add bomb

src/combat_screen.zig

@@ -76,6 +76,13 @@ const Laser = struct {
     duration: Nanoseconds
 };
 
+const Bomb = struct {
+    kinetic: Kinetic,
+    size: f32,
+    explode_at: Nanoseconds,
+    explosion_radius: f32
+};
+
 const Enemy = struct {
     kinetic: Kinetic,
     speed: f32,
@@ -126,6 +133,7 @@ enemies: std.ArrayList(Enemy) = .empty,
 player: Player = .{},
 bullets: std.ArrayList(Bullet) = .empty,
 lasers: std.ArrayList(Laser) = .empty,
+bombs: std.ArrayList(Bomb) = .empty,
 
 pickups: std.ArrayList(Pickup) = .empty,
 next_pickup_spawn_at: Nanoseconds,
@@ -164,6 +172,7 @@ pub fn deinit(self: *CombatScreen) void {
     self.pickups.deinit(self.gpa);
     self.spawned_waves.deinit(self.gpa);
     self.lasers.deinit(self.gpa);
+    self.bombs.deinit(self.gpa);
 }
 
 pub fn spawnEnemy(self: *CombatScreen) !void {
@@ -360,6 +369,15 @@ pub fn tick(self: *CombatScreen, state: *State, frame: *Engine.Frame) !TickResul
                         });
                     },
                     .bomb => {
+                        try self.bombs.append(self.gpa, .{
+                            .kinetic = .{
+                                .pos = self.player.kinetic.pos,
+                                .vel = bullet_dir.multiplyScalar(800)
+                            },
+                            .size = 10,
+                            .explode_at = frame.time_ns + std.time.ns_per_s,
+                            .explosion_radius = 50
+                        });
                     },
                     .laser => {
                         try self.lasers.append(self.gpa, .{
@@ -400,7 +418,12 @@ pub fn tick(self: *CombatScreen, state: *State, frame: *Engine.Frame) !TickResul
         });
     }
 
-    for (self.lasers.items) |*laser| {
+    {
+        var index: usize = 0;
+        while (index < self.lasers.items.len) {
+            var destroy = false;
+            var laser = &self.lasers.items[index];
+
             const laser_length = 1000;
             const laser_line = Line{
                 .p0 = laser.origin,
@@ -415,12 +438,59 @@ pub fn tick(self: *CombatScreen, state: *State, frame: *Engine.Frame) !TickResul
                 }
             }
 
+            if (frame.time_ns > (laser.created_at + laser.duration)) {
+                destroy = true;
+            }
+
             frame.drawLine(
                 laser_line.p0,
                 laser_line.p1,
                 rgb(200, 20, 255),
                 laser.size
             );
+
+            if (destroy) {
+                _ = self.lasers.swapRemove(index);
+            } else {
+                index += 1;
+            }
+        }
+    }
+
+    {
+        var index: usize = 0;
+        while (index < self.bombs.items.len) {
+            var destroy = false;
+            var bomb = &self.bombs.items[index];
+            bomb.kinetic.update(dt, .{
+                .friction = 0.998
+            });
+
+            if (frame.time_ns >= bomb.explode_at) {
+                destroy = true;
+
+                for (self.enemies.items) |*enemy| {
+                    const enemy_rect = getCenteredRect(enemy.kinetic.pos, enemy.size);
+                    if (enemy_rect.checkCircleOverlap(bomb.kinetic.pos, bomb.explosion_radius)) {
+                        enemy.dead = true;
+                        frame.drawCircle(bomb.kinetic.pos, bomb.explosion_radius, rgb(200, 20, 20));
+                    }
+                }
+            }
+            frame.drawCircle(bomb.kinetic.pos, bomb.explosion_radius, rgba(200, 20, 20, 0.2));
+
+            const bomb_rect = getCenteredRect(bomb.kinetic.pos, bomb.size);
+            frame.drawRectangle(.{
+                .rect = bomb_rect,
+                .color = rgb(200, 20, 255)
+            });
+
+            if (destroy) {
+                _ = self.bombs.swapRemove(index);
+            } else {
+                index += 1;
+            }
+        }
     }
 
