Collision handling and first compromises -

Collision handling turned out to be harder than expected… To get it working quickly, I relied on a bounding sphere for every models. The spheres are centered on the isobarycenter of the model and have for radius the distance of this point to the farthest vertex of the model. This is far from the perfect fit possible for a given model, but was faster to code. The way it works is that game objects register themselves during their update pass to the collision handler. Afterwards, the collision handler solves collision of the registered assets.

Animated gif showing rough collision handling using spheres in full 3D - This causes a bug sliding the player vehicle slide under other assets when colliding — Game objects colliding

Collisions calculated in 3D with 2D movements, after a while models drifted on the Y axis...

Animated gif showing rough collision handling restricted in 2D - Collision handling is done in 3D but the Y component is dropped making the collision resolution 2D — Restricted collision correction to 2D

Models don't drift on Y anymore, but bounding spheres are still a poor fit for some models...

Animated gif showing collision handling of spheres - Replacing complex models with spheres, we see that collisions are better dealt with — Verifying collision handler

Using sphere models, the bounding volume fit is much improved

Time spent for this	Time spent so far
8 h	41 h

Adding collision handling was nice, but the bounding sphere fit is very poor for most models, I will need to improve that later. Also, our objects only have current data for position, nothing about current speed or acceleration. This makes the collision resolution quite janky as seen in the illustration below:

Diagram showing the problem when only position information is available to calculate collision handling. Objects will have a tendency to 'jump' when touching each others — Correcting position after collision using only position info

Not a very good way to do it... but quickest to implement!

beginning collision bounding_sphere

Suggestions de lecture :

Reworking object math for big results
Projectile and early game logic
Camera tracking and first bugfix
Adding movements, getting first bugs
First gitpush, two viewports and a spaceship!

Game objects colliding

Restricted collision correction to 2D

Verifying collision handler

Correcting position after collision using only position info

Suggestions de lecture :