2d boids example done

2026-09-13 00:52:08 -07:00
parent 4190ff847b
commit 6e2c6c0fc5
2 changed files with 4 additions and 191 deletions
@@ -91,7 +91,7 @@ class Boids2D : public sophia::Application {
        {{-BOID_LENGTH * 0.5f, BOID_WIDTH * 0.5f}, {1.0f, 1.0f, 1.0f}},
        {{-BOID_LENGTH * 0.5f, -BOID_WIDTH * 0.5f}, {1.0f, 1.0f, 1.0f}},
    };
-    boidMesh = createMesh(std::move(vertices), {});
+    boidMesh = assets().loadMesh(std::move(vertices), {});
  }

  void onUpdate(const sophia::FrameInfo& frameInfo) override {
@@ -1,200 +1,13 @@
-#include <cmath>
 #include <iostream>
-#include <random>
 #include <sophia/application.hpp>
-#include <sophia/event.hpp>
-#include <sophia/key_event.hpp>
-#include <stdexcept>
-#include <string>
-#include <vector>
-
-#define GLM_FORCE_RADIANS
-#define GLM_FORCE_DEPTH_ZERO_TO_ONE
-#include <glm/glm.hpp>
-#include <glm/gtc/constants.hpp>
-
-struct Boid {
-  glm::vec2 position;
-  glm::vec2 velocity;
-};
-
-constexpr uint32_t DEFAULT_NUMBER_OF_BOIDS = 25;

 class Testbed : public sophia::Application {
 public:
-  static constexpr float SCROLL_SPEED = 200.0f;
+  Testbed() : Application{{.width = 750, .height = 1000, .name = "Testbed"}} {}

-  // World is a fixed box independent of the camera; boids wrap at its edges.
-  static constexpr float WORLD_HALF_WIDTH = 375.0f;
-  static constexpr float WORLD_HALF_HEIGHT = 500.0f;
+  void onCreate() override { std::cout << "Testbed created" << std::endl; }

