Add-on: export a mesh as an OpenGL display list

Ok, I know this will only benefit very few people but that doesn't stop me from sharing :-)

A cloud of OpenGL Suzannes

What is it?

A tiny add-on that exports a small Python file containing OpenGL code to display a mesh.

What is it good for?

Blender has OpenGL bindings available for use in Python scripts. You can use these OpenGL drawing commands to display for example overlays over your 3D view with a draw handler.
If you would want to draw some sort of complex object you would have to recreate it using glVertex3f() calls which is a lot of work as soon as the model is more than a few vertices. This add-on generates the code for you in the form of a function that creates a display list.

How does it work?

When you select File -> Export -> Export mesh as OpenGL snippet it will open a file dialog and then it will write Python code to the selected file.
It will write the vertex coordinates (in object space) and the vertex normals of the active object. It will triangulate the mesh internally before writing it. There is currently no check if there is an active object or that the active object is a mesh.

What does the resulting Python code look like?

The export for a plain Suzanne mesh looks like this:

import bgl

def Suzanne():
 shapelist = bgl.glGenLists(1)
 bgl.glNewList(shapelist, bgl.GL_COMPILE)
 bgl.glBegin(bgl.GL_TRIANGLES)
 bgl.glNormal3f(0.9693,-0.245565,-0.011830)
 bgl.glVertex3f(0.4688,-0.757812,0.242188)
 bgl.glNormal3f(0.6076,-0.608505,-0.510393)
 bgl.glVertex3f(0.5000,-0.687500,0.093750)
 bgl.glNormal3f(0.8001,-0.599853,-0.002850)
        ... lots of calls omitted ...
 bgl.glVertex3f(-0.5938,0.164062,-0.125000)
 bgl.glEnd()
 bgl.glEndList()
 return shapelist

That code is so old fashioned, why?

If you ask any questions on forums like stack-overflow about older versions of OpenGL (and old in this context essentially means anything before OpenGL 3.0) you will be told over and over again that you shouldn't use it and that investing time in it is wasteful or even stupid.

You will have to live with that :-)

The fact is that even though Blender certainly runs on newer versions of OpenGL, the Python bindings it provides are based on version 2.1 and I am not sure when that will change. And yes, even 2.1 supports stuff like vertex arrays but those are quite cumbersome to use, not documented in the Blender Python API any in many situations overkill and not really a speed improvement: If all you want is some fancy overlay, using a compiled display list is pretty fast.

Where can I download it?

The add-on is available on GitHub.

Blender add-on: TextureWatch

I am happy to announce that yesterday I published my new TextureWatch add-on on Blendermarket.

As illustrated in the video, TextureWatch is a small add-on to automatically synchronize textures used in your .blend file if they change on disk. This simplifies working with external programs like Gimp or Substance Painter because TextureWatch can automatically update those textures when you save your files without the need to go through all images inside Blender one by one and selecting reload. This saves time as well as guarantees consistency.

If you find this useful you might want to take a look at my BlenderMarket store.

Graswald vs. Grass Essentials

I recently bought the Graswald add-on because the sample images looked really good and the collection of plant species, variations and leaf debris on offer was quite extensive.

A couple of years ago I also bought Grass Essentials and although that was (and is) is fine collection of grasses and weeds too, I always found it rather difficult to get naturalistic looks. Both products have options to change things like the patchiness or wetness of the plants but I feel that Graswald, being an add-on*) with all the configurable options in a toolbar panel is far easier to work with and offers some extra possibilities, like integration with weight painting for distribution and length as well as aging a percentage of the plants .

*) It is also available as an asset library without the add-on at a slightly lower price.

Example

To show you what I mean I spent some time trying to recreate a patchy grass field consisting mainly of Kentucky Rye grass sprinkled with lots of dandelions. It took me about 10 minutes to set up the Grasswald patch on the left and although the time it took to set up the Grass Essentials patch on the right was about the same, I lost some time because although Grass Essentials does have dandelion flowers and seed-heads, it does not have a particle system to represent the actual dandelion plant leaves, so I finally substituted those with plantain to get at least some leaves showing.

(click to enlarge. Image rendered in Cycles with 1000 samples, filmic color management at medium high contrast and lit by a single HDRI backplate from HDRI Haven. The ground texture barely visible below the plants was a simple dirt texture created in Substance Painter. Note that Grass Essentials bundles several good dirt textures as well.)

Conclusion

Now everybody knows I not much of an artist and probably with some extra time the Grass Essentials version could be made to look more varied and patchy but for me the ease of use and the quality of the end result speaks for itself. Given this quality and ease of use combined with the slightly lower price, Graswald easily wins out on value for money.

[These opinions are my own. I am no way affiliated with either Graswald or Grass Essentials and did pay for both products myself.]