosition; vColor = aVertexColor; } `; // Fragment shader program const fsSource = ` precision mediump float; varying lowp vec4 vColor; void main() { gl_FragColor = vColor; } `; // Initialize a shader program function initShaderProgram(gl, vsSource, fsSource) { const vertexShader = loadShader(gl, gl.VERTEX_SHADER, vsSource); const fragmentShader = loadShader(gl, gl.FRAGMENT_SHADER, fsSource); // Create the shader program const shaderProgram = gl.createProgram(); gl.attachShader(shaderProgram, vertexShader); gl.attachShader(shaderProgram, fragmentShader); gl.linkProgram(shaderProgram); // If creating the shader program failed, alert if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) { console.error('Unable to initialize the shader program: ' + gl.getProgramInfoLog(shaderProgram)); return null; } return shaderProgram; } // Creates a shader of the given type, uploads the source and compiles it function loadShader(gl, type, source) { const shader = gl.createShader(type); gl.shaderSource(shader, source); gl.compileShader(shader); // See if it compiled successfully if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) { console.error('An error occurred compiling the shaders: ' + gl.getShaderInfoLog(shader)); gl.deleteShader(shader); return null; } return shader; } // Initialize a shader program const shaderProgram = initShaderProgram(gl, vsSource, fsSource); // Collect all the info needed to use the shader program const programInfo = { program: shaderProgram, attribLocations: { vertexPosition: gl.getAttribLocation(shaderProgram, 'aVertexPosition'), vertexColor: gl.getAttribLocation(shaderProgram, 'aVertexColor'), }, }; // Draw the scene function drawScene() { // Clear the canvas gl.clearColor(0.0, 0.0, 0.0, 1.0); // Clear to black gl.clear(gl.COLOR_BUFFER_BIT); // Create a buffer for the triangle's positions const positionBuffer = gl.createBuffer(); gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer); // Create an array of positions for the triangle const positions = [ 0.0, 0.5, 0.0, // Top vertex -0.5, -0.5, 0.0, // Bottom left vertex 0.5, -0.5, 0.0, // Bottom right vertex ]; gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STATIC_DRAW); gl.vertexAttribPointer(programInfo.attribLocations.vertexPosition, 3, gl.FLOAT, false, 0, 0); gl.enableVertexAttribArray(programInfo.attribLocations.vertexPosition); // Create a buffer for the colors const colorBuffer = gl.createBuffer(); gl.bindBuffer(gl.ARRAY_BUFFER, colorBuffer); // Define colors for each vertex const colors = [ 1.0, 0.0, 0.0, 1.0, // Red (top vertex) 0.0, 1.0, 0.0, 1.0, // Green (bottom left vertex) 0.0, 0.0, 1.0, 1.0, // Blue (bottom right vertex) ]; gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW); gl.vertexAttribPointer(programInfo.attribLocations.vertexColor, 4, gl.FLOAT, false, 0, 0); gl.enableVertexAttribArray(programInfo.attribLocations.vertexColor); // Tell WebGL to use our program gl.useProgram(programInfo.program); // Draw the triangle gl.drawArrays(gl.TRIANGLES, 0, 3); } // Draw the initial scene drawScene(); }; </script> </body> </html> |
I extracted the following code from that output:
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 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 | <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>WebGL Triangle</title> <style> /* Make the canvas fill the entire window */ body, html { margin: 0; padding: 0; width: 100%; height: 100%; overflow: hidden; } canvas { display: block; width: 100%; height: 100%; } </style> </head> <body> <canvas id="glCanvas"></canvas> <script> // Initialize WebGL when the page has loaded window.onload = function() { const canvas = document.getElementById('glCanvas'); // Get WebGL context const gl = canvas.getContext('webgl'); // If we don't have a GL context, give up now if (!gl) { alert('Unable