rotation of backgrounds

Cargo.toml

@@ -24,7 +24,7 @@ dunce = "1.0.4"
 path-slash = "0.2.1"
 serde = {version = "1.0.181", features = ["derive"]}
 postcard = {version = "1.0.6", features = ["alloc"]}
-#rayon = "1.7.0"
+rayon = "1.7.0"
 
 [profile.release-dani]
 inherits = "release"

examples/basic/main.rs

@@ -1,14 +1,26 @@
 use glam::IVec2;
-use gsa::{run, Gsa, FACE_DOWN};
+use gsa::{run, Gsa, FACE_DOWN, SCREEN_WIDTH, SCREEN_HEIGHT, SCREEN_MIDDLE, FACE_LEFT, FACE_RIGHT};
 
 struct Game {}
 
 fn init(gsa: &mut Gsa) -> Game {
-    gsa.bg[0].fill(0x0101);
+    gsa.bg[0].fill(0x7101);
     //gsa.write_string(IVec2::ONE, "Hello world nyaa~");
+    gsa.bg[0].rot = 10;
+    gsa.bg[0].origin = SCREEN_MIDDLE;
+    gsa.bg[0].scroll = SCREEN_MIDDLE;
     Game {}
 }
 
-fn update(_game: &mut Game, gsa: &mut Gsa) {}
+fn update(_game: &mut Game, gsa: &mut Gsa) {
+    if gsa.button_down(FACE_LEFT) {
+	gsa.bg[0].rot = gsa.bg[0].rot.wrapping_add(1);
+    }
+    if gsa.button_down(FACE_RIGHT) {
+	gsa.bg[0].rot = gsa.bg[0].rot.wrapping_sub(1);
+    }
+    //gsa.bg[0].scroll.x = (gsa.bg[0].scroll.x + 10) % 300;
+    gsa.bg[0].scroll += gsa.input_dir();
+}
 
 run!(init, update);

src/background.rs

@@ -7,6 +7,10 @@ pub struct Background {
     pub tiles: Vec<Vec<u16>>,
     /// Camera scroll (negative draw offset) for rendering
     pub scroll: IVec2,
+    /// Rotation, 0-255 equals one full turn
+    pub rot: u8,
+    /// Origin (used for rotation and scroll and such)
+    pub origin: IVec2,
     /// Size (used for rendering)
     pub size: IVec2,
     /// Are tiles indices half-tile indices?
@@ -25,6 +29,8 @@ impl Default for Background {
             half_tile: false,
             active: true,
             size: IVec2 { x: 19, y: 11 },
+	    origin: IVec2::ZERO,
+	    rot: 0
         }
     }
 }

src/gsa_render_to_screen.rs

@@ -1,11 +1,11 @@
-use std::usize;
-//use rayon::prelude::*;
+use std::{usize, f32::consts::PI};
+use rayon::prelude::*;
 
 use crate::{
     Background, Gsa, Rgb, EMPTY_TILE, HALF_TILE_SIZE, MAX_BACKGROUNDS, TILESET_SIZE, TILE_SIZE,
     TRANSPARENT,
 };
-use glam::IVec2;
+use glam::{IVec2, Mat2, Vec2};
 use softbuffer::Buffer;
 
