A trigger area that turns the player red when he enters.

Author: BSVino

game/character.cpp

@@ -28,6 +28,7 @@ CCharacter::CCharacter()
 	m_bEnemyAI = false;
 	m_flRotationTheta = 0;
 	m_vecRotationAxis = Vector(0, 1, 0);
+	m_vecScaling = Vector(1, 1, 1);
 	m_bTakesDamage = false;
 	m_bDrawTransparent = false;
 	m_iHealth = 3;
@@ -216,3 +217,8 @@ const Vector CCharacter::GetGlobalView() const
 
 	return m_angView.ToVector();
 }
+
+const AABB CCharacter::GetGlobalAABB() const
+{
+	return m_aabbSize * m_vecScaling + GetGlobalOrigin();
+}

game/character.h

@@ -57,6 +57,8 @@ class CCharacter
 	void         SetLocalView(const EAngle& angView);
 	const Vector GetGlobalView() const;
 
+	const AABB   GetGlobalAABB() const;
+
 private:
 	void BuildTransform();
 

game/game.cpp

@@ -299,6 +299,11 @@ void CGame::Update(float dt)
 
 		pCharacter->SetTranslation(pCharacter->GetGlobalOrigin() + pCharacter->m_vecVelocity * dt);
 	}
+
+	if (AABBIntersection(m_hTrigger->GetGlobalAABB(), m_hPlayer->GetGlobalAABB()))
+		m_hPlayer->m_clrRender = Color(1.0f, 0.2f, 0.1f, 1.0f);
+	else
+		m_hPlayer->m_clrRender = Color(0.4f, 0.2f, 0.8f, 1.0f);
 }
 
 void CGame::Draw()
@@ -500,6 +505,12 @@ void CGame::DrawCharacters(const std::vector<CCharacter*>& apRenderList, bool bT
 			// http://youtu.be/7pe1xYzFCvA
 			c.Transform(pCharacter->GetGlobalTransform());
 
+			if (pCharacter->m_bDrawTransparent)
+			{
+				c.SetAlpha(0.6f);
+				c.SetBlend(BLEND_ALPHA);
+			}
+
 			// Render the player-box
 			c.RenderBox(pCharacter->m_aabbSize.vecMin, pCharacter->m_aabbSize.vecMax);
 		}
@@ -598,7 +609,7 @@ void CGame::GameLoop()
 	Vector vecMonsterMin = Vector(-1, 0, -1);
 	Vector vecMonsterMax = Vector(1, 2, 1);
 
-	CCharacter* pTarget1 = CreateCharacter();
+	/*CCharacter* pTarget1 = CreateCharacter();
 	pTarget1->SetTransform(Vector(2, 2, 2), 0, Vector(0, 1, 0), Vector(6, 0, 6));
 	pTarget1->m_aabbSize.vecMin = vecMonsterMin;
 	pTarget1->m_aabbSize.vecMax = vecMonsterMax;
@@ -620,7 +631,7 @@ void CGame::GameLoop()
 	pTarget3->m_aabbSize.vecMax = vecMonsterMax;
 	pTarget3->m_iBillboardTexture = m_iMonsterTexture;
 	pTarget3->m_bEnemyAI = true;
-	pTarget3->m_bTakesDamage = true;
+	pTarget3->m_bTakesDamage = true;*/
 
 	Vector vecPropMin = Vector(-1, 0, -1);
 	Vector vecPropMax = Vector(1, 2, 1);
@@ -649,6 +660,13 @@ void CGame::GameLoop()
 	pProp4->m_aabbSize.vecMax = vecPropMax;
 	pProp4->m_clrRender = Color(0.4f, 0.8f, 0.2f, 1.0f);
 
+	m_hTrigger = CreateCharacter();
+	m_hTrigger->SetTransform(Vector(10, 2, 4), 0, Vector(0, 1, 0), Vector(0, 0, -14));
+	m_hTrigger->m_aabbSize.vecMin = vecPropMin;
+	m_hTrigger->m_aabbSize.vecMax = vecPropMax;
+	m_hTrigger->m_bDrawTransparent = true;
+	m_hTrigger->m_clrRender = Color(0.8f, 0.4f, 0.2f, 0.5f);
+
 	float flPreviousTime = 0;
 	float flCurrentTime = Application()->GetTime();
 

game/game.h

@@ -104,6 +104,7 @@ class CGame : public CApplication
 
 	// This is the player character
 	CHandle m_hPlayer;
+	CHandle m_hTrigger;
 };
 
 inline CGame* Game()

math/collision.cpp

@@ -84,6 +84,20 @@ bool LineAABBIntersection(const AABB& aabbBox, const Vector& v0, const Vector& v
 	return true;
 }
 
+// Find the intersection of two axis-aligned bounding boxes http://youtu.be/ENuk9HgeTiI
+bool AABBIntersection(const AABB& a, const AABB& b)
+{
+	for (int i = 0; i < 3; i++)
+	{
+		if (a.vecMin.v[i] > b.vecMax.v[i])
+			return false;
+		if (a.vecMax.v[i] < b.vecMin.v[i])
+			return false;
+	}
+
+	return true;
+}
+
 // Line-Plane Intersection: http://youtu.be/fIu_8b2n8ZM
 bool LinePlaneIntersection(const Vector& n, const Vector& c, const Vector& x0, const Vector& x1, Vector& vecIntersection, float& flFraction)
 {

math/collision.h

@@ -21,6 +21,7 @@ class Vector;
 class AABB;
 
 bool LineAABBIntersection(const AABB& aabbBox, const Vector& v0, const Vector& v1, Vector& vecIntersection, float& flFraction);
+bool AABBIntersection(const AABB& a, const AABB& b);
 
 // n - plane normal
 // c - any point in the plane