Movement.

src/dusk/assert/assert.c

@@ -80,4 +80,45 @@ void assertDeprecatedImpl(
   const char *message
 ) {
   assertUnreachableImpl(file, line, message);
+}
+
+void assertMemoryRangeMatchesImpl(
+  const char *file,
+  const int32_t line,
+  const void *start,
+  const void *end,
+  const size_t size,
+  const char *message
+) {
+  assertTrueImpl(
+    file,
+    line,
+    start != NULL,
+    "Start pointer is NULL"
+  );
+  assertTrueImpl(
+    file,
+    line,
+    end != NULL,
+    "End pointer is NULL"
+  );
+  assertTrueImpl(
+    file,
+    line,
+    size > 0,
+    "Size is 0"
+  );
+  assertTrueImpl(
+    file,
+    line,
+    start < end,
+    "Start pointer is not before end pointer"
+  );
+
+  assertTrueImpl(
+    file,
+    line,
+    ((uintptr_t)end - (uintptr_t)start) == size,
+    message
+  );
 }

src/dusk/assert/assert.h

@@ -95,6 +95,15 @@ void assertDeprecatedImpl(
   const char *message
 );
 
+void assertMemoryRangeMatchesImpl(
+  const char *file,
+  const int32_t line,
+  const void *start,
+  const void *end,
+  const size_t size,
+  const char *message
+);
+
 #define assertTrue(x, message) \
   assertTrueImpl(__FILE__, __LINE__, x, message)
 
@@ -119,4 +128,5 @@ void assertDeprecatedImpl(
 #define assertStrLenMin(str, len, message) \
   assertTrue(strlen(str) >= len, message)
 
-// EOF
+#define assertMemoryRangeMatches(start, end, size, message) \
+  assertMemoryRangeMatchesImpl(__FILE__, __LINE__, start, end, size, message)

src/dusk/overworld/entity.c

@@ -7,6 +7,7 @@
 
 #include "entity.h"
 #include "assert/assert.h"
+#include "overworlddefs.h"
 
 entitycallback_t ENTITY_CALLBACKS[ENTITY_TYPE_COUNT] = {
   { NULL, NULL },
@@ -37,4 +38,59 @@ void entityUpdate(entity_t *ent) {
 
   assertNotNull(ENTITY_CALLBACKS[ent->type].update, "Entity type update err.");
   ENTITY_CALLBACKS[ent->type].update(ent);
+
+  // Handle moving
+  if(ent->subX > 0) {
+    ent->subX -= ENTITY_MOVE_SPEED;
+    if(ent->subX < 0) ent->subX = 0;
+  } else if(ent->subX < 0) {
+    ent->subX += ENTITY_MOVE_SPEED;
+    if(ent->subX > 0) ent->subX = 0;
+  } else if(ent->subY > 0) {
+    ent->subY -= ENTITY_MOVE_SPEED;
+    if(ent->subY < 0) ent->subY = 0;
+  } else if(ent->subY < 0) {
+    ent->subY += ENTITY_MOVE_SPEED;
+    if(ent->subY > 0) ent->subY = 0;
+  }
+}
+
+void entityTurn(entity_t *ent, const facingdir_t dir) {
+  assertNotNull(ent, "Entity cannot be NULL");
+  assertTrue(dir < FACING_DIRECTION_COUNT, "Invalid facing direction");
+
+  ent->direction = dir;
+}
+
+void entityMove(entity_t *ent, const facingdir_t dir) {
+  assertNotNull(ent, "Entity cannot be NULL");
+
+  entityTurn(ent, dir);
+
+  // Move
+  switch(dir) {
+    case FACING_DIRECTION_EAST:
+      ent->x++;
+      ent->subX = -OVERWORLD_ENTITY_WIDTH;
+      break;
+    case FACING_DIRECTION_WEST:
+      ent->x--;
+      ent->subX = OVERWORLD_ENTITY_WIDTH;
+      break;
+    case FACING_DIRECTION_NORTH:
+      ent->y++;
+      ent->subY = -OVERWORLD_ENTITY_HEIGHT;
+      break;
+    case FACING_DIRECTION_SOUTH:
+      ent->y--;
+      ent->subY = OVERWORLD_ENTITY_HEIGHT;
+      break;
+    default:
+      assertUnreachable("Invalid facing direction");
+  }
+}
+
+bool entityIsMoving(const entity_t *ent) {
+  assertNotNull(ent, "Entity cannot be NULL");
+  return ent->subX != 0 || ent->subY != 0;
 }

