3D scatter plot with GLMeshItem-s

[Matjaz]

Hello!

I just stumbled upon pyqtgraph couple days ago and i must say it looks really great! However, I am having performance issues with 3D rendering.

I want to make a 3D scatter plot, but it is really important that each point is represented by a 3D body. What I did so far was built lots of cubes with GLMeshItem and moved them to appropriate locations (rotation comes in later). This works OK only for a small set of points. Am I doing something wrong? Code below ...

glview = gl.GLViewWidget()

md = gl.MeshData(vertexes=cube)

for line in xyz:

   m1 = gl.GLMeshItem(meshdata=md, smooth=False, shader='shaded', glOptions='opaque')

   m1.translate(...)

   glview.addItem(m1)..

where cube is a list of vertices 12x3x3. I figure a faster implementation could be produced using openGL or maybe tinkering with pyqtgraph libraries?

Regards!

m

[Marmaduke Woodman]

In this case, you may benefit by switching to a vertex + face representation of your cubes, and build a single larger mesh that contains all your cubes at once by concatenating the small vertex and faces arrays. This should work nicely for many cubes.

 

 

[Matjaz]

Thank you for the tip. I put it all in one mesh. It's super fast now :) The new code is below if anyone finds it useful.

glview = gl.GLViewWidget()

cube = np.tile(cube, (xyz.shape[0], 1, 1))
xyz = xyz.repeat(36, axis=0).reshape(cube.shape[0], 3, 3)

m1 = gl.GLMeshItem(vertexes=(cube+xyz))
glview.addItem(m1)