Base implementation of raycasting engine

1 files changed, 209 insertions, 0 deletions

diff --git a/src/main.c b/src/main.c
index cb652fd..6e0b7d0 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,9 +1,159 @@
 #include <GLFW/glfw3.h>
 #include <stdio.h>
+#include <math.h>
+
+// TODO: move to implicit map definition with level editor in future
+#define MAP_HEIGHT 10
+#define MAP_WIDTH 10
+int world_map[MAP_HEIGHT][MAP_WIDTH] = {
+    {1, 1, 1, 1, 1, 1, 1, 1, 1, 1},
+    {1, 0, 0, 0, 0, 0, 0, 0, 0, 1},
+    {1, 0, 0, 0, 0, 0, 2, 2, 0, 1},
+    {1, 0, 0, 0, 0, 0, 2, 2, 0, 1},
+    {1, 0, 0, 0, 0, 0, 0, 0, 0, 1},
+    {1, 0, 0, 0, 0, 0, 0, 0, 0, 1},
+    {1, 0, 3, 3, 0, 0, 4, 4, 0, 1},
+    {1, 0, 3, 3, 0, 0, 4, 4, 0, 1},
+    {1, 0, 0, 0, 0, 0, 0, 0, 0, 1},
+    {1, 1, 1, 1, 1, 1, 1, 1, 1, 1}
+};
+
+// TODO: move player code to dedicated file after complication demands it
+// TODO: implement y-shearing to allow players to look vertically
+typedef struct {
+	float pos_x, pos_y;
+	float dir_x, dir_y;
+	float plane_x, plane_y;
+	float move_speed;
+	float rot_speed;
+} Player;
+
+typedef struct {
+	unsigned char r, g, b;
+} ColorRGB;
+
+// honest- this function can from chatgpt- cross-reference this with other raycasting guides
+void raycast(Player *player) {
+    	int screen_width = 800;
+    	int screen_height = 600;
+
+    	for (int x = 0; x < screen_width; ++x) {
+        	// Calculate ray position and direction
+        	double camera_x = 2.0 * x / (double)screen_width - 1; // x-coordinate in camera space
+        	double ray_dir_x = player->dir_x + player->plane_x * camera_x;
+        	double ray_dir_y = player->dir_y + player->plane_y * camera_x;
+
+        	// Which box of the map we're in
+        	int map_x = (int)player->pos_x;
+        	int map_y = (int)player->pos_y;
+
+        	// Length of ray from one x or y-side to next x or y-side
+        	double delta_dist_x = fabs(1 / ray_dir_x);
+        	double delta_dist_y = fabs(1 / ray_dir_y);
+
+        	// Length of ray from current position to next x or y-side
+        	double side_dist_x;
+        	double side_dist_y;
+
+        	// Direction to step in x or y-direction (either +1 or -1)
+        	int step_x;
+        	int step_y;
+
+        	// Was a wall hit?
+        	int hit = 0;
+        	// Was the wall hit a wall facing north, east-west, or south?
+        	int side;
+        	if (ray_dir_x < 0) {
+            		step_x = -1;
+            		side_dist_x = (player->pos_x - map_x) * delta_dist_x;
+        	} else {
+            		step_x = 1;
+            		side_dist_x = (map_x + 1.0 - player->pos_x) * delta_dist_x;
+        	}
+        	if (ray_dir_y < 0) {
+            		step_y = -1;
+            		side_dist_y = (player->pos_y - map_y) * delta_dist_y;
+        	} else {
+            		step_y = 1;
+            		side_dist_y = (map_y + 1.0 - player->pos_y) * delta_dist_y;
+        	}
+
+        	// Perform DDA
+        	while (hit == 0) {
+            		// Jump to next map square
+            		if (side_dist_x < side_dist_y) {
+                		side_dist_x += delta_dist_x;
+                		map_x += step_x;
+                		side = (ray_dir_x > 0) ? 0 : 2;
+            		} else {
+                		side_dist_y += delta_dist_y;
+                		map_y += step_y;
+                		side = 1;
+            		}
+            		// Check if ray has hit a wall
+            		if (world_map[map_x][map_y] > 0) { hit = 1; }
+        	}
+
+		// calculate distance projected on camera direction
+		double perp_wall_dist;
+		if (side == 0 || side == 2) { perp_wall_dist = (map_x - player->pos_x + (1 - step_x) / 2) / ray_dir_x; }
+		else           { perp_wall_dist = (map_y - player->pos_y + (1 - step_y) / 2) / ray_dir_y; }
+		
+		// calculate height of line on screen
+		int line_height = (int)(screen_height / perp_wall_dist);
+		int draw_start = -line_height / 2 + screen_height / 2;
+		if (draw_start < 0) { draw_start = 0; }
+		int draw_end = line_height / 2 + screen_height / 2;
+		if (draw_end >= screen_height)  { draw_end = screen_height - 1; }
+
+
+		// colors :)
+
+		// TODO: currently, this effects both inside and outside faces
+		// which creates some awkward coloring issues with the outer walls.
+		// this may not be an issue in the final release, depending how walls
+		// are handled, but worth noting now.
+		ColorRGB color;
+		if (world_map[map_x][map_y] == 1)	color = (ColorRGB){.r = 255, .g = 255, .b = 255};
+		else if (world_map[map_x][map_y] == 2)	color = (ColorRGB){.r = 255, .g = 0, .b = 0};
+		else if (world_map[map_x][map_y] == 3)	color = (ColorRGB){.r = 0, .g = 255, .b = 0};
+		else if (world_map[map_x][map_y] == 4)	color = (ColorRGB){.r = 0, .g = 0, .b = 255};
+		else					color = (ColorRGB){.r = 0, .g = 0, .b = 0};
+
+		if (side == 1) {
+			color.r /= 2;
+			color.g /= 2;
+			color.b /= 2;
+		} else if (side == 2) {
+			color.r /= 4;
+			color.g /= 4;
+			color.b /= 4;
+		}
+
+		// TODO: recommended to put this in its own function or something at some point,
+		// as it deals with library calls outside of this function's scope
+		glBegin(GL_LINES);
+		glColor3ub(color.r, color.g, color.b);
+		glVertex2i(x, draw_start);
+		glVertex2i(x, draw_end);
+		glEnd();
+    	}
+}
 
