From b7063963b85598f1dc876fb328c1948fa90f6cb9 Mon Sep 17 00:00:00 2001
From: Doyle Thai <dyl.thai@gmail.com>
Date: Sat, 25 Jun 2016 19:12:25 +1000
Subject: [PATCH] Add basic AABB collision detection

---
 src/Renderer.c               |  6 ++---
 src/WorldTraveller.c         | 44 ++++++++++++++++++++++++++++++++----
 src/include/Dengine/Entity.h | 13 +++++++++++
 3 files changed, 55 insertions(+), 8 deletions(-)

diff --git a/src/Renderer.c b/src/Renderer.c
index b43baa4..a5fbf24 100644
--- a/src/Renderer.c
+++ b/src/Renderer.c
@@ -21,16 +21,14 @@ void renderer_entity(Renderer *renderer, Entity *entity, f32 rotate, v3 color)
 	// this->shader->uniformSetVec3f("spriteColor", color);
 
 	glActiveTexture(GL_TEXTURE0);
-	glCheckError();
 	glBindTexture(GL_TEXTURE_2D, entity->tex->id);
-	glCheckError();
 	shader_uniformSet1i(renderer->shader, "tex", 0);
 	glCheckError();
 
 	glBindVertexArray(renderer->vao);
-	glCheckError();
 	glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
-	glCheckError();
 	glBindVertexArray(0);
+
+	glBindTexture(GL_TEXTURE_2D, 0);
 	glCheckError();
 }
diff --git a/src/WorldTraveller.c b/src/WorldTraveller.c
index 1596afe..405517f 100644
--- a/src/WorldTraveller.c
+++ b/src/WorldTraveller.c
@@ -44,6 +44,7 @@ void worldTraveller_gameInit(GameState *state)
 	                  V2(58.0f, 98.0f),
 	                  direction_east,
 	                  asset_getTexture(texlist_hero),
+	                  TRUE,
 	                  0,
 	                  0,
 	                  0};
@@ -89,6 +90,7 @@ void worldTraveller_gameInit(GameState *state)
 	                 hero->size,
 	                 direction_null,
 	                 hero->tex,
+	                 TRUE,
 	                 0,
 	                 0,
 	                 0};
@@ -193,7 +195,8 @@ INTERNAL void parseInput(GameState *state, const f32 dt)
 			currAnim->currRectIndex = 0;
 			hero->currAnimIndex     = 0;
 		}
-	} else if (hero->currAnimIndex == 0)
+	}
+	else if (hero->currAnimIndex == 0)
 	{
 		SpriteAnim *currAnim    = &hero->anim[hero->currAnimIndex];
 		currAnim->currDuration  = currAnim->duration;
@@ -221,9 +224,42 @@ INTERNAL void parseInput(GameState *state, const f32 dt)
 	v2 dPos     = v2_scale(hero->dPos, dt);
 	v2 newHeroP = v2_add(v2_add(ddPosNew, dPos), hero->pos);
 
-	// f'(t) = curr velocity = a*t + v, where v is old velocity
-    hero->dPos = v2_add(hero->dPos, v2_scale(ddPos, dt));
-	hero->pos  = newHeroP;
+	b32 heroCollided = FALSE;
+	if (hero->collides == TRUE)
+	{
+		for (i32 i = 0; i < ARRAY_COUNT(state->entityList); i++)
+		{
+			if (i == state->heroIndex) continue;
+			Entity entity = state->entityList[i];
+			if (entity.collides)
+			{
+				v4 heroRect =
+				    V4(newHeroP.x, newHeroP.y, (newHeroP.x + hero->size.x),
+				       (newHeroP.y + hero->size.y));
+				v4 entityRect = getEntityScreenRect(entity);
+
+				if (((heroRect.z >= entityRect.x && heroRect.z <= entityRect.z) ||
+				     (heroRect.x >= entityRect.x && heroRect.x <= entityRect.z)) &&
+				    ((heroRect.w <= entityRect.y && heroRect.w >= entityRect.w) ||
+				     (heroRect.y <= entityRect.y && heroRect.y >= entityRect.w)))
+				{
+					heroCollided = TRUE;
+					break;
+				}
+			}
+		}
+	}
+
+	if (heroCollided)
+	{
+		hero->dPos = V2(0.0f, 0.0f);
+	}
+	else
+	{
+		// f'(t) = curr velocity = a*t + v, where v is old velocity
+		hero->dPos = v2_add(hero->dPos, v2_scale(ddPos, dt));
+		hero->pos  = newHeroP;
+	}
 }
 
 void worldTraveller_gameUpdateAndRender(GameState *state, const f32 dt)
diff --git a/src/include/Dengine/Entity.h b/src/include/Dengine/Entity.h
index 75aa878..0923d56 100644
--- a/src/include/Dengine/Entity.h
+++ b/src/include/Dengine/Entity.h
@@ -31,11 +31,24 @@ typedef struct Entity
 	v2 size;
 	enum Direction direction;
 	Texture *tex;
+	b32 collides;
 
 	// TODO(doyle): String based access
 	SpriteAnim anim[16];
 	i32 freeAnimIndex;
 	i32 currAnimIndex;
+
 } Entity;
 
+INTERNAL inline v4 getEntityScreenRect(Entity entity)
+{
+	v2 entityUpperLeftBound  = v2_add(entity.pos, V2(0.0f, entity.size.y));
+	v2 entityLowerRightBound = v2_add(entity.pos, V2(entity.size.x, 0.0f));
+
+	v4 result = V4(entityUpperLeftBound.x, entityUpperLeftBound.y,
+	               entityLowerRightBound.x, entityLowerRightBound.y);
+
+	return result;
+}
+
 #endif