From 04bbee09dd28feba713022d5aa0e0b3df3bebaa5 Mon Sep 17 00:00:00 2001
From: Emil Kosz <ekosz@int.pl>
Date: Wed, 4 Jun 2025 17:41:39 +0200
Subject: [PATCH] Bilinear interpolation for movement.

---
 game/src/chunk/manager.c  | 52 +++++++++++++++++++++++++++++++++------
 game/src/entity/manager.c |  8 +++++-
 game/src/entity/meshes.c  |  5 +++-
 game/src/event/handlers.c |  2 +-
 game/src/util.h           |  4 ---
 5 files changed, 57 insertions(+), 14 deletions(-)

diff --git a/game/src/chunk/manager.c b/game/src/chunk/manager.c
index 09c3093..2486c20 100644
--- a/game/src/chunk/manager.c
+++ b/game/src/chunk/manager.c
@@ -37,23 +37,61 @@ chunkman_world_to_chunk (float x, float z, int *cx, int *cz)
   *cz = floor (z / (float) CHUNK_DIM);
 }
 
+static inline float
+c_get_height (Chunk *c, int x, int z)
+{
+  return c ? c->heightmap[INDEX (x, z)] : 0.0;
+}
+
 float
 chunkman_get_height_at (float x, float z)
 {
   int cx, cz;
   chunkman_world_to_chunk (x, z, &cx, &cz);
   Chunk *chunk = chunkman_get_Chunk_at (cx, cz);
-  x -= cx * CHUNK_DIM;
-  z -= cz * CHUNK_DIM;
 
-  /* TODO: switch from this primitive system to something better. */
-  
-  if (chunk != NULL)
+  if (chunk == NULL)
     {
-      return chunk->heightmap[INDEX ((int) floor (x), (int) floor (z))];
+      return 0.0;
     }
+  
+  // Pozycja lokalna w chunku
+  float lx = x - cx * CHUNK_DIM;
+  float lz = z - cz * CHUNK_DIM;
 
-  return 0.0;
+  int x0 = (int) floor (lx);
+  int z0 = (int) floor (lz);
+  int x1 = x0 + 1;
+  int z1 = z0 + 1;
+
+  float tx = lx - x0;
+  float tz = lz - z0;
+
+  Chunk *r = NULL, *d = NULL, *c = NULL;
+  chunkman_get_Chunk_neighbors_at (cx, cz, &r, &d, &c);
+
+  float h00 = c_get_height (chunk, x0, z0);
+  float h10 = (x1 < CHUNK_DIM) ? c_get_height (chunk, x1, z0) :
+    (r ? c_get_height (r, 0, z0) : h00);
+  float h01 = (z1 < CHUNK_DIM) ? c_get_height (chunk, x0, z1) :
+    (d ? c_get_height (d, x0, 0) : h00);
+  float h11;
+
+  if (x1 < CHUNK_DIM && z1 < CHUNK_DIM)
+    h11 = c_get_height (chunk, x1, z1);
+  else if (x1 >= CHUNK_DIM && z1 < CHUNK_DIM)
+    h11 = r ? c_get_height (r, 0, z1) : h10;
+  else if (x1 < CHUNK_DIM && z1 >= CHUNK_DIM)
+    h11 = d ? c_get_height (d, x1, 0) : h01;
+  else
+    h11 = c ? c_get_height (c, 0, 0) : h00;
+
+  // Interpolacja
+  float h0 = h00 * (1 - tx) + h10 * tx;
+  float h1 = h01 * (1 - tx) + h11 * tx;
+  float height = h0 * (1 - tz) + h1 * tz;
+
+  return height;
 }
 
 void
diff --git a/game/src/entity/manager.c b/game/src/entity/manager.c
index fef847d..014a53a 100644
--- a/game/src/entity/manager.c
+++ b/game/src/entity/manager.c
@@ -8,6 +8,8 @@ static GSequence *entities;
 static EntityMesh mesh_quad2, mesh_quad_x;
 static unsigned int last_type = -1;
 
+#define CULL_FRUSTUM 0
+
 void
 character_on_tick (Entity *entity)
 {
@@ -70,6 +72,8 @@ entman_render_internal (gpointer data, gpointer userdata)
 
   /* TODO: Fix this up. It still isn't perfect, when you look up,
      sometimes the entities get culled. */
+
+  #if CULL_FRUSTUM
   
   vec4 planes[6];
   mat4 proj, view_proj;
@@ -91,6 +95,8 @@ entman_render_internal (gpointer data, gpointer userdata)
     {
       return;
     }
+
+  #endif
   
   EntityMesh to_render;
   
@@ -139,7 +145,7 @@ entman_render_internal (gpointer data, gpointer userdata)
       glm_translate (model, entity->position);
       break;
     default:
-      glm_rotate_at (model, entity->position, DEGTORAD (entity->rotation), (vec3) { 0.0, 1.0, 0.0 });
+      glm_rotate_at (model, entity->position, glm_rad (entity->rotation), (vec3) { 0.0, 1.0, 0.0 });
       glm_translate (model, entity->position);
       break;
     }
diff --git a/game/src/entity/meshes.c b/game/src/entity/meshes.c
index 63c6527..67a9f39 100644
--- a/game/src/entity/meshes.c
+++ b/game/src/entity/meshes.c
@@ -1,6 +1,9 @@
 #include "meshes.h"
 
-/* TODO: Split binding/rendering */
+/* TODO: Theoretically, we could fit all the transforms into one
+   vec4. The caveat? It would be for every vertex. There seems to be a
+   OpenGL function, glVertexAttrib, that repeats the attribute for
+   every subsequent vertex. */
 
 void
 EntityMesh_bind (EntityMesh *mesh)
diff --git a/game/src/event/handlers.c b/game/src/event/handlers.c
index 6cdb664..6cd80db 100644
--- a/game/src/event/handlers.c
+++ b/game/src/event/handlers.c
@@ -18,7 +18,7 @@ evt_handler_lookaround (SDL_Event *event)
       camera_rotation[0] -= event->motion.xrel / 100.f;
       camera_rotation[1] -= event->motion.yrel / 100.f;
       camera_rotation[1] =
-	CLAMP (camera_rotation[1], -M_PI / 2 + 0.025, M_PI / 2 - 0.025);
+	glm_clamp (camera_rotation[1], -M_PI / 2 + 0.025, M_PI / 2 - 0.025);
     }
 }
 
diff --git a/game/src/util.h b/game/src/util.h
index ecc1581..333e0f6 100644
--- a/game/src/util.h
+++ b/game/src/util.h
@@ -15,10 +15,6 @@
 #define WARN(fmt, args...)  (fprintf (stderr, COLOR_YELLOW "[W] %s:%d:%s(): " COLOR_RESET fmt "\n", __FILE__, __LINE__, __func__, ##args))
 #define FATAL(fmt, args...) (fprintf (stderr, COLOR_RED "[!] %s:%d:%s(): " COLOR_RESET fmt "\n", __FILE__, __LINE__, __func__, ##args), exit (-1))
 
-#define CLAMP(x, low, high) (((x) > (high)) ? (high) : (((x) < (low)) ? (low) : (x)))
-
-#define DEGTORAD(deg) ((deg) * (M_PI / 180.0))
-
 #define UNUSED(...)                   (UNUSED_1 (__VA_ARGS__, 0))
 #define UNUSED_1(arg, ...) (void) arg, UNUSED_2 (__VA_ARGS__, 0)
 #define UNUSED_2(arg, ...) (void) arg, UNUSED_3 (__VA_ARGS__, 0)