Game Transform Systems

Game Transform Systems

Use this skill to make transform code explicit, composable, testable, and consistent across gameplay, rendering, physics, and tools.

Primary source: Geometry for Programmers by Oleksandr Kaleniuk (https://www.manning.com/books/geometry-for-programmers), transformed and paraphrased, especially chapter 4. Additional source: Khronos glTF 2.0 specification transform and coordinate-system conventions (https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html).

Core Workflow

1. List every coordinate space involved: model, local, parent, world, view, clip, screen, texture, grid, or field space.
2. Define conventions once: handedness, up axis, units, row/column vectors, matrix memory layout, multiplication order, angle units, and quaternion order.
3. Name transforms by direction, such as local_to_world and world_to_view.
4. Compose transforms in one place and cache composed matrices when reused.
5. Use inverse transforms to move queries into simpler spaces, especially for picking, SDFs, fields, and object-local collision.
6. Keep camera construction explicit: position, target or forward vector, up vector, field of view, aspect ratio, near/far planes.
7. Verify with round-trip tests and debug axes before tuning gameplay behavior.

Design Rules

• Treat transforms as first-class data, not hidden side effects in helper methods.
• Prefer one canonical transform chain for rendering and gameplay. Add adapters at engine or asset boundaries.
• Use homogeneous coordinates when translation, projection, and matrix composition must live in one pipeline.
• Use affine transforms for ordinary rotation, translation, scale, and shear.
• Use projective transforms when perspective, projection, or planar warping is part of the problem.
• Apply the inverse transform to an SDF or field input instead of rewriting the field's formula for every object transform.
• Transform normals with the inverse transpose when nonuniform scale or shear