to initialize WebGL. Your browser may not support it.'); return; } // Set canvas size to the size of the viewport function resizeCanvas() { canvas.width = window.innerWidth; canvas.height = window.innerHeight; gl.viewport(0, 0, canvas.width, canvas.height); drawScene(); } window.addEventListener('resize', resizeCanvas); resizeCanvas(); // Vertex shader program const vsSource = ` attribute vec4 aVertexPosition; attribute vec4 aVertexColor; varying lowp vec4 vColor; void main() { gl_Position = aVertexPosition; vColor = aVertexColor; } `; // Fragment shader program const fsSource = ` precision mediump float; varying lowp vec4 vColor; void main() { gl_FragColor = vColor; } `; // Initialize a shader program function initShaderProgram(gl, vsSource, fsSource) { const vertexShader = loadShader(gl, gl.VERTEX_SHADER, vsSource); const fragmentShader = loadShader(gl, gl.FRAGMENT_SHADER, fsSource); // Create the shader program const shaderProgram = gl.createProgram(); gl.attachShader(shaderProgram, vertexShader); gl.attachShader(shaderProgram, fragmentShader); gl.linkProgram(shaderProgram); // If creating the shader program failed, alert if (!gl.getProgramParameter(shaderProgram, gl.LINK_STATUS)) { console.error('Unable to initialize the shader program: ' + gl.getProgramInfoLog(shaderProgram)); return null; } return shaderProgram; } // Creates a shader of the given type, uploads the source and compiles it function loadShader(gl, type, source) { const shader = gl.createShader(type); gl.shaderSource(shader, source); gl.compileShader(shader); // See if it compiled successfully if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) { console.error('An error occurred compiling the shaders: ' + gl.getShaderInfoLog(shader)); gl.deleteShader(shader); return null; } return shader; } // Initialize a shader program const shaderProgram = initShaderProgram(gl, vsSource, fsSource); // Collect all the info needed to use the shader program const programInfo = { program: shaderProgram, attribLocations: { vertexPosition: gl.getAttribLocation(shaderProgram, 'aVertexPosition'), vertexColor: gl.getAttribLocation(shaderProgram, 'aVertexColor'), }, }; // Draw the scene function drawScene() { // Clear the canvas gl.clearColor(0.0, 0.0, 0.0, 1.0); // Clear to black gl.clear(gl.COLOR_BUFFER_BIT); // Create a buffer for the triangle's positions const positionBuffer = gl.createBuffer(); gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer); // Create an array of positions for the triangle const positions = [ 0.0, 0.5, 0.0, // Top vertex -0.5, -0.5, 0.0, // Bottom left vertex 0.5, -0.5, 0.0, // Bottom right vertex ]; gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STATIC_DRAW); gl.vertexAttribPointer(programInfo.attribLocations.vertexPosition, 3, gl.FLOAT, false, 0, 0); gl.enableVertexAttribArray(programInfo.attribLocations.vertexPosition); // Create a buffer for the colors const colorBuffer = gl.createBuffer(); gl.bindBuffer(gl.ARRAY_BUFFER, colorBuffer); // Define colors for each vertex const colors = [ 1.0, 0.0, 0.0, 1.0, // Red (top vertex) 0.0, 1.0, 0.0, 1.0, // Green (bottom left vertex) 0.0, 0.0, 1.0, 1.0, // Blue (bottom right vertex) ]; gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(colors), gl.STATIC_DRAW); gl.vertexAttribPointer(programInfo.attribLocations.vertexColor, 4, gl.FLOAT, false, 0, 0); gl.enableVertexAttribArray(programInfo.attribLocations.vertexColor); // Tell WebGL to use our program gl.useProgram(programInfo.program); // Draw the triangle gl.drawArrays(gl.TRIANGLES, 0, 3); } // Draw the initial scene drawScene(); }; </script> </body> </html> |
Rendering the webpage gives the following image:
This is a screenshot of a webpage that draws something with webgl. I'm trying to see if it drew what I wanted. Describe what is drawn in this image?
