A physics simulation program made in OpenGL. This is mostly a learning project, not a finished product.
The environment I created is essentially a vacuum with only the effect of gravity impacting the objects. This was done to keep the environment as simple as possible, though there is also code to add air to the environment, where air density and shape area is taken into account to calculate the terminal velocity of objects - though the constraint code for this was left very simple. Moments of shapes are calculated on construction, then ambient forces and their impacts are calculated 60 times per second. Additionally, it may be important that the scene is quite small, and therefore the gravity is set to a tenth of Earth so that objects don't gain velocity too quickly.
Colliders are created separately to the shape itself, as the code is set up so that they can be custom to each object. For example, when creating a new object, a box object may be made, but this box can then be given a circle collider, and the idea would be that a collider would be estimated based on it's size. Currently, the code is only capable of creating box colliders, as well as box objects, but the concept works through the use of a factory and an enum. The user declares what collider type they want a shape to have, this is then passed to the factory which will then attach the requested collider to a pointer.
The broad phase of the collision detection uses a Sort and Sweep algorithm, so that all of the objects are ordered relevantly. I went for the commonly-used x-axis ordering, where my objects are ordered from left to right. The program then sweeps across this x-axis, checking if the rightmost point of the object is further than the leftmost point of the next object, and if so, adding the current and next object to a list of 'active' objects. The program then checks for any shapes that were duplicated and removes the duplicate from the list.
The narrow phase consists of comparing, from left to right, each active shape to the adjacent active shape. First, a flag is added to tell the collider that the shape is in a narrow phase check. This converts the collider in most cases to a more accurate version of itself, for example AABBs become OBBs, and more advanced shapes would become convex. The outlier to this would be circles. Following this, a simple check is performed to determine what types of colliders are being compared, with the idea in my program that, when possible, more basic calculations will be performed. Upon determining this, a SAT algorithm is used in order to determine if there are any gaps in-between the two shapes - if not, then a collision has occurred.
The collision detection can be seen working here, where I have set it so that upon collison, both shapes should stick to the centre of the environment.
This is as far as I have gotten with this project so far, but I hope to revisit it in the future when I have more time available and continue from here.