Transform Tree

A simple 2D transform tree library for Odin. Best used in games requiring parent-child relationships between entities.

package main

import "core:fmt"
import "core:math"

import tt "transform_tree"

main :: proc()
{
    // - Create a transform tree with 100 reserved slots ---
    tree: tt.Transform_Tree = tt.create_tree(100, context.allocator)
    defer tt.destroy_tree(&tree)
  
    // - Set the global tree ---
    tt.global_tree = &tree
  
    // - Create a new transform and set its local values ---
    xform_a: tt.Transform = tt.alloc_transform(&tree)
    tt.local(xform_a).position = {100, 100}
    tt.local(xform_a).scale = {1, 1}
    tt.local(xform_a).rotation = math.PI
  
    // - Alternative way to get the transform's local position ---
    _ = tt.local_position(xform_a)
  
    // - Alternative way to set the transform's local position ---
    tt.set_local_position(xform_a, [2]f32{100, 100})
  
    // - Can also use shorthands (pos, scl, rot) ---
    _ = tt.local(xform_a).pos
    tt.set_local_pos(xform_a, [2]f32{100, 100})
  
    // - Create a second transform and make it a child of xform_a ---
    xform_b: tt.Transform = tt.alloc_transform(&tree, xform_a)
    tt.local(xform_b).scl = {1, 1}
    tt.local(xform_b).pos = {10, 10}
  
    // - Set the transform's global scale ---
    tt.set_global_scale(xform_b, [2]f32{0.5, 3})
  
    // - Get the transform's global values ---
    fmt.println("B's global position:", tt.global_position(xform_b))
    fmt.println("B's global scale:", tt.global_scale(xform_b))
    fmt.println("B's global rotation:", tt.global_rotation(xform_b))
  
    // - Free the transforms ---
    tt.free_transform(&tree, xform_a)
    tt.free_transform(&tree, xform_b)
}

TODO

• Core functionality
• Use freelist instead of linear search when allocating transforms
• Support for multiple float types (currently a compile-time option)
• Cache global value fetches

Not Planned

• 3D support (If I get around to this, it'll be in its own package)