khora_data/ecs/components/
transform.rs

1// Copyright 2025 eraflo
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15use khora_core::math::{Mat4, Quaternion, Vec3};
16
17use crate::ecs::Component;
18
19/// A component that describes an entity's position, rotation, and scale
20/// relative to its `Parent`. If the entity has no `Parent`, this is relative
21/// to the world origin.
22///
23/// This is the component that users and other systems should modify. A dedicated
24/// transform propagation system will use this component's value to calculate
25/// the final `GlobalTransform`.
26#[derive(Debug, Clone, Copy, PartialEq)]
27pub struct Transform {
28    /// The translation (position) of the entity.
29    pub translation: Vec3,
30    /// The rotation of the entity, represented as a quaternion.
31    pub rotation: Quaternion,
32    /// The scale of the entity.
33    pub scale: Vec3,
34}
35
36impl Component for Transform {}
37
38impl Transform {
39    /// Creates a new `Transform` with a given translation, rotation, and scale.
40    pub fn new(translation: Vec3, rotation: Quaternion, scale: Vec3) -> Self {
41        Self {
42            translation,
43            rotation,
44            scale,
45        }
46    }
47
48    /// Creates a new identity `Transform`, with no translation, rotation, or scaling.
49    /// This represents the origin.
50    pub fn identity() -> Self {
51        Self {
52            translation: Vec3::ZERO,
53            rotation: Quaternion::IDENTITY,
54            scale: Vec3::ONE,
55        }
56    }
57
58    /// Calculates the `Mat4` transformation matrix from this component's
59    /// translation, rotation, and scale.
60    ///
61    /// The final matrix is calculated in the standard `Scale -> Rotate -> Translate` order.
62    pub fn to_mat4(&self) -> Mat4 {
63        // T * R * S
64        Mat4::from_translation(self.translation)
65            * Mat4::from_quat(self.rotation)
66            * Mat4::from_scale(self.scale)
67    }
68}
69
70impl Default for Transform {
71    /// Returns the identity `Transform`.
72    fn default() -> Self {
73        Self::identity()
74    }
75}
khora_data/ecs/components/transform.rs

khora_data/ecs/components/
transform.rs