 int main(int argc, char *argv[]) {
 	GLFWwindow* window;
 
+	// init player
+	Player player;
+	player.pos_y = 2.0f;
+	player.pos_x = 2.0f;
+	player.dir_x = 1.0f; // facing right
+	player.dir_y = 0.0f; // facing right
+	player.plane_x = 0.0f; // FOV related
+	player.plane_y = 0.66f; // FOV related
+	player.move_speed = 0.05f;
+	player.rot_speed = 0.1f;
+
 	// initiate glfw library
 	if (!glfwInit()){
 		printf("Failed to initiate GLFW.\n");
@@ -21,14 +171,73 @@ int main(int argc, char *argv[]) {
 	// make window current
 	glfwMakeContextCurrent(window);
 
+	// setup orthographic projection camera
+	glMatrixMode(GL_PROJECTION);
+	glLoadIdentity();
+	glOrtho(0.0, 800, 600, 0.0, -1.0, 1.0);
+	glMatrixMode(GL_MODELVIEW);
+
+	// TODO: move timers into a header
+	double last_time = glfwGetTime();
+	int nb_frames = 0;
+	// TODO: render FPS with freetype or something as opposed to updating title
+	char title[200];
+
 	while (!glfwWindowShouldClose(window)) {
 
+		// timing section
+		double current_time = glfwGetTime();
+		nb_frames++;
+		if (current_time - last_time >= 1.0) {
+			sprintf(title, "FPS: %d", nb_frames);
+			glfwSetWindowTitle(window, title);
+			nb_frames = 0;
+			last_time += 1.0;
+		}
+
+		// clear window
 		glClear(GL_COLOR_BUFFER_BIT);
+		glLoadIdentity();
+
+		// main raycast function
+		raycast(&player);
+
+		// movement and camera rotation
+		// TODO: eventually translate movement from a header
+		if (glfwGetKey(window, GLFW_KEY_W) == GLFW_PRESS) {
+			player.pos_x += player.dir_x * player.move_speed;
+			player.pos_y += player.dir_y * player.move_speed;
+		}
+		if (glfwGetKey(window, GLFW_KEY_S) == GLFW_PRESS) {
+			player.pos_x -= player.dir_x * player.move_speed;
+			player.pos_y -= player.dir_y * player.move_speed;
+		}
+		if (glfwGetKey(window, GLFW_KEY_A) == GLFW_PRESS) {
+			// this changes where we're casting our rays
+			double old_dir_x = player.dir_x;
+			player.dir_x = player.dir_x * cos(-player.rot_speed) - player.dir_y * sin(-player.rot_speed);
+			player.dir_y = old_dir_x * sin(-player.rot_speed) + player.dir_y * cos(-player.rot_speed);
+			// this updates perspective
+			double old_plane_x = player.plane_x;
+			player.plane_x = player.plane_x * cos(-player.rot_speed) - player.plane_y * sin(-player.rot_speed);
+			player.plane_y = old_plane_x * sin(-player.rot_speed) + player.plane_y * cos(-player.rot_speed);
+		}
+		if (glfwGetKey(window, GLFW_KEY_D) == GLFW_PRESS) {
+			double old_dir_x = player.dir_x;
+			player.dir_x = player.dir_x * cos(player.rot_speed) - player.dir_y * sin(player.rot_speed);
+			player.dir_y = old_dir_x * sin(player.rot_speed) + player.dir_y * cos(player.rot_speed);
+			double old_plane_x = player.plane_x;
+			player.plane_x = player.plane_x * cos(player.rot_speed) - player.plane_y * sin(player.rot_speed);
+			player.plane_y = old_plane_x * sin(player.rot_speed) + player.plane_y * cos(player.rot_speed);
+		}
+
+
 		glfwSwapBuffers(window);
 		glfwPollEvents();
 
 	}
 
 	glfwTerminate();
+	printf("Terminating program...\n");
 	return 0;
 }