Precise partial tank collision

src/constants.js

@@ -74,7 +74,8 @@ export const PLAYER_INITIAL_POWER = 300;
 export const PLAYER_FALL_DAMAGE_HEIGHT = 50;
 export const PLAYER_FALL_DAMAGE_FACTOR = 3;
 export const PLAYER_EXPLOSION_PARTICLE_POWER = 500;
-export const PLAYER_TANK_BOUNDING_RADIUS = 3;
+export const PLAYER_TANK_BOUNDING_RADIUS = 4;
+export const PLAYER_TANK_Y_FOOTPRINT = -2;
 export const PLAYER_ANGLE_INCREMENT = 1;
 export const PLAYER_ANGLE_FAST_INCREMENT = 3;
 export const PLAYER_POWER_INCREMENT = 1;

src/main.js

@@ -1,13 +1,13 @@
-import {H, PROJECTILE_MAX_SOUND_FREQUENCY, MAX_WIND, PROJECTILE_MIN_SOUND_FREQUENCY, PLAYER_COLORS, PLAYER_INITIAL_POWER, PROJECTILE_POWER_REDUCTION_FACTOR, W, Z, PROJECTILE_ITERATIONS_PER_FRAME, PROJECTILE_ITERATION_PROGRESS, PLAYER_MAX_ENERGY, PLAYER_ENERGY_POWER_MULTIPLIER, PLAYER_FALL_DAMAGE_FACTOR, PLAYER_FALL_DAMAGE_HEIGHT, PARTICLE_AMOUNT, PROJECTILE_WIND_REDUCTION_FACTOR, PARTICLE_POWER_REDUCTION_FACTOR, PARTICLE_WIND_REDUCTION_FACTOR, PARTICLE_MIN_POWER_FACTOR, PARTICLE_MAX_POWER_FACTOR, PARTICLE_MIN_LIFETIME, PARTICLE_TIME_FACTOR, PLAYER_EXPLOSION_PARTICLE_POWER, EXPLOSION_SHAKE_REDUCTION_FACTOR, MAX_EXPLOSION_SHAKE_FACTOR, TRAJECTORY_FADE_SPEED, PARTICLE_FADE_AMOUNT, TRAJECTORY_FLOAT_SPEED, PLAYER_TANK_BOUNDING_RADIUS, PLAYER_STARTING_WEAPONS, WEAPON_TYPES, DEATH_SPECS, PLAYER_ANGLE_INCREMENT, PLAYER_POWER_FAST_INCREMENT, PLAYER_POWER_INCREMENT, PLAYER_ANGLE_TICK_SOUND_INTERVAL, PLAYER_POWER_TICK_SOUND_INTERVAL, PLAYER_ANGLE_FAST_INCREMENT} from './constants.js';
-import {createCanvas, drawLine, drawRect, drawText, loop, plot, drawLineVirtual} from './gfx.js';
-import {key, afterKeyDelay} from './input.js';
-import {clamp, deg2rad, parable, randomInt, vec, wrap, random, within} from './math.js';
-import {createSky} from './sky.js';
-import {audio, createOsc, playTickSound, createAudioLoop} from './sound.js';
-import {collapseTerrain, createTerrain, isTerrain, landHeight, closestLand, clipTerrain} from './terrain.js';
-import {EXPLOSION_TYPES} from './weapons.js';
-import {sample} from './utils.js';
 import {AI_TYPES} from './ai.js';
+import {DEATH_SPECS, EXPLOSION_SHAKE_REDUCTION_FACTOR, H, MAX_EXPLOSION_SHAKE_FACTOR, MAX_WIND, PARTICLE_AMOUNT, PARTICLE_FADE_AMOUNT, PARTICLE_MAX_POWER_FACTOR, PARTICLE_MIN_LIFETIME, PARTICLE_MIN_POWER_FACTOR, PARTICLE_POWER_REDUCTION_FACTOR, PARTICLE_TIME_FACTOR, PARTICLE_WIND_REDUCTION_FACTOR, PLAYER_ANGLE_FAST_INCREMENT, PLAYER_ANGLE_INCREMENT, PLAYER_ANGLE_TICK_SOUND_INTERVAL, PLAYER_COLORS, PLAYER_ENERGY_POWER_MULTIPLIER, PLAYER_EXPLOSION_PARTICLE_POWER, PLAYER_FALL_DAMAGE_FACTOR, PLAYER_FALL_DAMAGE_HEIGHT, PLAYER_INITIAL_POWER, PLAYER_MAX_ENERGY, PLAYER_POWER_FAST_INCREMENT, PLAYER_POWER_INCREMENT, PLAYER_POWER_TICK_SOUND_INTERVAL, PLAYER_STARTING_WEAPONS, PLAYER_TANK_BOUNDING_RADIUS, PLAYER_TANK_Y_FOOTPRINT, PROJECTILE_ITERATIONS_PER_FRAME, PROJECTILE_ITERATION_PROGRESS, PROJECTILE_MAX_SOUND_FREQUENCY, PROJECTILE_MIN_SOUND_FREQUENCY, PROJECTILE_POWER_REDUCTION_FACTOR, PROJECTILE_WIND_REDUCTION_FACTOR, TRAJECTORY_FADE_SPEED, TRAJECTORY_FLOAT_SPEED, W, WEAPON_TYPES, Z} from './constants.js';
+import {createCanvas, drawLine, drawLineVirtual, drawRect, drawText, loop, plot} from './gfx.js';
+import {afterKeyDelay, key} from './input.js';
+import {clamp, deg2rad, distance, parable, random, randomInt, vec, wrap} from './math.js';
+import {createSky} from './sky.js';
+import {audio, createOsc, playTickSound} from './sound.js';
+import {clipTerrain, closestLand, collapseTerrain, createTerrain, isTerrain, landHeight} from './terrain.js';
+import {sample} from './utils.js';
+import {EXPLOSION_TYPES} from './weapons.js';
 
