Implement fade in wasm

tryjumping · Dec 20, 2017 · 4eff11c · 4eff11c
1 parent 08b2ee5
commit 4eff11c
Show file tree

Hide file tree

Showing 2 changed files with 20 additions and 2 deletions.
diff --git a/dose-response.js b/dose-response.js
@@ -138,7 +138,13 @@ fetch('target/wasm32-unknown-unknown/release/dose-response.wasm')
           let g = memory[i + 4];
           let b = memory[i + 5];
 
-          if(glyph === null) {
+          // NOTE: (255, 255) position means fade
+          if(x == 255 && y == 255) {
+            // NOTE: alpha is stored in the glyph position
+            let alpha = memory[i + 2] / 255;  // convert the "alpha" to <0, 1>
+            ctx.fillStyle = `rgba(${r}, ${g}, ${b}, ${alpha})`;
+            ctx.fillRect(0, 0, width * squareSize, height * squareSize);
+          } else if(glyph === null) {
             ctx.fillStyle = `rgb(${r},${g},${b})`;
             ctx.fillRect(x * squareSize, y * squareSize, squareSize, squareSize);
           } else {

diff --git a/src/main.rs b/src/main.rs
@@ -464,7 +464,19 @@ pub fn update(state_ptr: *mut State) {
                 js_drawcalls.push(color.b);
             }
 
-            _ => {}  // TODO
+            &engine::Draw::Fade(fade, color) => {
+                assert!(fade >= 0.0);
+                assert!(fade <= 1.0);
+                // NOTE: (255, 255) position means fade
+                js_drawcalls.push(255);
+                js_drawcalls.push(255);
+                // NOTE: fade value/alpha is stored in the glyph
+                js_drawcalls.push(((1.0 - fade) * 255.0) as u8);
+                js_drawcalls.push(color.r);
+                js_drawcalls.push(color.g);
+                js_drawcalls.push(color.b);
+            }
+
         }
     }