examples

commit 00c134357d45d84224f4fc126c921f12b2ea2b6f
parent f0b3d10ed4c48f7051f94d75737b337f786d6fd5
Author: Henry Wilson <henry@henryandlizzy.uk>
Date:   Sat,  2 Apr 2022 18:15:45 +0100

gl-asteroids: Add basic particle system

Diffstat:
M
src/gl-asteroids.cpp
 | 
43
++++++++++++++++++++++++++++++++++++++++---

1 file changed, 40 insertions(+), 3 deletions(-)
diff --git a/src/gl-asteroids.cpp b/src/gl-asteroids.cpp
@@ -125,7 +125,7 @@ struct physics
 		pos += vel * dt;
 		pos.x = wrap(pos.x, -1, 1);
 		pos.y = wrap(pos.y, -1, 1);
-		rot += ang_mom * dt; 
+		rot += ang_mom * dt;
 	}
 };
 
@@ -133,7 +133,7 @@ bool is_colliding(physics const& a, physics const& b)
 {
 	float len = a.scale + b.scale;
 	auto d = a.pos - b.pos;
-	
+
 	return d.x * d.x + d.y * d.y < len * len;
 }
 
@@ -168,7 +168,36 @@ struct entity
 	}
 };
 
-GLFWwindow* w;
+struct particle
+{
+	entity e;
+	float ttl;
+
+	static particle& make_particle(entity e, float ttl)
+	{
+		return particles.emplace_back(e, ttl);
+	}
+	static void move_all(float dt)
+	{
+		for (auto& p : particles)
+		{
+			p.ttl -= dt;
+			p.e.p.move(dt);
+		}
+		std::erase_if(particles, [](auto& p) { return p.ttl <= 0; });
+	}
+	static void draw_all()
+	{
+		for (auto& p : particles)
+			p.e.draw();
+	}
+private:
+	static std::vector<particle> particles;
+};
+
+std::vector<particle> particle::particles;
+
+static GLFWwindow* w;
 
 bool is_pressed(int key)
 {
@@ -258,6 +287,12 @@ int main(int argc, char* argv[])
 		{
 			float sr = sin(s.rot), cr = cos(s.rot);
 			s.vel += coord{sr, cr} * dt;
+
+			auto f = s;
+			f.ang_mom = 0;
+			f.vel = coord{sr, cr} * -0.5;
+			f.vel += coord{cr, -sr} * 0.2 * dis_p(gen);
+			particle::make_particle(entity(flame, f), 1);
 		}
 		glClearColor(0,0,0,1);
 		glClear(GL_COLOR_BUFFER_BIT);
@@ -267,6 +302,7 @@ int main(int argc, char* argv[])
 		for (auto& b : bullets)
 			b.p.move(dt);
 		s.move(dt);
+		particle::move_all(dt);
 
 		if(any_of(rocks.begin(), rocks.end(), [&s](auto& r) { return is_colliding(s, r.p); }))
 			glfwSetWindowShouldClose(w, 1);
@@ -300,6 +336,7 @@ int main(int argc, char* argv[])
 		bang:	continue;
 		}
 
+		particle::draw_all();
 		for (auto& r : rocks)
 			r.draw();
 		for (auto& b : bullets)