Skip rendering tiles that only contain sky.

chunky/src/java/se/llbit/chunky/renderer/PathTracingRenderer.java

@@ -66,6 +66,8 @@ public void render(DefaultRenderManager manager) throws InterruptedException {
     double halfWidth = fullWidth / (2.0 * fullHeight);
     double invHeight = 1.0 / fullHeight;
 
+    resetTiles(manager); // reset previously skipped tiles
+
     double[] sampleBuffer = scene.getSampleBuffer();
 
     while (scene.spp < scene.getTargetSpp()) {

chunky/src/java/se/llbit/chunky/renderer/PreviewRenderer.java

@@ -75,6 +75,8 @@ public void render(DefaultRenderManager manager) throws InterruptedException {
     int ty = (int) Math.floor(target.o.y + target.d.y * Ray.OFFSET);
     int tz = (int) Math.floor(target.o.z + target.d.z * Ray.OFFSET);
 
+    resetTiles(manager); // reset previously skipped tiles
+
     double[] sampleBuffer = scene.getSampleBuffer();
 
     for (int i = 0; i < 2; i++) {

chunky/src/java/se/llbit/chunky/renderer/TileBasedRenderer.java

@@ -43,6 +43,7 @@ public abstract class TileBasedRenderer implements Renderer {
   public static class RenderTile {
     public int x0, x1;
     public int y0, y1;
+    public boolean skip = false;
 
     public RenderTile(int x0, int x1, int y0, int y1) {
       this.x0 = x0;
@@ -67,7 +68,10 @@ public void setPostRender(BooleanSupplier callback) {
   protected void submitTiles(DefaultRenderManager manager, BiConsumer<WorkerState, IntIntPair> perPixel) {
     initTiles(manager);
 
-    cachedTiles.forEach(tile ->
+    cachedTiles.forEach(tile -> {
+        if (tile.skip) {
+          return;
+        }
         manager.pool.submit(worker -> {
           WorkerState state = new WorkerState();
           state.ray = new Ray();
@@ -82,7 +86,12 @@ protected void submitTiles(DefaultRenderManager manager, BiConsumer<WorkerState,
               perPixel.accept(state, pair);
             }
           }
-        })
+
+          if (!state.hit) {
+            tile.skip = true;
+          }
+        });
+      }
     );
   }
 
@@ -92,17 +101,21 @@ private void initTiles(DefaultRenderManager manager) {
     int width = scene.canvasConfig.getWidth();
     int height = scene.canvasConfig.getHeight();
 
-    if (prevWidth != width || prevHeight != height) {
+    if (prevWidth != width || prevHeight != height || cachedTiles.isEmpty()) {
       prevWidth = width;
       prevHeight = height;
       cachedTiles.clear();
 
       for (int i = 0; i < width; i += tileWidth) {
         for (int j = 0; j < height; j += tileWidth) {
           cachedTiles.add(new RenderTile(i, FastMath.min(i + tileWidth, width),
-              j, FastMath.min(j + tileWidth, height)));
+            j, FastMath.min(j + tileWidth, height)));
         }
       }
     }
   }
+
+  public void resetTiles(DefaultRenderManager manager) {
+    cachedTiles.clear();
+  }
 }

chunky/src/java/se/llbit/chunky/renderer/WorkerState.java

@@ -28,4 +28,5 @@ public class WorkerState {
   public Ray ray;
   public Vector4 attenuation = new Vector4();
   public Random random;
+  public boolean hit = false;
 }

chunky/src/java/se/llbit/chunky/renderer/scene/PathTracer.java

@@ -69,6 +69,7 @@ public static boolean pathTrace(Scene scene, Ray ray, WorkerState state,
         if (ray.getPrevMaterial().isWater()) {
           ray.color.set(0, 0, 0, 1);
           hit = true;
+          state.hit = true;
         } else if (ray.depth == 0) {
           // Direct sky hit.
           if (!scene.transparentSky()) {
@@ -81,11 +82,13 @@ public static boolean pathTrace(Scene scene, Ray ray, WorkerState state,
           scene.sky.getSkyColor(ray, true);
           addSkyFog(scene, ray, state, ox, od);
           hit = true;
+          state.hit = true;
         } else {
           // Indirect sky hit - diffuse color.
           scene.sky.getSkyColorDiffuseSun(ray, scene.getSunSamplingStrategy().isDiffuseSun());
           // Skip sky fog - likely not noticeable in diffuse reflection.
           hit = true;
+          state.hit = true;
         }
         break;
       }