mirror of
https://github.com/servo/servo
synced 2026-05-13 10:27:03 +02:00
112 lines
3.6 KiB
HTML
112 lines
3.6 KiB
HTML
<!doctype html>
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<html>
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<meta charset="utf-8">
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<title>WebGL texture test</title>
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<!--
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This test should show a 256x256 red square
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with a 128x128 white square embedded in the
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middle
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-->
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<style>
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html, body { margin: 0 }
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</style>
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<canvas id="c" width="256" height="256"></canvas>
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<script id="vertex_shader" type="x-shader/x-vertex">
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precision mediump float;
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attribute vec2 a_texCoord;
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attribute vec2 a_position;
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varying vec2 v_texCoord;
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void main() {
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gl_Position = vec4(a_position, 0, 1);
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v_texCoord = a_texCoord;
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}
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</script>
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<script id="fragment_shader" type="x-shader/x-fragment">
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precision mediump float;
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uniform sampler2D u_image;
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varying vec2 v_texCoord;
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void main() {
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gl_FragColor = texture2D(u_image, v_texCoord);
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}
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</script>
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<script>
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// When passed a canvas with size but without context as a texture the
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// source should be considered a white bitmap with the given size
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var canvas_without_context = document.createElement('canvas');
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canvas_without_context.width = canvas_without_context.height = 256;
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var gl = document.getElementById('c').getContext('webgl');
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// Clear with a non-white color
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gl.clearColor(1, 0, 0, 1);
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gl.clear(gl.COLOR_BUFFER_BIT);
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// Create the program
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var vertex_shader = gl.createShader(gl.VERTEX_SHADER),
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fragment_shader = gl.createShader(gl.FRAGMENT_SHADER),
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program = gl.createProgram();
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gl.shaderSource(vertex_shader,
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document.getElementById('vertex_shader').textContent);
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gl.shaderSource(fragment_shader,
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document.getElementById('fragment_shader').textContent);
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gl.compileShader(vertex_shader);
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gl.compileShader(fragment_shader);
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gl.attachShader(program, vertex_shader);
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gl.attachShader(program, fragment_shader);
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console.log(gl.getShaderInfoLog(vertex_shader));
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console.log(gl.getShaderInfoLog(fragment_shader));
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gl.linkProgram(program);
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gl.useProgram(program);
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// Get the position from the fragment shader
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var position = gl.getAttribLocation(program, "a_position");
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var tex_position = gl.getAttribLocation(program, "a_texCoord");
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var texture_coordinates = new Float32Array([
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0.0, 0.0,
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1.0, 0.0,
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0.0, 1.0,
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0.0, 1.0,
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1.0, 0.0,
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1.0, 1.0
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]);
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var texture_buffer = gl.createBuffer();
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gl.bindBuffer(gl.ARRAY_BUFFER, texture_buffer);
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gl.bufferData(gl.ARRAY_BUFFER, texture_coordinates, gl.STATIC_DRAW);
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gl.enableVertexAttribArray(tex_position);
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gl.vertexAttribPointer(tex_position, 2, gl.FLOAT, false, 0, 0);
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var square_data = new Float32Array([
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-0.5, 0.5, // top left
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0.5, 0.5, // top right
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-0.5, -0.5, // bottom left
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-0.5, -0.5, // bottom left
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0.5, 0.5, // top right
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0.5, -0.5 // bottom right
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]);
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// Create a buffer for the square with the square
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// vertex data
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var square_buffer = gl.createBuffer();
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gl.bindBuffer(gl.ARRAY_BUFFER, square_buffer);
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gl.bufferData(gl.ARRAY_BUFFER, square_data, gl.STATIC_DRAW);
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gl.enableVertexAttribArray(position);
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gl.vertexAttribPointer(position, 2, gl.FLOAT, false, 0, 0);
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// pass the first canvas as texture
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var tex = gl.createTexture();
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gl.bindTexture(gl.TEXTURE_2D, tex);
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gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
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gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
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gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, canvas_without_context);
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gl.drawArrays(gl.TRIANGLES, 0, 6);
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console.log(gl.getError() == gl.NO_ERROR);
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</script>
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</html>
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