src/dusk/overworld/entity.h

@@ -26,10 +26,11 @@ typedef enum {
   FACING_DIRECTION_NORTH,
   FACING_DIRECTION_WEST
 } facingdir_t;
+#define FACING_DIRECTION_COUNT 4
 
 typedef struct _entity_t {
   uint8_t x, y;
-  uint8_t subX, subY;
+  int8_t subX, subY;
   facingdir_t direction;
   entitytype_t type;
 
@@ -38,6 +39,8 @@ typedef struct _entity_t {
   };
 } entity_t;
 
+#define ENTITY_MOVE_SPEED 4
+
 /**
  * Initializes an entity.
  * 
@@ -54,4 +57,28 @@ void entityInit(
  * 
  * @param entity The entity to update.
  */
-void entityUpdate(entity_t *entity);
+void entityUpdate(entity_t *entity);
+
+/**
+ * Turns an entity in a given direction.
+ * 
+ * @param entity The entity to turn.
+ * @param dir The direction to turn the entity.
+ */
+void entityTurn(entity_t *entity, const facingdir_t dir);
+
+/**
+ * Moves an entity in a given direction.
+ * 
+ * @param entity The entity to move.
+ * @param dir The direction to move the entity.
+ */
+void entityMove(entity_t *entity, const facingdir_t dir);
+
+/**
+ * Checks if an entity is moving.
+ * 
+ * @param entity The entity to check.
+ * @return TRUE if the entity is moving, FALSE otherwise.
+ */
+bool_t entityIsMoving(const entity_t *entity);

src/dusk/overworld/player.c

@@ -19,12 +19,12 @@ void playerUpdate(entity_t *ent) {
   assertNotNull(ent, "Entity cannot be NULL");
 
   if(inputWasPressed(INPUT_RIGHT)) {
-    ent->x++;
+    entityMove(ent, FACING_DIRECTION_EAST);
   } else if(inputWasPressed(INPUT_LEFT)) {
-    ent->x--;
+    entityMove(ent, FACING_DIRECTION_WEST);
   } else if(inputWasPressed(INPUT_UP)) {
-    ent->y--;
+    entityMove(ent, FACING_DIRECTION_NORTH);
   } else if(inputWasPressed(INPUT_DOWN)) {
-    ent->y++;
+    entityMove(ent, FACING_DIRECTION_SOUTH);
   }
 }

src/duskgl/display/shader/data/entities.c

@@ -27,8 +27,10 @@ void entitiesUpdate() {
     entitiesdataent_t *dst = &ENTITIES_DATA.entities[i];
 
     // Copy position data.
-    assertTrue(
+    assertMemoryRangeMatches(
-      (&src->subY - &src->x) + sizeof(uint8_t) == sizeof(uint_t),
+      &src->x,
+      &src->direction,
+      sizeof(uint_t),
       "Entity data is not packed correctly any more."
     );
     memcpy(&dst->position, &src->x, sizeof(uint_t));

src/duskgl/display/shader/data/entities.glsl

@@ -26,8 +26,8 @@ vec2 entityGetVertice(uint instanceIndex, uint indiceIndex) {
 
   uint x = packedGetU8(0u, entities[instanceIndex].position);
   uint y = packedGetU8(1u, entities[instanceIndex].position);
-  uint subX = packedGetU8(2u, entities[instanceIndex].position);
+  int subX = packedGetI8(2u, entities[instanceIndex].position);
-  uint subY = packedGetU8(3u, entities[instanceIndex].position);
+  int subY = packedGetI8(3u, entities[instanceIndex].position);
 
   vert.x += float(x);
   vert.y += float(y);

src/duskgl/display/shader/fragments/packed.glsl

@@ -5,4 +5,9 @@
 
 uint packedGetU8(uint position, uint data) {
   return (data >> (position * 8u)) & 0xFFu;
+}
+
+int packedGetI8(uint position, uint data) {
+  int shift = int(position * 8u);
+  return int(data << (24 - shift)) >> 24;
 }