Add player camera controller

game/src/scene/camera_controller.cpp

@@ -0,0 +1,72 @@
+#include "camera_controller.h"
+
+#include <algorithm>
+#include <cmath>
+
+namespace ns_game {
+
+namespace {
+
+float clampValue(float value, float minValue, float maxValue) {
+  if (maxValue < minValue) {
+    return minValue;
+  }
+  return std::clamp(value, minValue, maxValue);
+}
+
+float smoothFactor(float smoothing, float deltaTime) {
+  if (smoothing <= 0.0f) {
+    return 1.0f;
+  }
+  return 1.0f - std::exp(-smoothing * std::max(deltaTime, 0.0f));
+}
+
+} // namespace
+
+void CameraController::Configure(const CameraControllerConfig& config) {
+  config_ = config;
+}
+
+void CameraController::SnapToTarget(frostbite2D::Camera& camera,
+                                    const frostbite2D::Rect& targetBounds) {
+  camera.setPosition(clampToWorld(
+      resolveDesiredPosition(camera.getPosition(), targetBounds)));
+}
+
+void CameraController::Update(frostbite2D::Camera& camera,
+                              const frostbite2D::Rect& targetBounds,
+                              float deltaTime) {
+  const frostbite2D::Vec2 current = camera.getPosition();
+  const frostbite2D::Vec2 desired =
+      clampToWorld(resolveDesiredPosition(current, targetBounds));
+  const float t = smoothFactor(config_.smoothing, deltaTime);
+  camera.setPosition(frostbite2D::Vec2(
+      current.x + (desired.x - current.x) * t,
+      current.y + (desired.y - current.y) * t));
+}
+
+frostbite2D::Vec2 CameraController::resolveDesiredPosition(
+    const frostbite2D::Vec2& currentPosition,
+    const frostbite2D::Rect& targetBounds) const {
+  frostbite2D::Vec2 desired = currentPosition;
+  const float targetCenterX = targetBounds.left() + targetBounds.width() * 0.5f;
+  const float screenX = targetCenterX - currentPosition.x;
+  if (screenX < config_.deadZone.left()) {
+    desired.x = targetCenterX - config_.deadZone.left();
+  } else if (screenX > config_.deadZone.right()) {
+    desired.x = targetCenterX - config_.deadZone.right();
+  }
+  desired.y = config_.worldBounds.top();
+  return desired;
+}
+
+frostbite2D::Vec2 CameraController::clampToWorld(
+    const frostbite2D::Vec2& position) const {
+  return frostbite2D::Vec2(
+      clampValue(position.x, config_.worldBounds.left(),
+                 config_.worldBounds.right() - config_.viewportWidth),
+      clampValue(position.y, config_.worldBounds.top(),
+                 config_.worldBounds.bottom() - config_.viewportHeight));
+}
+
+} // namespace ns_game