Added target velocity HEAD master

The acceleration of a Ponderable entity is now only really a magnitude. The direction of acceleration is such that the velocity goes toward the target velocity. If accelerating would cause the velocity to pass the target velocity, it is instead set to the target.

This is currently being used to 1) generalize terminal velocity due to gravity, and 2) allow an Orientable entity to accelerate quickly to a walking speed (and to a halt) rather than instantly achieve it.

4 files changed, 61 insertions, 28 deletions

@@ -56,6 +56,11 @@ public:
   vec2d accel = { 0.0, 0.0 };
 
   /**
+   * The target velocity of the body.
+   */
+  vec2d targetVel = { 0.0, 0.0 };
+
+  /**
    * The type of physical body that the entity is meant to assume. The body will
    * be acted upon differently based on this. See the enumeration above for more
    * details.
@@ -20,30 +20,6 @@ void OrientingSystem::tick(double)
     auto& ponderable = game_.getEntityManager().
       getComponent<PonderableComponent>(entity);
 
-    switch (orientable.getWalkState())
-    {
-      case OrientableComponent::WalkState::still:
-      {
-        ponderable.vel.x() = 0.0;
-
-        break;
-      }
-
-      case OrientableComponent::WalkState::left:
-      {
-        ponderable.vel.x() = -WALK_SPEED;
-
-        break;
-      }
-
-      case OrientableComponent::WalkState::right:
-      {
-        ponderable.vel.x() = WALK_SPEED;
-
-        break;
-      }
-    }
-
     if (orientable.isJumping() && (ponderable.vel.y() > 0))
     {
       orientable.setJumping(false);
@@ -62,6 +38,8 @@ void OrientingSystem::moveLeft(id_type entity)
   orientable.setFacingRight(false);
   orientable.setWalkState(OrientableComponent::WalkState::left);
 
+  ponderable.targetVel.x() = -WALK_SPEED;
+
   auto& animating = game_.getSystemManager().getSystem<AnimatingSystem>();
   if (ponderable.grounded)
   {
@@ -82,6 +60,8 @@ void OrientingSystem::moveRight(id_type entity)
   orientable.setFacingRight(true);
   orientable.setWalkState(OrientableComponent::WalkState::right);
 
+  ponderable.targetVel.x() = WALK_SPEED;
+
   auto& animating = game_.getSystemManager().getSystem<AnimatingSystem>();
   if (ponderable.grounded)
   {
@@ -93,10 +73,14 @@ void OrientingSystem::moveRight(id_type entity)
 
 void OrientingSystem::stopWalking(id_type entity)
 {
+  auto& ponderable = game_.getEntityManager().
+    getComponent<PonderableComponent>(entity);
+
   auto& orientable = game_.getEntityManager().
     getComponent<OrientableComponent>(entity);
 
   orientable.setWalkState(OrientableComponent::WalkState::still);
+  ponderable.targetVel.x() = 0;
 
   auto& animating = game_.getSystemManager().getSystem<AnimatingSystem>();
 
@@ -5,6 +5,7 @@
 #include "components/playable.h"
 #include "components/controllable.h"
 #include "components/orientable.h"
+#include "components/ponderable.h"
 #include "systems/mapping.h"
 #include "systems/pondering.h"
 #include "systems/orienting.h"
@@ -46,6 +47,10 @@ void PlayingSystem::initPlayer()
     player,
     PonderableComponent::Type::freefalling);
 
+  auto& ponderable = game_.getEntityManager().
+    getComponent<PonderableComponent>(player);
+  ponderable.accel.x() = 720;
+
   game_.getEntityManager().emplaceComponent<ControllableComponent>(player);
   game_.getEntityManager().emplaceComponent<OrientableComponent>(player);
 
@@ -44,6 +44,7 @@ void PonderingSystem::initializeBody(
 
   if (type == PonderableComponent::Type::freefalling)
   {
+    ponderable.targetVel.y() = TERMINAL_VELOCITY;
     ponderable.accel.y() = NORMAL_GRAVITY;
   }
 }
@@ -57,6 +58,8 @@ void PonderingSystem::initPrototype(id_type prototype)
   ponderable.vel.y() = 0.0;
   ponderable.accel.x() = 0.0;
   ponderable.accel.y() = 0.0;
+  ponderable.targetVel.x() = 0.0;
+  ponderable.targetVel.y() = 0.0;
   ponderable.grounded = false;
   ponderable.frozen = false;
   ponderable.collidable = true;
@@ -98,12 +101,48 @@ void PonderingSystem::tickBody(
   // Accelerate
   if (!ponderable.frozen)
   {
-    ponderable.vel += ponderable.accel * dt;
+    // Determine the effective acceleration, which should be in the direction of
+    // the target velocity.
+    vec2d effAcc = ponderable.accel;
 
-    if ((ponderable.type == PonderableComponent::Type::freefalling)
-      && (ponderable.vel.y() > TERMINAL_VELOCITY))
+    if (ponderable.vel.x() == ponderable.targetVel.x())
     {
-      ponderable.vel.y() = TERMINAL_VELOCITY;
+      effAcc.x() = 0.0;
+    }
+    else if ((ponderable.accel.x() > 0 &&
+              ponderable.targetVel.x() < ponderable.vel.x()) ||
+             (ponderable.accel.x() < 0 &&
+              ponderable.targetVel.x() > ponderable.vel.x()))
+    {
+      effAcc.x() = -effAcc.x();
+    }
+
+    if (ponderable.vel.y() == ponderable.targetVel.y())
+    {
+      effAcc.y() = 0.0;
+    }
+    else if ((ponderable.accel.y() > 0 &&
+              ponderable.targetVel.y() < ponderable.vel.y()) ||
+             (ponderable.accel.y() < 0 &&
+              ponderable.targetVel.y() > ponderable.vel.y()))
+    {
+      effAcc.y() = -effAcc.y();
+    }
+
+    // Accelerate
+    ponderable.vel += effAcc * dt;
+
+    // If the velocity crossed the target velocity, set it to the target
+    if ((effAcc.x() > 0 && ponderable.vel.x() > ponderable.targetVel.x()) ||
+        (effAcc.x() < 0 && ponderable.vel.x() < ponderable.targetVel.x()))
+    {
+      ponderable.vel.x() = ponderable.targetVel.x();
+    }
+
+    if ((effAcc.y() > 0 && ponderable.vel.y() > ponderable.targetVel.y()) ||
+        (effAcc.y() < 0 && ponderable.vel.y() < ponderable.targetVel.y()))
+    {
+      ponderable.vel.y() = ponderable.targetVel.y();
     }
   }