From d7975eacb7c9b89c0fad37ec454388d20072f41b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dominik=20Madar=C3=A1sz?= <zaklaus@outlook.com>
Date: Sat, 8 May 2021 11:22:25 +0200
Subject: [PATCH] introduce HandleCollisions system

---
 code/modules/modules/physics.h    |  2 ++
 code/modules/source/controllers.c |  4 ++--
 code/modules/source/physics.c     | 12 +++++++++++-
 3 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/code/modules/modules/physics.h b/code/modules/modules/physics.h
index 21a0ee2..f41cc29 100644
--- a/code/modules/modules/physics.h
+++ b/code/modules/modules/physics.h
@@ -13,6 +13,7 @@ typedef struct {
     ECS_DECLARE_COMPONENT(Velocity);
     ECS_DECLARE_ENTITY(MoveWalk);
     ECS_DECLARE_ENTITY(UpdateTrackerPos);
+    ECS_DECLARE_ENTITY(HandleCollisions);
 } Physics;
 
 #define PhysicsImportHandles(handles)\
@@ -22,5 +23,6 @@ typedef struct {
     ECS_IMPORT_COMPONENT(handles, Velocity);\
     ECS_IMPORT_ENTITY(handles, MoveWalk);\
     ECS_IMPORT_ENTITY(handles, UpdateTrackerPos);\
+    ECS_IMPORT_ENTITY(handles, HandleCollisions);\
 
 void PhysicsImport(ecs_world_t *ecs);
diff --git a/code/modules/source/controllers.c b/code/modules/source/controllers.c
index 69bab8a..7890319 100644
--- a/code/modules/source/controllers.c
+++ b/code/modules/source/controllers.c
@@ -20,8 +20,8 @@ void MovementImpulse(ecs_iter_t *it) {
     }
 }
 
-#define DEMO_NPC_CHANGEDIR_FACTOR 0.03
-#define DEMO_NPC_MOVE_SPEED 100
+#define DEMO_NPC_CHANGEDIR_FACTOR 0.01
+#define DEMO_NPC_MOVE_SPEED 1000
 
 void DemoNPCMoveAround(ecs_iter_t *it) {
     Velocity *v = ecs_column(it, Velocity, 1);
diff --git a/code/modules/source/physics.c b/code/modules/source/physics.c
index d99a498..ce0c3e4 100644
--- a/code/modules/source/physics.c
+++ b/code/modules/source/physics.c
@@ -14,7 +14,14 @@ void MoveWalk(ecs_iter_t *it) {
         p[i].y += v[i].y * it->delta_time;
         v[i].x = zpl_lerp(v[i].x, 0.0f, PHY_WALK_DRAG);
         v[i].y = zpl_lerp(v[i].y, 0.0f, PHY_WALK_DRAG);
-        
+    }
+}
+
+void HandleCollisions(ecs_iter_t *it) {
+    Position *p = ecs_column(it, Position, 1);
+    Velocity *v = ecs_column(it, Velocity, 2);
+    
+    for (int i = 0; i < it->count; i++) {
         // NOTE(zaklaus): world bounds
         {
             double w = (double)world_dim()/2.0;
@@ -43,6 +50,7 @@ void PhysicsImport(ecs_world_t *ecs) {
     ECS_META(ecs, Velocity);
 
     ECS_SYSTEM(ecs, MoveWalk, EcsOnUpdate, general.Position, Velocity);
+    ECS_SYSTEM(ecs, HandleCollisions, EcsOnValidate, general.Position, Velocity);
     ECS_SYSTEM(ecs, UpdateTrackerPos, EcsPostUpdate, general.Position);
 
     ECS_SET_TYPE(Movement);
@@ -50,4 +58,6 @@ void PhysicsImport(ecs_world_t *ecs) {
     ECS_SET_ENTITY(Flying);
     ECS_SET_COMPONENT(Velocity);
     ECS_SET_ENTITY(MoveWalk);
+    ECS_SET_ENTITY(UpdateTrackerPos);
+    ECS_SET_ENTITY(HandleCollisions);
 }