collide and move

3 files changed, 52 insertions, 2 deletions

diff --git a/src/entity.c b/src/entity.c
new file mode 100644
index 0000000..da7662e
--- /dev/null
+++ b/src/entity.c
@@ -0,0 +1,44 @@
+#include "entity.h"
+#include "game.h"
+#include "cfg.h"
+
+bool
+entity_collide(Entity *this, Game *g, int ox, int oy)
+{
+	(void)g;
+	const int x0 = this->pos[0] - this->width / 2 + ox;
+	const int y0 = this->pos[1] - this->height / 2 + oy;
+	const int x1 = x0 + this->width - 1;
+	const int y1 = y0 + this->height - 1;
+	return (x0 < 0 || y0 < 0 || x1 >= DISPLAY_WIDTH || y1 >= DISPLAY_HEIGHT);
+}
+
+void
+entity_move(Entity *this, Game *g)
+{
+	if (entity_collide(this, g, 0, 0)) {
+		this->vel[0] = 0.0;
+		this->vel[1] = 0.0;
+		this->rem[0] = 0.0;
+		this->rem[1] = 0.0;
+		return;
+	}
+	for (int a = 0; a < 2; a++) {
+		const double sum = this->vel[a] + this->rem[a];
+		int spd = (int)sum;
+		this->rem[a] = sum - spd;
+		const int sign = (spd > 0) - (spd < 0);
+		if (sign == 0)
+			continue;
+		while (spd != 0) {
+			this->pos[a] += sign;
+			if (entity_collide(this, g, 0, 0)) {
+				this->pos[a] -= sign;
+				this->rem[a] = 0.0;
+				this->vel[a] = 0.0;
+				break;
+			}
+			spd -= sign;
+		}
+	}
+}
diff --git a/src/entity.h b/src/entity.h
index 9f5861c..a1594e7 100644
--- a/src/entity.h
+++ b/src/entity.h
@@ -26,3 +26,6 @@ struct Entity {
 		Player player;
 	};
 };
+
+bool entity_collide(Entity *this, struct Game *g, int ox, int oy);
+void entity_move(Entity *this, struct Game *g);
diff --git a/src/player.c b/src/player.c
index 49dddde..9778746 100644
--- a/src/player.c
+++ b/src/player.c
@@ -7,8 +7,9 @@
 static void
 player_update(Entity *this, Game *g)
 {
-	(void)g;
-	this->pos[1] = this->pos[0] += 1;
+	this->vel[0] = 1.2;
+	this->vel[1] += 0.1;
+	entity_move(this, g);
 }
 
 static void
@@ -25,6 +26,8 @@ void
 player_init(Entity *this)
 {
 	memset(this, 0, sizeof(*this));
+	this->pos[0] = 16;
+	this->pos[1] = 16;
 	this->type = ET_PLAYER;
 	this->update = player_update;
 	this->draw = player_draw;