Grid3D and Octree

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Brakeza3D includes Grid3D and Octree data structures integrated into Mesh3D objects.

• Grid3D: Creates a grid of X, Y, Z dimensions over the AABB of the given object.
• Octree: Creates an octree with the specified depth (maxDepth).

To create a grid in a Mesh3D object, use BuildGrid3D(sizeX, sizeY, sizeZ):

eye = ObjectFactory.Mesh3D(
    "../assets/models/Capsule.fbx",
    Vertex3D.new(x, y, z)
)
eye:BuildGrid3D(5, 5, 5)                                                    -- creates a 5x5x5 grid

To create an octree use BuildOctree(int maxDepth):

eye = ObjectFactory.Mesh3D("../assets/models/Capsule.fbx", Vertex3D.new(x, y, z))
eye:BuildOctree(1) -- creates an octree with a single depth level, only 8 children

To readjust the dimensions of both grids and octree structures, simply rerun buildGrid3D() or buildOctree().

Filling Geometry in Grid3D

Grid3D stores a boolean flag for each cell. Brakeza3D provides a method fillGrid3DFromGeometry, which sets this flag for each cell if no triangle intersects or is contained in it:

eye = ObjectFactory.Mesh3D("../assets/models/Capsule.fbx", Vertex3D.new(x, y, z))
eye:BuildGrid3D(5, 5, 5)
eye:FillGrid3DFromGeometry()                -- sets flags for empty cells

This is especially useful for pathfinding techniques.

Pathfinding in Grid3D

Grids include an A* algorithm that allows iterating over their cells. Combined with fillGrid3DFromGeometry, paths can avoid cells with geometry:

eye = ObjectFactory.Mesh3D("../assets/models/Capsule.fbx", Vertex3D.new(x, y, z))
eye:BuildGrid3D(5, 5, 5)
eye:FillGrid3DFromGeometry()                    -- fill with geometry

eye:getGrid3D():setTravel(0, 0, 0, 5, 5, 5)     -- set travel from (0,0,0) to (5,5,5)
path = eye:getGrid3D():MakeTravelCubesGrid()    -- returns an array of CubeGrid3D

Using the method setTravel(x1, y1, z1, x2, y2, z2), you can define the start and end points for the next path request made through MakeTravelCubesGrid().

The method MakeTravelCubesGrid returns the requested path as an array of CubeGrid3D structures:

struct CubeGrid3D {
    AABB3D box;             // bounding box
    int posX;               // X index in the grid
    int posY;               // Y index
    int posZ;               // Z index
    bool passed = true;     // Flag
};

You can iterate over this array to obtain the desired path:

...
path = eye:getGrid3D():MakeTravelCubesGrid()            -- we get a travel path

for i, cube in ipairs(path) do
    print("Cube " .. i .. ": X = " .. cube.posX .. ", Y = " .. cube.posY .. ", Z = " .. cube.posZ)
end
...

Click Object Detection

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Brakeza3D provides native functionality for detecting clicks on Object3D instances using raycasting.

To detect if an object was clicked, you can use the isRayCollisionWith() method from the Collisions component. This method casts a ray from one point to another and checks if it intersects with a specific object.

Basic Click Detection Example

function onUpdate()
    local input = Components:Input()

    if input:isClickLeft() then
        -- Get mouse position relative to renderer
        local mouseX = input:getRelativeRendererMouseX()
        local mouseY = input:getRelativeRendererMouseY()

        -- Get camera for ray origin
        local camera = Components:Camera():getCamera()
        local rayOrigin = camera:getPosition()

        -- Calculate ray direction from camera through mouse position
        -- (simplified - actual implementation depends on your projection)
        local rayEnd = Vertex3D.new(mouseX, mouseY, 100)

        -- Check collision with a specific object
        local targetObject = Brakeza:getSceneObjectByLabel("MyObject")
        if Components:Collisions():isRayCollisionWith(rayOrigin, rayEnd, targetObject) then
            print("Object clicked!")
        end
    end
end

Method Reference

Method	Parameters	Return	Description
isRayCollisionWith()	from: Vertex3D, to: Vertex3D, object: Object3D	bool	Returns true if the ray from from to to intersects with the specified object

note

For click detection to work properly, the target object must have collisions enabled with an appropriate collider shape configured.