Make VoxelBrush::transform() into rotate().

This accounts for all the actual uses, and avoids confusion between
points and cubes.

CHANGELOG.md

@@ -20,6 +20,8 @@
         - `math::GridMatrix::decompose()`
         - `space::Space::draw_target()`
         - `space::SpaceTransaction::draw_target()`
+    - `drawing::VoxelBrush::transform()` is renamed to `rotate()` and only accepts a rotation.
+      This avoids confusion between points in space and cube-identifying coordinates.
 
 ### Removed
 

all-is-cubes-content/src/dungeon/demo_dungeon.rs

@@ -660,7 +660,7 @@ pub async fn install_dungeon_blocks(
                     space_from_image(include_image!("floor.png"), GridRotation::RXZY, |pixel| {
                         let block = Block::from(Rgba::from_srgb8(pixel.0));
                         VoxelBrush::with_thickness(block, 0..resolution.into())
-                            .transform(GridRotation::RXZY.to_rotation_matrix())
+                            .rotate(GridRotation::RXZY)
                     })?;
                 Block::builder()
                     .display_name("Floor Tile")

all-is-cubes-content/src/exhibits.rs

@@ -1072,7 +1072,7 @@ async fn IMAGES(_: &Exhibit, universe: &mut Universe) {
             let image::Rgba([r, g, b, a]) = pixel;
             if (r > b || g > b) && a > 0 {
                 let block = Block::from(Rgba::from_srgb8(pixel.0));
-                VoxelBrush::with_thickness(block, 0..2).transform(rotation.to_rotation_matrix())
+                VoxelBrush::with_thickness(block, 0..2).rotate(rotation)
             } else {
                 default_srgb(pixel)
             }

all-is-cubes/src/drawing.rs

@@ -15,7 +15,7 @@
 //!     and rectangles have inclusive upper bounds (whereas our [`GridAab`]s have
 //!     exclusive upper bounds).
 
-use cgmath::{EuclideanSpace as _, Transform as _};
+use cgmath::EuclideanSpace as _;
 use embedded_graphics::geometry::{Dimensions, Point, Size};
 use embedded_graphics::pixelcolor::{PixelColor, Rgb888, RgbColor};
 use embedded_graphics::prelude::{DrawTarget, Drawable, Pixel};
@@ -29,8 +29,8 @@ pub use embedded_graphics;
 
 use crate::block::{space_to_blocks, Block, BlockAttributes, Resolution};
 use crate::math::{
-    Face6, FaceMap, GridAab, GridCoordinate, GridMatrix, GridPoint, GridRotation, GridVector,
-    Gridgid, Rgb, Rgba,
+    Face6, FaceMap, GridAab, GridCoordinate, GridPoint, GridRotation, GridVector, Gridgid, Rgb,
+    Rgba,
 };
 use crate::space::{SetCubeError, Space, SpacePhysics, SpaceTransaction};
 use crate::universe::Universe;
@@ -365,12 +365,11 @@ impl<'a> VoxelBrush<'a> {
         self
     }
 
-    /// Apply the given transform to the position of each block.
+    /// Apply the given rotation (about the no-offset block) to the position of each block.
     #[must_use]
-    pub fn transform(mut self, transform: GridMatrix) -> Self {
+    pub fn rotate(mut self, rotation: GridRotation) -> Self {
         for (block_offset, _) in self.0.iter_mut() {
-            // TODO: shouldn't this be transform_cube?
-            *block_offset = transform.transform_point(*block_offset);
+            *block_offset = GridPoint::from_vec(rotation.transform_vector(block_offset.to_vec()));
         }
         self
     }