Scale and vertical position as the parameters of sprites

game.ts

@@ -536,6 +536,8 @@ function displaySwapBackImageData(display: Display) {
 export interface Sprite {
     imageData: ImageData;
     position: Vector2;
+    z: number;
+    scale: number;
 }
 
 function renderSprites(display: Display, player: Player, sprites: Array<Sprite>) {
@@ -560,15 +562,13 @@ function renderSprites(display: Display, player: Player, sprites: Array<Sprite>)
         const cy = display.backImageData.height*0.5;
         const pdist = sprite.position.clone().sub(player.position).dot(dir);
         if (pdist < NEAR_CLIPPING_PLANE) continue; // TODO: I'm not sure if this check is necessary considering the `spl <= NEAR_CLIPPING_PLANE` above
-        // TODO: add an ability to positiion the sprites vertically
-        // TODO: make the scale of the sprite a parameter configurable per sprite
-        const spriteScale = 0.5;
-        const spriteSize = display.backImageData.height/pdist*spriteScale;
+        const maxSpriteSize = display.backImageData.height/pdist;
+        const spriteSize = maxSpriteSize*sprite.scale;
         const x1 = Math.floor(cx - spriteSize*0.5);
         const x2 = Math.floor(x1 + spriteSize - 1);
         const bx1 = Math.max(0, x1);
         const bx2 = Math.min(display.backImageData.width-1, x2);
-        const y1 = Math.floor(cy - spriteSize*0.5);
+        const y1 = Math.floor(cy + maxSpriteSize*0.5 - maxSpriteSize*sprite.z);
         const y2 = Math.floor(y1 + spriteSize - 1);
         const by1 = Math.max(0, y1);
         const by2 = Math.min(display.backImageData.height-1, y2);

index.ts

@@ -37,20 +37,24 @@ async function loadImageData(url: string): Promise<ImageData> {
 
     let game = await import("./game.js");
     const scene = game.createScene([
-        [ null, null, wall, wall, null, null, null],
+        [ null, null, wall, wall, wall, null, null],
         [ null, null, null, null, null, null, null],
         [ wall, null, null, null, null, null, null],
         [ wall,  null, null, null, null, null, null],
-        [ null],
+        [ wall],
         [  null,  null, null, null, null, null, null],
         [  null,  null, null, null, null, null, null],
     ]);
 
+    const KEY_SCALE = 0.4;
+    const KEY_Z = KEY_SCALE;
     const sprites = [
         {
             imageData: key,
             position: new game.Vector2(1.5, 1.5),
-        }
+            z: KEY_Z,
+            scale: KEY_SCALE
+        },
     ];
 
     const player = game.createPlayer(