 fn draw_tile(
@@ -78,26 +78,45 @@ fn render_bg2(target: &mut [u8], map: &Background, tileset: &[u8], screen_size:
     } else {
         TILE_SIZE
     } as i32;
+
+    let a = map.rot as f32 / 256.0 * PI * 2.0;
+    
+    
+    let du = glam::Vec2::new(a.cos(), a.sin());
+    let dv = glam::Vec2::new(-a.sin(), a.cos());
+    let duv = Mat2::from_cols(du, dv);
+
     //target.par_chunks_exact_mut(screen_size.x as usize).enumerate().for_each({|(screeny, row)|
-    target.chunks_exact_mut(screen_size.x as usize).enumerate().for_each({|(screeny, row)|
+    target
+        .chunks_exact_mut(screen_size.x as usize)
+        .enumerate()
+        .for_each({
+            |(screeny, row)| {
                 for screenx in 0..screen_size.x {
-            let x = screenx + map.scroll.x;
-            let y = screeny as i32 + map.scroll.y;
-            let tilex = x / tilesize;
-            let tiley = y / tilesize;
-            let pixx = x % tilesize;
-            let pixy = y % tilesize;
-            let tile = if tilex >= 0 && tiley >= 0 && tilex < map.size.x && tiley < map.size.y {
+		    let screen = duv * Vec2::new(screenx as f32  - map.origin.x as f32, screeny as f32  - map.origin.y as f32);
+                    let x = screen.x.floor() as i32 + map.scroll.x;
+                    let y = screen.y.floor() as i32 + map.scroll.y;
+                    let tilex = x.div_euclid(tilesize);
+                    let tiley = y.div_euclid(tilesize);
+		    //println!("{},{}", x,tilex);
+		    //assert!(tilex >= 0);
+		    // the addition is there because otherwise x might be below 0
+		    // which messes with the modulo
+                    let pixx = (x+tilesize) % tilesize;
+                    let pixy = (y+tilesize) % tilesize;
+                    let tile =
+                        if tilex >= 0 && tiley >= 0 && tilex < map.size.x && tiley < map.size.y {
                             map.tiles[tilex as usize][tiley as usize]
                         } else {
                             EMPTY_TILE
                         };
                     if tile != EMPTY_TILE {
-                let tilesetx = tile as usize % 0x100 * tilesize as usize + pixx as usize;
-                let tilesety = tile as usize / 0x100 * tilesize as usize + pixy as usize;
-		let p = tileset[tilesetx + tilesety * (TILESET_SIZE * TILE_SIZE)];
+                        let tilesetx = tile as i32 % 0x100 * tilesize + pixx;
+                        let tilesety = tile as i32 / 0x100 * tilesize + pixy;
+                        let p = tileset[tilesetx as usize + tilesety as usize * (TILESET_SIZE * TILE_SIZE)];
                         if p != TRANSPARENT {
-		    row[x as usize] = p;
+                            row[screenx as usize] = p;
+                        }
                     }
                 }
             }

src/lib.rs

@@ -50,6 +50,8 @@ mod sprite;
 mod tilemap;
 mod tileset;
 
+use glam::IVec2;
+
 pub use crate::background::*;
 pub use crate::buttons::*;
 pub use crate::gsa::*;
@@ -66,6 +68,12 @@ pub const SCREEN_WIDTH: usize = 304;
 /// Screen Height in pixels
 pub const SCREEN_HEIGHT: usize = 176;
 
+/// Screen size as vector (SCREEN_WIDTH,SCREEN_HEIGHT)
+pub const SCREEN_SIZE: IVec2 = IVec2{x: SCREEN_WIDTH as i32, y: SCREEN_HEIGHT as i32};
+
+/// Center of screen as vector
+pub const SCREEN_MIDDLE: IVec2 = IVec2{x: SCREEN_WIDTH as i32 / 2, y: SCREEN_HEIGHT as i32 / 2};
+
 /// X and y dimensions of maps in [Gsa::bgs]
 pub const BACKGROUND_MAX_SIZE: usize = 1024;
 

src/run.rs

@@ -47,7 +47,7 @@ pub fn run<TGame: 'static>(
 ) {
     let (tileset, palette) = load_tileset(image_data);
 
-    //rayon::ThreadPoolBuilder::new().num_threads(32).build_global().unwrap();
+    //rayon::ThreadPoolBuilder::new().num_threads(2).build_global().unwrap();
 
     let mut gsa = Gsa {
         sprite: [Sprite::default(); MAX_SPRITES],
@@ -100,7 +100,7 @@ pub fn run<TGame: 'static>(
     let mut last_second = Instant::now();
 
     let mut last_frame = last_second;
-    let target_frame_duration = Duration::from_secs(1).div_f64(60000.0);
+    let target_frame_duration = Duration::from_secs(1).div_f64(60.0);
 
     let mut scale = 1usize;
     let mut off_x = 0usize;