feat: add bullet3 collision system

[LoayAhmed304]

Most important things to notice

• Implement support for Sphere and Capsule shapes. The next commit is to have for Box shape too
• Expose raycast() function that takes target type and max distance and returns the first entity it hits of the specified type. This may be used in shooting to get the shot enemy entity (call raycast on left mouse click)

[Copilot]

Pull request overview

Integrates a Bullet3-backed collision system into the game loop, adding collider layers and exposing query helpers (raycast/overlap) for gameplay usage.

Changes:

• Add CollisionSystem (Bullet collision world integration) with per-frame collision events + basic pushback.
• Extend ColliderComponent with CollisionLayer and layer parsing from JSON.
• Wire collision system lifecycle into Playstate and add a sample collision-focused scene config.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 7 comments.

Show a summary per file

File	Description
src/states/play-state.hpp	Initializes, updates, and destroys the new collision system as part of the play loop.
src/game/systems/collision-system.hpp	Declares collision system API (update, raycast, overlapSphere) and event/result structs.
src/game/systems/collision-system.cpp	Implements Bullet world sync, contact extraction, pushback, raycast, and overlapSphere.
src/game/components/collider.hpp	Adds bitmask-based collision layers and updates ColliderComponent to use them.
src/game/components/collider.cpp	Adds JSON string → CollisionLayer parsing.
config/json-configs/collision.jsonc	Adds a sample scene demonstrating capsule/sphere colliders and layers.
CMakeLists.txt	Adds the collision system source to the build.

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[AhmedSobhy01]

With this config:

"world": [
            {
                "position": [0, 1.7, 6],
                "components": [
                    { "type": "Camera" },
                    { "type": "Free Camera Controller" }
                ]
            },
            {
                "name": "Haha",
                "scale": [2, 2, 2],
                "position": [0, 1, 0],
                "children": [
                    {
                        "components": [
                            { "type": "Mesh Renderer", "mesh": "sphere", "material": "moon" },
                            { "type": "Collider", "shape": "Sphere", "radius": 1, "layer": "enemy" }
                        ]
                    }
                ]
            },
            {
                "name": "Hehe",
                "position": [1.5, 1, 0],
                "components": [
                    { "type": "Mesh Renderer", "mesh": "sphere", "material": "metal" },
                    { "type": "Collider", "shape": "Sphere", "radius": 1, "layer": "environment" }
                ]
            }
        ]

They get separated by the wrong amount relative to the overlap, probably because the child collider only uses local scale when created, and the pushback is calculated with the wrong inverse.

[AhmedSobhy01]

Thank you sir, great addition!

Let's close this, but keep in mind we still have issues with changing scaling during runtime and also with parent scaling.

[AhmedAmrNabil]

LGTM but check comments

[AhmedAmrNabil]

LGTM

[AhmedSobhy01]

LGTM