These are examples for functionality of Panda3D. They are meant to be as minimal as possible, each showing exactly one thing, and each be executable right out of the box. The intention is rather to get you started than being complete examples of anything, though in the future further examples will delve into more advanced features.
In this course we will deal with using code to create geometric models, and animate them. We will not deal with advanced procedural generation algorithms to create complex objects, only with the underlying API that would also be used to turn such complex models into actual data that Panda3D can work on.
Special thanks go to Entikan whose trailblazing led to me developing these examples based on his code.
Here we generate a static model purely in code, so as to see what is going on under the hood. In basic_model.py we learn
- how to define a table for vertices,
- how to fill it with data,
- how to add primitives, in particular triangles.
main.py is mostly a convenience so that we can actually look at something.
Building on geometry, we discuss the properties of PBR-capable models and their textures. pbr_model.py shows
- what vertex columns a PBR model typically uses,
- what materials are and do,
- what information is encoded in textures, and how,
- how to procedurally generate images to load into textures.
There are three executable progrems this time, where
main_no_pbr.pyshows how the model looks in the default renderer,main_simplepbr.pyuses Moguri'spanda3d-simplepbrpackage,- and
main_complexpbr.pydoes the same for Simulan'spanda3d-complexpbrpackage.
Also building on geometry, we create the model of a tentacle, and give it a chain of bones to animate it around. As you will doubtlessly expect by now, bones_model.py does the same old "Create a table, fill it with vertices, add triangles" song and dance, while adding information to the vertices about which bones they should consider for changing their apparent data while the model is being animated.
There are four paradigms of animation that I am aware of, with advanced procedural animation techniques building on those. There are
- Forward Kinematics, basically just setting bones to translations generated ad hoc in code, shown in
main_control_joints.py, - Skeletal animation, which is basically the same, using pre-recorded and usually artist-generated animations; Here we use
main_mocap.pyto record an animation using rdb'smocap.py, and play it back withmain_animation.py, - Inverse Kinematics, which is the reverse of Forward Kinematics, in that the code provides a target that a chain of bones should reach for, and leaves it to mathematical tools to move the bones within provided constraints so as to reach the target, demonstrated in
main_inverse_kinematics.pyusing CCD-IK-Panda3D by germanunkol, - and Physical Simulation, where we add information about a physical approximation of our model to simulate how it moves under the influence of gravity and collisions by using Panda3D's Bullet integration as in
main_physics.py.
Let the camera rotate around the camera with your left and right cursor key.
Features demonstrated:
- Loading a model and attaching it to the scene graph
- Events
- Tasks
- Moving a node
Have an object in the scene emit a sound which is then rendered appropriately.
This example uses a sound file downloaded at http://www.freesound.org/people/lth_stp/sounds/120490/ created by the sound department of the states theater of Lower Austria (Landestheater Niederösterreich). I have dropped an audio channel (the original is stereo, this version is mono) and converted it to Ogg Vorbis. The file is licensed under the Creative Commons 3.0 license, Attribution-NonCommercial: http://creativecommons.org/licenses/by-nc/3.0/
Features demonstrated:
- 3D sound
Features not yet demonstrated:
- Doppler shift
Features demonstrated:
- Setting up and stepping a physics simulation
- Adding a Rigid Body
- Apply an impulse
This one sets up a scene and saves a cube map snapshot of it a six images in industry standard format. This should later come in handy to precreate skyboxes.
Features demonstrated:
- Save a cube map
This sets up a simple state machine that lets a sphere rotate clockwise, counterclockwise or not at all. Using the left and right cursor keys, you can switch between states.
Features demonstrated:
- Finite State Machine
Okay, it does get a bit ridiculous here. All I did here was plaster a button on the screen. I guess the point here is mostly that DirectGUI widgets reparent themselves to aspect2d automagically, so... Keep in mind to manage your scene graph?
Features demonstrated:
- DirectGUI elements
A minimal libRocket GUI
Features demonstrated:
- Loading a font
- Setting up the Python-side of the GUI
- RML / RCSS
Level of detail. I created a model of a tree on tree different detail levels and you're allowed to laugh, but even for programmers art I did them quarter-assed. Anyways, your up and down cursor keys will move you towards and away from the tree, showing how the mesh gets exchanged automagically.
Features demonstrated:
- Level of Detail nodes
If you want to use Panda3D to render frames to image files on the disk
instead of a window on the screen, that is remarkably easy; Just combine
window-type offscreen with a window's screenshot() method. To turn
the outputted images into a video, you can use
ffmpeg -framerate 30 -pattern_type glob -i '*.png' -c:v libx264 -pix_fmt yuv420p out.mp4.
Features demonstrated:
- Offscreen rendering
- Screenshots
You have a camera somewhere in your game world and a screen that shows what's on the camera? You want 2D displays showing something that's easier to model in 3D? Or you have any other purpose for having a Panda3D camera render into a texture? This is the example for you.
Features demonstrated:
- Set up a secondary scene graph, which will get rendered into textures.
- Create a butter, set its sort order.
- Create a camera and let it render into that buffer.
- Get a texture from the buffer and set it as a "monitors" texture.
Scene graph position to camera frustum position and back.
Features demonstrated:
Lens.projectLens.extrude_depth()
Features demonstrated:
- Set up a shadow-casting light.
- Make all objects in the scene graph receive shadows.
Features demonstrated:
- Minimal shader pipeline
- Full shader pipeline
I admit that this is a bit of a weird one. I've assembled an .egg file mostly by hand to tile a texture onto a cube, where the texture coords of each vertex is smack in the middle of the corner pixel of that sides tile, so that mipmapping should be avoided. The point is that with this, you can create high-quality skybox textures.
A bunch of spheres in the scene show that the skybox gets rendered "behind" objects in the scene, even though the box should be too small to contain the outer spheres.
Features demonstrated:
- Rendering objects as background
Features demonstrated:
- Post-processing effects with fragment shaders
This is mostly a copy-and-paste job of the Hello World application in Panda3D's manual, with a filter slapped on at the end. The FilterManager causes a scene to not be rendered directly to the scene, but instead to textures on a quad, which then does get fed back into fragment shading.
The buffer protocol is a Python feature that lets C extensions efficiently share memory. In the context on Panda3D, this is a viable way to share texture and vertex data with non-Panda3D modules.
Features demonstrated:
- (gizeh_to_panda3d.py) Creating images on a canvas backed by a numpy array (which is the standard way of storing images in Python), and copying it into a Panda3D texture. Requires Gizeh (a Python module for rendering vector graphics, akin to Cairo).
This is code I find helpful when developing experiments with.