-  static constexpr float MAX_SPEED = 120.0f;
-  static constexpr float MAX_FORCE = 200.0f;
-  static constexpr float PERCEPTION_RADIUS = 150.0f;
-  static constexpr float SEPARATION_RADIUS = 40.0f;
-  static constexpr float ALIGNMENT_WEIGHT = 1.0f;
-  static constexpr float COHESION_WEIGHT = 1.0f;
-  static constexpr float SEPARATION_WEIGHT = 1.5f;
-
-  Testbed() : Application{{.width = 750, .height = 1000, .name = "Testbed"}} {
-    uint32_t numberOfBoids = DEFAULT_NUMBER_OF_BOIDS;
-    if (args.size() > 1) {
-      numberOfBoids = static_cast<uint32_t>(std::stoul(args[1]));
-    }
-    boids.resize(numberOfBoids);
-
-    sophia::EventSystem::get().addListener<sophia::KeyPressedEvent>(
-        [this](sophia::KeyPressedEvent& e) {
-          setScrollKeyHeld(e.getKeyCode(), true);
-        });
-    sophia::EventSystem::get().addListener<sophia::KeyReleasedEvent>(
-        [this](sophia::KeyReleasedEvent& e) {
-          setScrollKeyHeld(e.getKeyCode(), false);
-        });
-  }
-
-  void onCreate() override {
-    std::cout << "Testbed created" << std::endl;
-
-    std::mt19937 rng{std::random_device{}()};
-    std::uniform_real_distribution<float> posX{-WORLD_HALF_WIDTH,
-                                               WORLD_HALF_WIDTH};
-    std::uniform_real_distribution<float> posY{-WORLD_HALF_HEIGHT,
-                                               WORLD_HALF_HEIGHT};
-    std::uniform_real_distribution<float> angle{0.0f, glm::two_pi<float>()};
-
-    for (Boid& boid : boids) {
-      boid.position = {posX(rng), posY(rng)};
-      float theta = angle(rng);
-      boid.velocity = glm::vec2{std::cos(theta), std::sin(theta)} * MAX_SPEED;
-    }
-  }
-
-  void onUpdate(const sophia::FrameInfo& frameInfo) override {
-    float scrollDistance =
-        SCROLL_SPEED * static_cast<float>(frameInfo.deltaTime);
-    if (scrollLeft) camera.position.x -= scrollDistance;
-    if (scrollRight) camera.position.x += scrollDistance;
-    if (scrollUp) camera.position.y -= scrollDistance;
-    if (scrollDown) camera.position.y += scrollDistance;
-
-    updateBoids(static_cast<float>(frameInfo.deltaTime));
-
-    canvas.clear();
-    for (const Boid& boid : boids) {
-      drawBoid(boid);
-    }
-  }
-
- private:
-  void updateBoids(float deltaTime) {
-    std::vector<glm::vec2> accelerations(boids.size());
-
-    for (size_t i = 0; i < boids.size(); ++i) {
-      glm::vec2 separation{0.0f};
-      glm::vec2 averageVelocity{0.0f};
-      glm::vec2 averagePosition{0.0f};
-      int neighborCount = 0;
-
-      for (size_t j = 0; j < boids.size(); ++j) {
-        if (i == j) continue;
-
-        glm::vec2 offset = boids[i].position - boids[j].position;
-        float dist = glm::length(offset);
-        if (dist >= PERCEPTION_RADIUS) continue;
-
-        averageVelocity += boids[j].velocity;
-        averagePosition += boids[j].position;
-        ++neighborCount;
-
-        if (dist > 0.0f && dist < SEPARATION_RADIUS) {
-          separation += offset / (dist * dist);
-        }
-      }
-
-      glm::vec2 acceleration =
-          steerTowards(boids[i], separation) * SEPARATION_WEIGHT;
-
-      if (neighborCount > 0) {
-        averageVelocity /= static_cast<float>(neighborCount);
-        acceleration +=
-            steerTowards(boids[i], averageVelocity) * ALIGNMENT_WEIGHT;
-
-        averagePosition /= static_cast<float>(neighborCount);
-        glm::vec2 towardsGroup = averagePosition - boids[i].position;
-        acceleration += steerTowards(boids[i], towardsGroup) * COHESION_WEIGHT;
-      }
-
-      accelerations[i] = acceleration;
-    }
-
-    for (size_t i = 0; i < boids.size(); ++i) {
-      Boid& boid = boids[i];
-      boid.velocity += accelerations[i] * deltaTime;
-
-      float speed = glm::length(boid.velocity);
-      if (speed > MAX_SPEED) {
-        boid.velocity = boid.velocity / speed * MAX_SPEED;
-      }
-
-      boid.position += boid.velocity * deltaTime;
-      wrapPosition(boid.position);
-    }
-  }
-
-  // Steers boid towards desiredDirection at up to MAX_SPEED, clamped to
-  // MAX_FORCE.
-  glm::vec2 steerTowards(const Boid& boid, glm::vec2 desiredDirection) {
-    float directionLength = glm::length(desiredDirection);
-    if (directionLength < 1e-5f) return glm::vec2{0.0f};
-
-    glm::vec2 desired = desiredDirection / directionLength * MAX_SPEED;
-    glm::vec2 steer = desired - boid.velocity;
-
-    float steerLength = glm::length(steer);
-    if (steerLength > MAX_FORCE) {
-      steer = steer / steerLength * MAX_FORCE;
-    }
-    return steer;
-  }
-
-  void wrapPosition(glm::vec2& position) {
-    if (position.x > WORLD_HALF_WIDTH) position.x = -WORLD_HALF_WIDTH;
-    if (position.x < -WORLD_HALF_WIDTH) position.x = WORLD_HALF_WIDTH;
-    if (position.y > WORLD_HALF_HEIGHT) position.y = -WORLD_HALF_HEIGHT;
-    if (position.y < -WORLD_HALF_HEIGHT) position.y = WORLD_HALF_HEIGHT;
-  }
-
-  void drawBoid(const Boid& boid) {
-    constexpr float LENGTH = 20.0f;
-    constexpr float WIDTH = 12.0f;
-
-    glm::vec2 direction = boid.velocity;
-    float speed = glm::length(direction);
-    direction = speed > 1e-5f ? direction / speed : glm::vec2{0.0f, -1.0f};
-    glm::vec2 perpendicular{-direction.y, direction.x};
-
-    glm::vec2 nose = boid.position + direction * (LENGTH * 0.5f);
-    glm::vec2 tailLeft = boid.position - direction * (LENGTH * 0.5f) +
-                         perpendicular * (WIDTH * 0.5f);
-    glm::vec2 tailRight = boid.position - direction * (LENGTH * 0.5f) -
-                          perpendicular * (WIDTH * 0.5f);
-
-    canvas.triangle(nose, tailLeft, tailRight, {1.0f, 1.0f, 1.0f});
-  }
-
-  void setScrollKeyHeld(sophia::KeyCode keycode, bool held) {
-    if (keycode == sophia::Key::Left) scrollLeft = held;
-    if (keycode == sophia::Key::Right) scrollRight = held;
-    if (keycode == sophia::Key::Up) scrollUp = held;
-    if (keycode == sophia::Key::Down) scrollDown = held;
-  }
-
-  std::vector<Boid> boids;
-  bool scrollLeft = false;
-  bool scrollRight = false;
-  bool scrollUp = false;
-  bool scrollDown = false;
+  void onUpdate(const sophia::FrameInfo& frameInfo) override {}
 };

 SOPHIA_MAIN(Testbed)