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glTF 2.0 models dark on Android of Qualcomm platform

See original GitHub issue

Hi， Recently I used cesium to work on the mobile side. I found that my 3dtile model will become very dark on the Android platform. I found similar problems in issues. #6622 and #7403 ，But it seems that I have not found a solution. I have done a lot of testing on this problem and found that the problem comes from the value of ellipsoid.radii.x in processPbrMaterials.js, but I found this to be a fixed value of 6378137.0 in the czm_getWgs84EllipsoidEC method. But I replaced ellipsoid.radii.x with a specific value, and the program works fine on mobile devices, so I don’t think this is a problem caused by float precision. I found some relevant information here, struct will have problems when initializing on Android devices, https://github.com/KhronosGroup/WebGL/issues/1302.

I tried to make the following modifications,Can display my model correctly on my phone。 I am not sure that this modification is the best. If there is a better way, please let me know, I am willing to continue working for it and contribute my code.

1552634222682

I wrote a test code that will display a green square on the pc, but will display a red square on Android, the phone processor is Snapdragon 845, the browser is chrome, Both tests failed on Xiaomi and Samsung phones… But I tested it on Huawei phones. pc： xiaomi：

this is my test code：

<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>Struct constructor/initializers highp bug.</title> </head> <body> <canvas id="canvas" width="256" height="256"> </canvas> <script type="application/javascript"> "use strict"; var canvas = document.getElementById('canvas'); var gl = canvas.getContext('webgl'); gl.viewport(0, 0, canvas.width, canvas.height); gl.clearColor(0, 0, 1, 1); gl.clear(gl.COLOR_BUFFER_BIT);

    var vs = gl.createShader(gl.VERTEX_SHADER);
    var vs_code =`
        attribute vec4 pos;
        void main(){
            gl_Position = pos;
        }
    `;
    gl.shaderSource(vs, vs_code);
    gl.compileShader(vs);

    var fs = gl.createShader(gl.FRAGMENT_SHADER);
    var fs_code =`
        precision highp float;
        struct Test {
             vec3 color;
         };
         void main() {
             vec3 color = vec3( 6378137.0, 0.0, 0.0 );
             Test test;
             test.color = color;
             if (test.color.x == 6000000.0) {
                gl_FragColor = vec4( 1.0, 0.0, 0.0, 1.0 );
             } else {
                gl_FragColor = vec4( 0.0, 1.0, 0.0, 1.0 );
             }
         }
    `;
    gl.shaderSource(fs, fs_code);
    gl.compileShader(fs);

    var prg = gl.createProgram();
    gl.attachShader(prg, vs);
    gl.attachShader(prg, fs);
    gl.linkProgram(prg);
    gl.useProgram(prg);

    var posLocation = gl.getAttribLocation(prg, 'pos');
    gl.enableVertexAttribArray(posLocation);

    var vertex = new Float32Array([
        -0.8, -0.8, 0,
        -0.8, 0.8, 0,
        0.8, 0.8, 0,
        0.8, -0.8, 0
    ]);

    var index = new Uint8Array([0, 2, 1, 0, 3, 2]);

    var vertexBuffer = gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, vertexBuffer);
    gl.bufferData(gl.ARRAY_BUFFER, vertex, gl.STATIC_DRAW);
    gl.vertexAttribPointer(posLocation, 3, gl.FLOAT, false, 0, 0);

    var indexBuffer = gl.createBuffer();
    gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
    gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, index, gl.STATIC_DRAW);
    gl.drawElements(gl.TRIANGLES, index.length, gl.UNSIGNED_BYTE, 0);

</script> </body> </html>

Issue Analytics

State:
Created 5 years ago
Comments:20 (19 by maintainers)

Top GitHub Comments

1reaction

OmarShehatacommented, Jun 27, 2019

Yeah the PR referenced above does solve this issue, I’m just reviewing for code style and tests now, I expect it to be merged end of this week/weekend.

0reactions

cesium-conciergecommented, Jun 28, 2019

Congratulations on closing the issue! I found these Cesium forum links in the comments above:

https://groups.google.com/d/msg/cesium-dev/qYjFtc3Ktg8/cjc_JId9BwAJ

If this issue affects any of these threads, please post a comment like the following:

The issue at https://github.com/AnalyticalGraphicsInc/cesium/issues/7651 has just been closed and may resolve your issue. Look for the change in the next stable release of Cesium or get it now in the master branch on GitHub https://github.com/AnalyticalGraphicsInc/cesium.

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