     for (self.enemies.items) |*enemy| {

src/engine/frame.zig

@@ -230,6 +230,16 @@ pub fn popScissor(self: *Frame) void {
     });
 }
 
+pub fn drawCircle(self: *Frame, center: Vec2, radius: f32, color: Vec4) void {
+    self.pushGraphicsCommand(.{
+        .draw_circle = .{
+            .center = center,
+            .radius = radius,
+            .color = color,
+        }
+    });
+}
+
 pub fn drawRectangle(self: *Frame, opts: GraphicsCommand.DrawRectangle) void {
     self.pushGraphicsCommand(.{ .draw_rectangle = opts });
 }

src/engine/graphics.zig

@@ -48,6 +48,12 @@ pub const Command = union(enum) {
         origin: Vec2 = .init(0, 0),
     };
 
+    pub const DrawCircle = struct {
+        center: Vec2,
+        radius: f32,
+        color: Vec4,
+    };
+
     set_scissor: Rect,
     draw_rectangle: DrawRectangle,
     draw_line: struct { pos1: Vec2, pos2: Vec2, color: Vec4, width: f32 },
@@ -60,6 +66,7 @@ pub const Command = union(enum) {
     },
     push_transformation: struct { translation: Vec2, scale: Vec2 },
     pop_transformation: void,
+    draw_circle: DrawCircle
 };
 
 const Texture = struct {
@@ -206,6 +213,25 @@ pub fn drawCommand(command: Command) void {
             font_context.setColor(color);
             font_context.drawText(opts.pos.x * font_resolution_scale.x, opts.pos.y * font_resolution_scale.y, opts.text);
         },
+        .draw_circle => |opts| {
+            sgl.beginTriangleStrip();
+            defer sgl.end();
+
+            const angle_step: f32 = std.math.pi * 2.0 / 32.0;
+
+            sgl.c4f(opts.color.x, opts.color.y, opts.color.z, opts.color.w);
+
+            sgl.v2f(opts.center.x, opts.center.y);
+            var angle: f32 = 0;
+            while (angle < std.math.pi * 2) {
+                const point_on_circle = Vec2.initAngle(angle).multiplyScalar(opts.radius).add(opts.center);
+                sgl.v2f(point_on_circle.x, point_on_circle.y);
+                sgl.v2f(opts.center.x, opts.center.y);
+
+                angle += angle_step;
+            }
+            sgl.v2f(opts.center.x + opts.radius, opts.center.y);
+        }
     }
 }
 

src/engine/math.zig

@@ -472,6 +472,43 @@ pub const Rect = struct {
         return left_overlap or right_overlap or top_overlap or bottom_overlap;
     }
 
+    pub fn checkCircleOverlap(self: Rect, circle_center: Vec2, circle_radius: f32) bool {
+        const cx = circle_center.x;
+        const cy = circle_center.y;
+        const rx = self.pos.x;
+        const ry = self.pos.y;
+        const rw = self.size.x;
+        const rh = self.size.y;
+
+        // temporary variables to set edges for testing
+        var testX = cx;
+        var testY = cy;
+
+        // which edge is closest?
+        if (cx < rx) {
+            testX = rx;      // test left edge
+        } else if (cx > rx+rw) {
+            testX = rx+rw;   // right edge
+        }
+
+        if (cy < ry) {
+            testY = ry;      // top edge
+        } else if (cy > ry+rh) {
+            testY = ry+rh;   // bottom edge
+        }
+
+        // get distance from closest edges
+        const distX = cx-testX;
+        const distY = cy-testY;
+        const distance = @sqrt( (distX*distX) + (distY*distY) );
+
+        // if the distance is less than the radius, collision!
+        if (distance <= circle_radius) {
+            return true;
+        }
+        return false;
+    }
+
     pub fn hasOverlap(lhs: Rect, rhs: Rect) bool {
         return (lhs.left() < rhs.right() and lhs.right() > rhs.left()) and
             (lhs.top() < rhs.bottom() and lhs.bottom() > rhs.top());