Matrix4.getRotation returns rotation with scale

[Vineg]

It seems to be misleading, since there is at least one place in codebase where Matrix4.getRotation is used as rotation-only. For example it leads to dim lighting of scaled point clouds, since normals are scaled as well. I think this place requires carefull review of existing usages and maybe change the name or normalize result by scale.

var viewer = new Cesium.Viewer('cesiumContainer');
viewer.clock.currentTime = new Cesium.JulianDate(2457522.154792);

var tileset = new Cesium.Cesium3DTileset({
    url: '../../SampleData/Cesium3DTiles/PointCloud/PointCloudNormals/tileset.json'
});
viewer.scene.primitives.add(tileset);
viewer.zoomTo(tileset, new Cesium.HeadingPitchRange(0.0, -1.0, 50.0));
var style = {};
style.pointSize = Cesium.defaultValue(style.pointSize, 5.0);
tileset.style = new Cesium.Cesium3DTileStyle(style);
Cesium.Matrix4.setScale(tileset.modelMatrix, new Cesium.Cartesian3(3,3,3), tileset.modelMatrix);

[Vineg]

this is what expected

[hpinkos]

Thanks for opening up the issue @Vineg! This seems like a clear cut bug.

@lilleyse can you look into this?

[lilleyse]

I've been confused by this in the past too. It seems like Matrix4.getRotation has always just returned the upper left 3x3 matrix, which may include scale.

Should Matrix4.getRotation be deprecated in favor of Matrix4.getMatrix3 or Matrix3.fromMatrix4?

[Vineg]

Matrix4.getMatrix3 seems nice