Folder structure

src/weapons.js

@@ -0,0 +1,163 @@
+import {drawCircle, plot} from './gfx.js';
+import {clipTerrain} from './terrain.js';
+import {within, cycle, random, randomInt} from './math.js';
+import {createOsc, audio} from './sound.js';
+import {PLAYER_TANK_BOUNDING_RADIUS} from './constants.js';
+
+export function drawExplosion(ctx, x, y, r) {
+  const color = 255 - (16 * (r % 16));
+  drawCircle(ctx, x, y, r, `rgb(${color}, 0, 0)`);
+}
+
+export function drawDirt(ctx, x, y, r, c) {
+  drawCircle(ctx, x, y, r, c);
+}
+
+export const EXPLOSION_TYPES = {
+  tracer: {
+    create(spec, x, y) {
+      return {type:'tracer'};
+    },
+    update(explosion) {},
+    draw(explosion, foreground) {},
+    stop(explosion) {},
+    clip(explosion, terrain) {},
+    damage(explosion, player) {}
+  },
+  blast: {
+    create(spec, x, y) {
+      const {r} = spec;
+      const osc = createOsc();
+      osc.start();
+      return {type:'blast', x, y, r, cr:0, osc};
+    },
+    update(explosion) {
+      return ++explosion.cr < explosion.r;
+    },
+    draw(explosion, foreground) {
+      const {x, y, cr, osc} = explosion;
+      const f = cycle(explosion.cr, 6) % 2 === 0 ? 220 : 440;
+      osc.frequency.setValueAtTime(f, audio.currentTime);
+      drawExplosion(foreground, x, y, cr);
+    },
+    stop(explosion) {
+      const {osc} = explosion;
+      osc.stop();
+    },
+    clip(explosion, terrain) {
+      const {x, y, cr} = explosion;
+      clipTerrain(terrain, (ctx) => drawExplosion(ctx, x, y, cr));
+    },
+    damage(explosion, player) {
+      if (within(explosion.x, explosion.y, player.x, player.y, explosion.r)) {
+        return 100;
+      } else if (
+        within(explosion.x, explosion.y, player.x-PLAYER_TANK_BOUNDING_RADIUS, player.y, explosion.r) ||
+        within(explosion.x, explosion.y, player.x+PLAYER_TANK_BOUNDING_RADIUS, player.y, explosion.r)
+      ) {
+        return 50;
+      }
+    }
+  },
+  dirt: {
+    create(spec, x, y) {
+      const {r} = spec;
+      const osc = createOsc();
+      osc.start();
+      return {type:'dirt', x, y, r, cr:0, osc};
+    },
+    stop(explosion) {
+      const {osc} = explosion;
+      osc.stop();
+    },
+    update(explosion) {
+      return ++explosion.cr < explosion.r;
+    },
+    draw(explosion, foreground, terrain) {
+      const {x, y, cr, osc} = explosion;
+      const f = explosion.cr % 2 === 0 ? 220 + explosion.cr : 0;
+      osc.frequency.setValueAtTime(f, audio.currentTime);
+      osc.frequency.setValueAtTime(0, audio.currentTime+0.1);
+      drawDirt(foreground, x, y, cr, terrain.color);
+    },
+    clip(explosion, terrain) {
+      const {x, y, cr} = explosion;
+      drawDirt(terrain, x, y, cr);
+    },
+    damage(explosion, player) {}
+  },
+  digBomb: {
+    create(spec, x, y) {
+      const {r} = spec;
+      const osc = createOsc();
+      osc.start();
+      return {type:'digBomb', x, y, r, cr:0, osc};
+    },
+    stop(explosion) {
+      const {osc} = explosion;
+      osc.stop();
+    },
+    update(explosion) {
+      return ++explosion.cr < explosion.r;
+    },
+    draw(explosion, foreground, terrain) {
+      const {x, y, cr, osc} = explosion;
+      const f = explosion.cr % 2 === 0 ? 440 - explosion.cr : 0;
+      osc.frequency.setValueAtTime(f, audio.currentTime);
+      osc.frequency.setValueAtTime(0, audio.currentTime+0.1);
+      drawDirt(foreground, x, y, cr, 'brown');
+    },
+    clip(explosion, terrain) {
+      const {x, y, cr} = explosion;
+      clipTerrain(terrain, (ctx) => drawDirt(ctx, x, y, cr));
+    },
+    damage(explosion, player) {}
+  },
+  dirtCone: {
+    create(spec, x, y) {
+      const {r} = spec;
+      const pattern = [];
+      const osc = createOsc();
+      osc.start();
+      return {type:'dirtCone', x, y, r, cr:0, osc, pattern};
+    },
+    stop(explosion) {
+      const {osc} = explosion;
+      osc.stop();
+    },
+    update(explosion) {
+      return ++explosion.cr < explosion.r;
+    },
+    draw(explosion, foreground, terrain) {
+      const {x, y, cr, osc, pattern} = explosion;
+
+      let row = [];
+      for (let cx=0; cx<=1+cr*2; cx++) {
+        row.push(randomInt(0, 3) === 0);
+      }
+      pattern.push(row);
+
+      for (let cy=0; cy<pattern.length; cy++) {
+        const row = pattern[cy];
+        for (let cx=0; cx<row.length; cx++) {
+          if (row[cx]) plot(foreground, x-cy+cx, y-cy, terrain.color);
+        }
+      }
+
+      const f = explosion.cr % 2 === 0 ? 220 + explosion.cr : 0;
+      osc.frequency.setValueAtTime(f, audio.currentTime);
+      osc.frequency.setValueAtTime(0, audio.currentTime+0.1);
+    },
+    clip(explosion, terrain) {
+      const {x, y, pattern} = explosion;
+
+      for (let cy=0; cy<pattern.length; cy++) {
+        const row = pattern[cy];
+        for (let cx=0; cx<row.length; cx++) {
+          if (row[cx]) plot(terrain, x-cy+cx, y-cy, terrain.color);
+        }
+      }
+    },
+    damage(explosion, player) {}
+  },
+}