The image is completely black, so it seems that nothing is visibly drawn. If you expected something specific to appear, you might want to check the WebGL code or ensure that the rendering context is set up correctly.
Does this answer say that there is a picture of a triangle "The image is completely black, so it seems that nothing is visibly drawn. If you expected something specific to appear, you might want to check the WebGL code or ensure that the rendering context is set up correctly."? Answer "Yes it does" or "No it does not".
No it does not.
Testing if the previous output contains the string es it does
: False
Testing if the previous output contains the string THREE.
: False
Draw an image of a triangle using WebGL in a single HTML file. Make the canvas take the full page.
Draw an image of a triangle using WebGL in a single HTML file. Make the canvas take the full page.
# WebGL Triangle Full-page Canvas Here's a complete HTML file that uses WebGL to draw a triangle. The canvas will take up the full page:
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 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 | <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>WebGL Triangle</title> <style> body, html { margin: 0; padding: 0; width: 100%; height: 100%; overflow: hidden; } canvas { display: block; width: 100%; height: 100%; } </style> </head> <body> <canvas id="glCanvas"></canvas> <script> // Initialize WebGL when the page loads window.onload = function() { const canvas = document.getElementById('glCanvas'); // Set canvas dimensions to match window canvas.width = window.innerWidth; canvas.height = window.innerHeight; // Get WebGL context const gl = canvas.getContext('webgl'); if (!gl) { alert('WebGL not supported by your browser!'); return; } // Vertex shader source const vertexShaderSource = ` attribute vec2 a_position; void main() { gl_Position = vec4(a_position, 0.0, 1.0); } `; // Fragment shader source const fragmentShaderSource = ` precision mediump float; void main() { gl_FragColor = vec4(0.0, 0.7, 1.0, 1.0); // Blue color } `; // Create shaders const vertexShader = createShader(gl, gl.VERTEX_SHADER, vertexShaderSource); const fragmentShader = createShader(gl, gl.FRAGMENT_SHADER, fragmentShaderSource); // Create program const program = createProgram(gl, vertexShader, fragmentShader); gl.useProgram(program); // Create buffer const positionBuffer = gl.createBuffer(); gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer); // Triangle vertices const positions = [ 0.0, 0.5, // Top vertex -0.5, -0.5, // Bottom left vertex 0.5, -0.5 // Bottom right vertex ]; gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STATIC_DRAW); // Connect buffer to attribute const positionAttributeLocation = gl.getAttribLocation(program, 'a_position'); gl.enableVertexAttribArray(positionAttributeLocation); gl.vertexAttribPointer( positionAttributeLocation, 2, // 2 components per vertex gl.FLOAT, // data type false, // no normalization 0, // stride (0 = auto) 0 // offset ); // Set viewport gl.viewport(0, 0, canvas.width, canvas.height); // Clear canvas gl.clearColor(0.1, 0.1, 0.1, 1.0); gl.clear(gl.COLOR_BUFFER_BIT); // Draw triangle gl.drawArrays(gl.TRIANGLES, 0, 3); // Handle window resize window.addEventListener('resize', function() { canvas.width = window.innerWidth; canvas.height = window.innerHeight; gl.viewport(0, 0, canvas.width, canvas.height); gl.clear(gl.COLOR_BUFFER_BIT); gl.drawArrays(gl.TRIANGLES, 0, 3); }); }; // Helper function to create a shader function createShader(gl, type, source) { const shader = gl.createShader(type); gl.shaderSource(shader, source); gl.compileShader(shader); if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) { console.error('Shader compilation error:', gl.getShaderInfoLog(shader)); gl.deleteShader(shader); return null; } return shader; } // Helper function to create a program function createProgram(gl, vertexShader, fragmentShader) { const program = gl.createProgram(); gl.attachShader(program, vertexShader); gl.attachShader(program, fragmentShader); gl.linkProgram(program); if (!gl.getProgramParameter(program, gl.LINK_STATUS)) { console.error('Program linking error:', gl.getProgramInfoLog(program)); return null; } return program; } </script> </body> </html> |
