197592 2019-05-04 02:18:51 -0700 [WebGL] Safari doesn't handle common no attribute use case 2020-02-23 21:12:45 -0800 1 1 1 Unclassified WebKit WebGL WebKit Nightly Build All All NEW InRadar P2 Normal --- 1 gman webkit-unassigned dino justin_fan nchase webkit-bug-importer oldest_to_newest 1533198 0 gman 2019-05-04 02:18:51 -0700 When debugging WebGL or when explaining to discussing a feature it's best to make a "MINIMAL, Complete, Verifiable, Example" For WebGL this often means using no attributes and just drawing a single POINT Example: ------- const gl = document.querySelector('canvas').getContext('webgl'); const vsrc = ` void main() { gl_PointSize = 128.0; gl_Position = vec4(0, 0, 0, 1); } `; const fsrc = ` precision highp float; void main() { gl_FragColor = vec4(1, 0, 0, 1); } `; function createShader(gl, type, src) { const s = gl.createShader(type); gl.shaderSource(s, src); gl.compileShader(s); return s; } const prg = gl.createProgram(); gl.attachShader(prg, createShader(gl, gl.VERTEX_SHADER, vsrc)); gl.attachShader(prg, createShader(gl, gl.FRAGMENT_SHADER, fsrc)); gl.linkProgram(prg); gl.useProgram(prg); gl.clearColor(0, 0, 1, 1); gl.clear(gl.COLOR_BUFFER_BIT); gl.drawArrays(gl.POINTS, 0, 1); ----- No attributes needed. This is great as it keeps the sample minimal so is perfect as a starting point for fragment shader based examples. I've used it 100s of times on Stack Overflow and other places to demonstrate WebGL solutions. It incorrectly fails on Safari only Here's the relevant conformance test https://www.khronos.org/registry/webgl/sdk/tests/conformance/rendering/point-no-attributes.html?webglVersion=1&quiet=0 1533199 1 gman 2019-05-04 02:23:16 -0700 Note that changing the vertex shader to this attribute vec4 position void main() { gl_PointSize = 128.0; gl_Position = position; } also fails but is perfectly valid WebGL with no attributes. Attributes have a default value of 0,0,0,1 so this will produce the same result as the previous example. Similarly you can set the attribute's constant value with `gl.vertexAttrib4f(...)` and draw points around the canvas. 1533270 2 webkit-bug-importer 2019-05-04 23:59:15 -0700 <rdar://problem/50477704> 1622050 3 nchase 2020-02-23 21:12:45 -0800 I’d love to see this fixed. I wish I knew where to start with a patch, but WebGL implementation is an intimidating black box to me.