draw light instead of shadows

src/util/useLightMap.ts

@@ -12,10 +12,11 @@ export default function useLightMap(
 ) {
   const W = ((STAGE_WIDTH + 2) * BLOCK_SIZE)
   const H = ((STAGE_HEIGHT + 2) * BLOCK_SIZE)
+  const B = BLOCK_SIZE - 4 // no idea why there is a difference, but it is 4px
 
-  const playerX = (W - BLOCK_SIZE) / 2 + BLOCK_SIZE / 4
-  const playerY = H / 2 - BLOCK_SIZE / 2
-  const playerLightSize = BLOCK_SIZE * 1.8
+  const playerX = (W - B) / 2 + B / 4
+  const playerY = H / 2 - B / 2
+  const playerLightSize = B * 1.8
 
   function getAmbientLightColor() {
     const t = time.value
@@ -45,7 +46,7 @@ export default function useLightMap(
       playerX - tx.value, playerY - ty.value, playerLightSize * sizeMul
     )
 
-    // Add three color stops
+    // Add color stops: white in the center to transparent white
     playerLight.addColorStop(0.0, "#FFFF");
     playerLight.addColorStop(1, "#FFF0");
 
@@ -58,12 +59,12 @@ export default function useLightMap(
     const barrier = lightBarrier.value
 
     ctx.fillStyle = '#000A'
-    for (let col = 0; col < W / BLOCK_SIZE; col++) {
-      const level = (barrier[col] - y.value) * BLOCK_SIZE
-      const sw = BLOCK_SIZE * 0.935
+    for (let col = 0; col < W / B; col++) {
+      const level = (barrier[col] - y.value) * B
+      const sw = B
       const sh = H - level
       const sx = col * sw
-      const sy = level * 0.995
+      const sy = level
 
       ctx.fillRect(sx, sy, sw, sh)
       ctx.fillRect(sx, sy + 20, sw, sh)
@@ -71,11 +72,51 @@ export default function useLightMap(
     }
   }
 
+  function drawLights() {
+    // used for everything above ground
+    const ambientLight = getAmbientLightColor()
+    const reflectedLight = ambientLight.slice(0, -1) + ', 50%)'
+    const surroundingLight = ambientLight.slice(-2)
+    const barrier = lightBarrier.value
+    // make light columns wider to illuminate surrounding blocks
+    const extra = Math.floor(B / 2)
+
+    ctx.fillStyle = ambientLight
+    for (let col = 0; col < W / B; col++) {
+      const level = (barrier[col] - y.value) * B
+      const sw = B
+      const sh = level
+      const sx = col * sw
+      const sy = 0
+
+      ctx.fillRect(sx, sy, sw, sh)
+    }
+
+    ctx.fillStyle = reflectedLight
+    for (let col = 0; col < W / B; col+=2) {
+      const level = (barrier[col] - y.value) * B
+      const sw = B
+      const sh = level
+      const sx = col * sw
+      const sy = 0
+
+      ctx.fillRect(sx - extra, sy - extra, sw + extra * 2, sh + extra * 2)
+    }
+
+    // TODO: draw light for candles and torches
+  }
+
   return function update() {
-    ctx.fillStyle = getAmbientLightColor()
+    // first, throw the world in complete darkness
+    ctx.fillStyle = '#000'
     ctx.fillRect(0, 0, W, H)
-    // TODO: switch from drawing shadows to drawing lights
-    drawShadows()
+
+    // second, find and bring light into the world
+    drawLights()
+
+    // finally, draw the players light
+    // with a size multiplicator which might be later used to
+    // simulate greater illumination with candles or torches
     drawPlayerLight(1)
   }
 }