I extracted the following code from that output:
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 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 | <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>WebGL Triangle</title> <style> body, html { margin: 0; padding: 0; width: 100%; height: 100%; overflow: hidden; } canvas { display: block; width: 100%; height: 100%; } </style> </head> <body> <canvas id="glCanvas"></canvas> <script> // Initialize WebGL when the page loads window.onload = function() { const canvas = document.getElementById('glCanvas'); // Set canvas dimensions to match window canvas.width = window.innerWidth; canvas.height = window.innerHeight; // Get WebGL context const gl = canvas.getContext('webgl'); if (!gl) { alert('WebGL not supported by your browser!'); return; } // Vertex shader source const vertexShaderSource = ` attribute vec2 a_position; void main() { gl_Position = vec4(a_position, 0.0, 1.0); } `; // Fragment shader source const fragmentShaderSource = ` precision mediump float; void main() { gl_FragColor = vec4(0.0, 0.7, 1.0, 1.0); // Blue color } `; // Create shaders const vertexShader = createShader(gl, gl.VERTEX_SHADER, vertexShaderSource); const fragmentShader = createShader(gl, gl.FRAGMENT_SHADER, fragmentShaderSource); // Create program const program = createProgram(gl, vertexShader, fragmentShader); gl.useProgram(program); // Create buffer const positionBuffer = gl.createBuffer(); gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer); // Triangle vertices const positions = [ 0.0, 0.5, // Top vertex -0.5, -0.5, // Bottom left vertex 0.5, -0.5 // Bottom right vertex ]; gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(positions), gl.STATIC_DRAW); // Connect buffer to attribute const positionAttributeLocation = gl.getAttribLocation(program, 'a_position'); gl.enableVertexAttribArray(positionAttributeLocation); gl.vertexAttribPointer( positionAttributeLocation, 2, // 2 components per vertex gl.FLOAT, // data type false, // no normalization 0, // stride (0 = auto) 0 // offset ); // Set viewport gl.viewport(0, 0, canvas.width, canvas.height); // Clear canvas gl.clearColor(0.1, 0.1, 0.1, 1.0); gl.clear(gl.COLOR_BUFFER_BIT); // Draw triangle gl.drawArrays(gl.TRIANGLES, 0, 3); // Handle window resize window.addEventListener('resize', function() { canvas.width = window.innerWidth; canvas.height = window.innerHeight; gl.viewport(0, 0, canvas.width, canvas.height); gl.clear(gl.COLOR_BUFFER_BIT); gl.drawArrays(gl.TRIANGLES, 0, 3); }); }; // Helper function to create a shader function createShader(gl, type, source) { const shader = gl.createShader(type); gl.shaderSource(shader, source); gl.compileShader(shader); if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) { console.error('Shader compilation error:', gl.getShaderInfoLog(shader)); gl.deleteShader(shader); return null; } return shader; } // Helper function to create a program function createProgram(gl, vertexShader, fragmentShader) { const program = gl.createProgram(); gl.attachShader(program, vertexShader); gl.attachShader(program, fragmentShader); gl.linkProgram(program); if (!gl.getProgramParameter(program, gl.LINK_STATUS)) { console.error('Program linking error:', gl.getProgramInfoLog(program)); return null; } return program; } </script> </body> </html> |
Rendering the webpage gives the following image:
This is a screenshot of a webpage that draws something with webgl. I'm trying to see if it drew what I wanted. Describe what is drawn in this image?
The image shows a blue triangle centered on a dark gray background.
Does this answer say that there is a picture of a triangle "The image shows a blue triangle centered on a dark gray background."? Answer "Yes it does" or "No it does not".
Yes it does.
Testing if the previous output contains the string es it does
: True
Testing if the previous output contains the string THREE.
: False