Working barebones heightmap renderer

1 files changed, 285 insertions, 0 deletions

diff --git a/simple-raycaster/src/main.c b/simple-raycaster/src/main.c
new file mode 100644
index 0000000..cbe13d8
--- /dev/null
+++ b/simple-raycaster/src/main.c
@@ -0,0 +1,285 @@
+#include <GL/glew.h> // must come before glfw3
+#include <GLFW/glfw3.h>
+#include <stdio.h>
+#include <math.h>
+
+#include "player.h"
+
+// TODO: move to implicit map definition with level editor in future
+#define MAP_HEIGHT 20
+#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, 2, 2, 2, 0, 0, 0, 0, 1},
+    {1, 0, 2, 2, 2, 0, 0, 0, 0, 1},
+    {1, 0, 2, 2, 2, 0, 0, 0, 0, 1},
+    {1, 0, 2, 2, 2, 0, 0, 0, 0, 1},
+    {1, 0, 2, 2, 2, 0, 4, 4, 0, 1},
+    {1, 0, 0, 0, 0, 0, 4, 4, 0, 1},
+    {1, 0, 0, 0, 0, 0, 4, 4, 0, 1},
+    {1, 0, 0, 0, 0, 0, 4, 4, 0, 1},
+    {1, 0, 0, 0, 0, 0, 4, 4, 0, 1},
+    {1, 0, 0, 0, 0, 0, 4, 4, 0, 1},
+    {1, 0, 0, 0, 0, 0, 4, 4, 0, 1},
+    {1, 0, 3, 3, 3, 0, 4, 4, 0, 1},
+    {1, 0, 3, 3, 3, 0, 0, 0, 0, 1},
+    {1, 0, 3, 3, 3, 0, 0, 0, 0, 1},
+    {1, 0, 3, 3, 3, 0, 0, 0, 0, 1},
+    {1, 0, 3, 3, 3, 0, 0, 0, 0, 1},
+    {1, 0, 0, 0, 0, 0, 0, 0, 0, 1},
+    {1, 1, 1, 1, 1, 1, 1, 1, 1, 1},
+};
+
+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, GLubyte *pixels, int width, int height) {
+    	int screen_width = width;
+    	int screen_height = height;
+
+    	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; }
+
+		// fog effect
+		float fog_distance = 15.0f;
+		float scale_factor = 1.0f - perp_wall_dist / fog_distance;
+		if (scale_factor < 0.0f) { scale_factor = 0.0f; }
+		
+		// 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; }
+		int pitch = screen_height / 2 * player->look_angle;
+		int start_y = -line_height / 2 + screen_height / 2 + pitch;
+		if (start_y < 0) { start_y = 0; }
+		int end_y = line_height / 2 + screen_height / 2 + pitch;
+		if (end_y >= screen_height) { end_y = screen_height - 1; }
+
+
+		// colors :)
+		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;
+		}
+
+		// scale brightness in accordance with distance (for fog)
+		color.r *= scale_factor;
+		color.g *= scale_factor;
+		color.b *= scale_factor;
+
+		int index;
+		for (int y = 0; y < screen_height; y++) {
+			index = y * screen_width * 3 + x * 3;
+			if (y >= start_y && y <= end_y) {
+				// draw something
+				pixels[index] = color.r;
+				pixels[index+1] = color.g;
+				pixels[index+2] = color.b;
+			} else {
+				// fill blank space
+				pixels[index] = 0;	
+				pixels[index+1] = 0;	
+				pixels[index+2] = 0;	
+			}
+		}
+
+    	}
+}
+
+int main(int argc, char *argv[]) {
+	GLFWwindow* window;
+
+	double mouse_x;
+	double mouse_y;
+
+	// init player
+	Player player;
+	player.pos_y = 2.0f;
+	player.pos_x = 9.0f;
+	player.dir_x = 1.0f;
+	player.dir_y = 0.0f;
+	player.plane_x = 0.20f; // FOV related
+	player.plane_y = 0.90f; // FOV related
+	player.look_angle = 0.0f;
+	player.move_speed = 0.035f;
+	player.sensitivity = 0.001f;
+
+	// initiate glfw library
+	if (!glfwInit()){
+		printf("Failed to initiate GLFW.\n");
+		return -1;
+	}
+
+	// create glfw window
+	GLFWmonitor* primary = glfwGetPrimaryMonitor();
+	const GLFWvidmode* mode = glfwGetVideoMode(primary);
+	//window = glfwCreateWindow(800, 600, "raycaster", NULL, NULL);
+	window = glfwCreateWindow(mode->width, mode->height, "raycaster", primary, NULL);
+	if (!window){
+		printf("Failed to create GLFW window.\n");
+		glfwTerminate();
+		return -1;
+	}
+
+	// make window current
+	glfwMakeContextCurrent(window);
+	glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
+
+	// update mouse position
+	// glfwGetCursorPos(window, &mouse_x, &mouse_y);
+	mouse_x -= mode->width / 2;
+	mouse_y -= mode->height / 2;
+
+	// setup orthographic projection camera
+	glMatrixMode(GL_PROJECTION);
+	glLoadIdentity();
+	glOrtho(0.0, mode->width, mode->height, 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];
+
+	// setup pbo for optimized performance
+	if (glewInit() != GLEW_OK) { 
+		printf("Failed to initiate GLEW.\n");
+		return -1;
+	}
+	GLuint pbo = 0;
+
+	glGenBuffers(1, &pbo);
+	glBindBuffer(GL_PIXEL_UNPACK_BUFFER, pbo);
+	glBufferData(GL_PIXEL_UNPACK_BUFFER, mode->width * mode->height * 3, 0, GL_STREAM_DRAW);
+
+	int index = 0;
+	glViewport(0, 0, mode->width, mode->height);
+	while (!glfwWindowShouldClose(window)) {
+
+		// Stop loop if window isn't focused
+		if(!glfwGetWindowAttrib(window, GLFW_FOCUSED)){
+			continue;
+		}
+
+		// 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
+        float prev_position[2] = {player.pos_x, player.pos_y};
+		move_player(&player, window, &mouse_x, &mouse_y, mode->width, mode->height);
+        if (world_map[(int)player.pos_x][(int)player.pos_y] != 0) {
+            player.pos_x = prev_position[0];
+            player.pos_y = prev_position[1];
+        }
+		GLubyte* pixels = (GLubyte*)glMapBuffer(GL_PIXEL_UNPACK_BUFFER, GL_WRITE_ONLY);
+		raycast(&player, pixels, mode->width, mode->height);
+
+		// pbo
+		glUnmapBuffer(GL_PIXEL_UNPACK_BUFFER);
+		glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+		glPixelStorei(GL_UNPACK_ROW_LENGTH, mode->width);
+		glWindowPos2i(0, 0);
+		glDrawPixels(mode->width, mode->height, GL_RGB, GL_UNSIGNED_BYTE, 0);
+
+		
+		glfwSwapBuffers(window);
+		glfwPollEvents();
+
+	}
+
+	printf("Terminating GLFW...\n");
+	glfwTerminate();
+	printf("Clearing buffer...\n");
+	glDeleteBuffers(1, &pbo);
+	return 0;
+
+}