 
 let state = 'start-game';
@@ -341,7 +341,11 @@ function updateParticles() {
 function isTank(x, y) {
   for (let player of players) {
     if (player.dead) continue;
-    if (within(x, y, player.x, player.y, PLAYER_TANK_BOUNDING_RADIUS)) {
+
+    if (
+      distance(x, y, player.x, player.y+PLAYER_TANK_Y_FOOTPRINT) <=
+      PLAYER_TANK_BOUNDING_RADIUS
+    ) {
       return true;
     }
   }

src/math.js

@@ -5,8 +5,7 @@ export function index2coords(width, i) {
 }
 
 export function coords2index(width, x, y) {
-  x = Math.round(x);
-  y = Math.round(y);
+  x = Math.round(x); y = Math.round(y);
   width = Math.round(width);
   return y * width + x;
 }
@@ -35,8 +34,15 @@ export function cycle(x, d) {
   return Math.floor(x / d);
 }
 
-export function within(x, y, tx, ty, r) {
-  return Math.abs(x-tx) < r && Math.abs(y-ty) < r;
+export function diagonal(a, b) {
+  return Math.sqrt(a**2 + b**2);
+}
+
+export function distance(x1, y1, x2, y2) {
+  return diagonal(
+    Math.abs(x2-x1),
+    Math.abs(y2-y1),
+  );
 }
 
 export function parable(t, x, y, a, v, w=0, g=9.8) {

src/weapons.js

@@ -1,8 +1,8 @@
+import {PLAYER_TANK_BOUNDING_RADIUS, PLAYER_TANK_Y_FOOTPRINT} from './constants.js';
 import {drawCircle, plot} from './gfx.js';
+import {clamp, cycle, distance, randomInt} from './math.js';
+import {audio, createOsc} from './sound.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));
@@ -49,13 +49,11 @@ export const EXPLOSION_TYPES = {
       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;
+      const {x, y, r} = explosion;
+      const dist = distance(x, y, player.x, player.y+PLAYER_TANK_Y_FOOTPRINT);
+      const tolerance = clamp(0, dist - r, Infinity);
+      if (tolerance <= PLAYER_TANK_BOUNDING_RADIUS) {
+        return Math.round(100 * (1 - tolerance / (PLAYER_TANK_BOUNDING_RADIUS+1)));
       }
     }
   },