new gem on worldgen

src/net/torvald/terrarum/modulebasegame/ExplosionManager.kt

@@ -0,0 +1,80 @@
+package net.torvald.terrarum.modulebasegame
+
+import net.torvald.terrarum.gameworld.BlockLayerI16
+import net.torvald.terrarum.gameworld.GameWorld
+import net.torvald.terrarum.gameworld.getOffset
+import net.torvald.terrarum.tryDispose
+import net.torvald.unsafe.UnsafeHelper
+
+/**
+ * Created by minjaesong on 2024-02-13.
+ */
+object ExplosionManager {
+
+    private const val CALC_RADIUS = 127
+    private const val CALC_WIDTH = CALC_RADIUS * 2 + 1
+
+    fun goBoom(world: GameWorld, tx: Int, ty: Int, power: Float) {
+        // create a copy of the tilemap
+        val tilemap = BlockLayerI16(CALC_WIDTH, CALC_WIDTH)
+
+        // fill in the tilemap copy
+        for (line in 0 until CALC_WIDTH) {
+            memcpyFromWorld(world, tx - CALC_RADIUS, ty - CALC_RADIUS, line, tilemap)
+        }
+
+        createExplosionWorker(tilemap, tx, ty, power, world).start()
+    }
+
+    private fun memcpyFromWorld(world: GameWorld, xStart: Int, yStart: Int, yOff: Int, out: BlockLayerI16) {
+        // if the bounding box must wrap around
+        if (xStart > world.width - CALC_RADIUS) {
+            val lenLeft = world.width - xStart
+            val lenRight = CALC_WIDTH - lenLeft
+
+            UnsafeHelper.memcpy(
+                world.layerTerrain.ptr,
+                world.layerTerrain.getOffset(xStart, yStart + yOff),
+                out.ptr,
+                out.getOffset(0, yOff),
+                world.layerTerrain.bytesPerBlock * lenLeft
+            )
+            UnsafeHelper.memcpy(
+                world.layerTerrain.ptr,
+                world.layerTerrain.getOffset(0, yStart + yOff),
+                out.ptr,
+                out.getOffset(lenLeft, yOff),
+                world.layerTerrain.bytesPerBlock * lenRight
+            )
+        }
+        else {
+            UnsafeHelper.memcpy(
+                world.layerTerrain.ptr,
+                world.layerTerrain.getOffset(xStart, yStart + yOff),
+                out.ptr,
+                out.getOffset(0, yOff),
+                world.layerTerrain.bytesPerBlock * CALC_WIDTH
+            )
+        }
+    }
+
+    /**
+     * @param tilemap a portion copy of the tilemap from the world, centred to the explosive
+     * @param tx tilewise centre-x of the explosive
+     * @param ty tilewise centre-y of the explosive
+     * @param outWorld world object to write the result to
+     */
+    private fun createExplosionWorker(tilemap: BlockLayerI16, tx: Int, ty: Int, power: Float, outWorld: GameWorld): Thread {
+        return Thread {
+            // simulate explosion like lightmaprenderer
+
+
+            // write to the world
+
+
+            // dispose of the tilemap copy
+            tilemap.tryDispose()
+        }
+    }
+
+}