From 3955e1d60c1d388b39599c5eaa3c343d064bac85 Mon Sep 17 00:00:00 2001
From: William Moberg <william.moberg@live.se>
Date: Fri, 22 Jan 2016 13:46:09 +0100
Subject: [PATCH] Can resolve collision when AABB corners cut through triangle.

At least two more cases left to resolve.
---
 .../Schema/Entities/ModelCollisionTest.xml    | 35 ++++++++++++++-----
 src/Engine/Collision/Collision.cpp            |  8 ++---
 src/Engine/Collision/CollisionSystem.cpp      |  8 ++++-
 3 files changed, 37 insertions(+), 14 deletions(-)

diff --git a/resources/Schema/Entities/ModelCollisionTest.xml b/resources/Schema/Entities/ModelCollisionTest.xml
index fd26f0c5..f7a547f5 100644
--- a/resources/Schema/Entities/ModelCollisionTest.xml
+++ b/resources/Schema/Entities/ModelCollisionTest.xml
@@ -2,7 +2,9 @@
 <Entity xmlns:c="components" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../Types/Entity.xsd">
 
   <Components>
-    <c:Transform/>
+    <c:Transform>
+      <Position X="0" Y="0" Z="-0.313012958"/>
+    </c:Transform>
   </Components>
 
   <Children>
@@ -11,8 +13,8 @@
         <c:Camera/>
         <c:Listener/>
         <c:Transform>
-          <Position X="5.01875639" Y="2.58534265" Z="3.01552486"/>
-          <Orientation X="-0.331608921" Y="1.01212442" Z="1.23717996e-06"/>
+          <Position X="2.56531811" Y="0.637967348" Z="0.202344239"/>
+          <Orientation X="2.68780756" Y="1.36143553" Z="3.14159179"/>
         </c:Transform>
       </Components>
       <Children/>
@@ -21,25 +23,40 @@
       <Components>
         <c:Collidable/>
         <c:Model>
-          <Resource>../assets/Models/Core/UnitCube.obj</Resource>
-          <Color A="1" B="0" G="0" R="1"/>
+          <Resource>../assets/Models/Core/UnitQuad.obj</Resource>
+          <Color A="1" B="1" G="0.392156869" R="0"/>
         </c:Model>
         <c:Transform>
-          <Scale X="0.200000003" Y="0.200000003" Z="0.200000003"/>
+          <Position X="-0.941270411" Y="-0.594426811" Z="2.90833044"/>
+          <Scale X="1.10000002" Y="1" Z="0.200000003"/>
+          <Orientation X="5.78700018" Y="2.59000015" Z="0"/>
         </c:Transform>
       </Components>
-      <Children/>
+      <Children>
+        <Entity>
+          <Components>
+            <c:Model>
+              <Resource>../assets/Models/Core/UnitQuad.obj</Resource>
+              <Color A="1" B="0" G="0" R="1"/>
+            </c:Model>
+            <c:Transform>
+              <Orientation X="0" Y="3.1415927" Z="4.71238898"/>
+            </c:Transform>
+          </Components>
+          <Children/>
+        </Entity>
+      </Children>
     </Entity>
     <Entity>
       <Components>
         <c:AABB/>
         <c:Collidable/>
-        <c:Physics/>
         <c:Model>
           <Resource>../assets/Models/Core/UnitCube.obj</Resource>
         </c:Model>
+        <c:Physics/>
         <c:Transform>
-          <Position X="1.96935618" Y="1.31790924" Z="-1.02448177"/>
+          <Position X="-0.30590561" Y="-0.251752943" Z="2.13862514"/>
         </c:Transform>
       </Components>
       <Children/>
diff --git a/src/Engine/Collision/Collision.cpp b/src/Engine/Collision/Collision.cpp
index d643e8cc..d174eb86 100644
--- a/src/Engine/Collision/Collision.cpp
+++ b/src/Engine/Collision/Collision.cpp
@@ -299,7 +299,7 @@ bool AABBvsTriangle(const AABB& box, const glm::vec3& v0, const glm::vec3& v1, c
     //closest to being perpendicular to the plane of the polygon.
 
     triNormal = glm::normalize(triNormal);
-    glm::vec3 diagonal = signNonZero(triNormal) * half;
+    glm::vec3 diagonal = -signNonZero(triNormal) * half;
 #define EARLY_OUT_OR_MAYBE_JUST_EXTRA_WORK
 #ifdef EARLY_OUT_OR_MAYBE_JUST_EXTRA_WORK
     //The triangle plane contains all points P in dot(triNormal, P) == dot(triNormal, v0)
@@ -323,9 +323,9 @@ bool AABBvsTriangle(const AABB& box, const glm::vec3& v0, const glm::vec3& v1, c
             return false;
         }
 #endif
-        float dist = glm::dot(triNormal, origin + diagonal - v0);
-        outResolutionVector = dist * triNormal;
-        LOG_DEBUG("Triangle collision corner");
+        //Distance between triangle plane, and the diagonal corner, multiplied by the normal.
+        //Signed distance, positive if on the same side as the normal.
+        outResolutionVector = -glm::dot(triNormal, origin + diagonal - v0) * triNormal;
         return true;
     }
     return false;
diff --git a/src/Engine/Collision/CollisionSystem.cpp b/src/Engine/Collision/CollisionSystem.cpp
index 657cc90b..11d2a836 100644
--- a/src/Engine/Collision/CollisionSystem.cpp
+++ b/src/Engine/Collision/CollisionSystem.cpp
@@ -51,7 +51,13 @@ void CollisionSystem::UpdateComponent(EntityWrapper& entity, ComponentWrapper& c
         auto absScale = Transform::AbsoluteScale(m_World, cModel.EntityID);
         glm::mat4 modelMatrix = glm::translate(absPosition) * glm::toMat4(absOrientation) * glm::scale(absScale);
 
-        RawModel* model = ResourceManager::Load<RawModel>(cModel["Resource"]);
+        RawModel* model;
+        try {
+            model = ResourceManager::Load<RawModel, true>(cModel["Resource"]);
+        } catch (const std::exception&) {
+            continue;
+        }
+
         glm::vec3 resolutionVector;
         if (Collision::AABBvsTriangles(boxA, model->m_Vertices, model->m_Indices, modelMatrix, resolutionVector)) {
             (glm::vec3&)cTransform["Position"] += resolutionVector;