From 971fee4a0cfaa0b9017718a8a9e2ade928bc05f2 Mon Sep 17 00:00:00 2001
From: verysecrethero <hnorthh@gmail.com>
Date: Tue, 9 Feb 2016 15:38:21 +0100
Subject: [PATCH] DamageIndicatorSystem code looking good. Test working well.
 Sprite display fixed by Viktor

---
 include/Game/Systems/DamageIndicatorSystem.h  |  1 +
 .../Schema/Entities/SpriteTestTemporary.xml   |  7 +---
 resources/Shaders/Sprite.vert.glsl            |  2 +-
 src/Game/Systems/DamageIndicatorSystem.cpp    | 42 +++++++++++++++----
 4 files changed, 37 insertions(+), 15 deletions(-)

diff --git a/include/Game/Systems/DamageIndicatorSystem.h b/include/Game/Systems/DamageIndicatorSystem.h
index 646887e2..561654d1 100644
--- a/include/Game/Systems/DamageIndicatorSystem.h
+++ b/include/Game/Systems/DamageIndicatorSystem.h
@@ -16,6 +16,7 @@
 #include "Rendering/ESetCamera.h"
 
 #include <glm/gtc/quaternion.hpp>
+#include <glm/gtx/vector_angle.hpp>
 
 class DamageIndicatorSystem : public ImpureSystem
 {
diff --git a/resources/Schema/Entities/SpriteTestTemporary.xml b/resources/Schema/Entities/SpriteTestTemporary.xml
index f66e9158..2d02443c 100644
--- a/resources/Schema/Entities/SpriteTestTemporary.xml
+++ b/resources/Schema/Entities/SpriteTestTemporary.xml
@@ -3,13 +3,10 @@
 
   <Components>
     <c:Sprite>
-      <DiffuseTexture>Textures/DefenderGunRedDiff.png</DiffuseTexture>
-      <GlowMap>Textures/DefenderGunRedIncd.png</GlowMap>
+      <DiffuseTexture>Textures/TempDamageIndicator.png</DiffuseTexture>
+      <GlowMap>Textures/TempDamageIndicator.png</GlowMap>
       <Color A="1" B="0.721568644" G="1" R="0.839215696"/>
     </c:Sprite>
-    <c:Model>
-      <Resource>Models/Core/UnitQuad.mesh</Resource>
-    </c:Model>
     <c:Transform>
       <Position X="0" Y="0" Z="-0.472000033"/>
       <Scale X="0.100000001" Y="0.200000003" Z="0.5"/>
diff --git a/resources/Shaders/Sprite.vert.glsl b/resources/Shaders/Sprite.vert.glsl
index e910a26a..61b387ad 100644
--- a/resources/Shaders/Sprite.vert.glsl
+++ b/resources/Shaders/Sprite.vert.glsl
@@ -16,7 +16,7 @@ out VertexData{
 
 void main()
 {
-	gl_Position = P  * M * vec4(Position, 1.0);
+	gl_Position = P * V * M * vec4(Position, 1.0);
 
 	Output.Position = Position;
 	Output.TextureCoordinate = TextureCoords;
diff --git a/src/Game/Systems/DamageIndicatorSystem.cpp b/src/Game/Systems/DamageIndicatorSystem.cpp
index 5f6ad725..24d1cfa4 100644
--- a/src/Game/Systems/DamageIndicatorSystem.cpp
+++ b/src/Game/Systems/DamageIndicatorSystem.cpp
@@ -21,22 +21,46 @@ bool DamageIndicatorSystem::OnPlayerDamageTaken(Events::PlayerDamage& e)
 {
     auto test1 = (glm::vec3)e.PlayerShooter["Transform"]["Orientation"];
     auto test2 = (glm::vec3)e.Player["Transform"]["Orientation"];
-    //calculate direction
-    auto enemyOrientation = glm::quat(((glm::vec3)e.PlayerShooter["Transform"]["Orientation"]));
+
+    //grab players direction
     auto playerOrientation = glm::quat((glm::vec3)e.Player["Transform"]["Orientation"]);
-    //calculate difference in angle (quaternion math)
-    auto angle1 = glm::angle(playerOrientation);
-    auto angle2 = glm::angle(enemyOrientation);
-    auto quat = glm::angleAxis(angle2 - angle1, glm::vec3(0, 1, 0));
-    auto vec3Orientation = glm::eulerAngles(quat);
+
+    //get the position vectors, but ignore the y-height
+    auto enemyPosition = (glm::vec3) e.PlayerShooter["Transform"]["Position"];
+    auto playerPosition = (glm::vec3) e.Player["Transform"]["Position"];
+    enemyPosition.y = 0.0f;
+    playerPosition.y = 0.0f;
+
+    //calculate the enemy to player vector
+    auto enemyPlayerVector = glm::normalize((glm::vec3) playerPosition - enemyPosition);
+
+    //get angle from players current rotation, this angle is how much you rotate around the y-axis
+    auto playerAngle = glm::angle(playerOrientation);
+    auto playerRotationVector = glm::normalize(glm::rotateY(glm::vec3(0, 0, 1), playerAngle));
+
+    //dot product of players direction-vector and enemys-to-playervector will give the cos of the angle between the vectors
+    auto playerRotationDot = glm::dot(playerRotationVector, enemyPlayerVector);
+    //to get the angle between the vectors just do cos-inverse
+    auto angleBetweenVectors = glm::acos(playerRotationDot);
+
+    //rotate the direction-vector 90 degrees to get the players side-vector
+    auto playerSideVector = glm::normalize(glm::rotateY(glm::vec3(0, 0, 1), playerAngle + 1.57f));
+    //dot of sidevector positive = enemy is on the right side, dot sidevector negative = left side
+    auto playerSideVectorDot = glm::dot(playerSideVector, enemyPlayerVector);
+    if (playerSideVectorDot < 0) {
+        angleBetweenVectors = -angleBetweenVectors;
+    }
+
+    //LOG_INFO("vector angle %f %f %f %f", t1, t3, t4, enemyPlayerVector.x);
 
     //load & set the "2d" sprite
     auto entityFile = ResourceManager::Load<EntityFile>("Schema/Entities/SpriteTestTemporary.xml");
     EntityFileParser parser(entityFile);
     EntityID spriteID = parser.MergeEntities(m_World);
     m_World->SetParent(spriteID, m_CurrentCamera);
-    auto cameraWrapper = EntityWrapper(m_World, spriteID);
-    cameraWrapper["Transform"]["Orientation"] = vec3Orientation;
+    auto spriteWrapper = EntityWrapper(m_World, spriteID);
+    //simply set the rotation z-wise to the angleBetweenVectors
+    spriteWrapper["Transform"]["Orientation"] = glm::vec3(0, 0, angleBetweenVectors);
 
     return true;
 }