Bump version to v0.6

This should help to better visualize the velocity of the ship.

CHANGELOG.md

@@ -1,5 +1,16 @@
 # Change Log
 
+## v0.6: Planetary Masses
+
+- Add planetary masses.
+- Modify some of the constants.
+
+## v0.5: Effects
+
+- Added stars in background for a better sense of velocity.
+- Viewport follows ship at center.
+- Zoom functionality.
+
 ## v0.4: More functionality
 
 - Fix acceleration.

CMakeLists.txt

@@ -18,7 +18,7 @@ cmake_minimum_required(VERSION 3.10)
 project(SpaceShipSim C)
 
 set(TARGET_NAME "spaceshipsim")
-set(TARGET_VERSION "0.4")
+set(TARGET_VERSION "0.6")
 
 if(NOT CMAKE_BUILD_TYPE)
 	set(CMAKE_BUILD_TYPE "release")
@@ -44,7 +44,9 @@ include_directories(
 set(SRCS
 	src/event_manager.c
 	src/main.c
-	src/ship.c)
+	src/planet.c
+	src/ship.c
+	src/starfield.c)
 
 add_definitions(-DVERSION="${TARGET_VERSION}")
 

TODO

@@ -1,2 +0,0 @@
-TODO:
- - Add presets with stellar masses (for gravity simulation).

src/event_manager.c

@@ -1,6 +1,6 @@
 /*
- * Copyright (C) 2018  Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
+ * Copyright (C) 2018,2026  Ortega Froysa, Nicolás <nicolas@ortegas.org>
- * Author: Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
+ * Author: Ortega Froysa, Nicolás <nicolas@ortegas.org>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -104,6 +104,13 @@ void set_key(int keycode, int value) {
 		case ALLEGRO_KEY_P:
 			keys[KEY_PAUSE] = value;
 			break;
+		case ALLEGRO_KEY_LSHIFT:
+		case ALLEGRO_KEY_RSHIFT:
+			keys[KEY_SHIFT] = value;
+			break;
+		case ALLEGRO_KEY_Z:
+			keys[KEY_ZOOM] = value;
+			break;
 		default:
 			break;
 	}

src/event_manager.h

@@ -1,6 +1,6 @@
 /*
- * Copyright (C) 2018  Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
+ * Copyright (C) 2018,2026  Ortega Froysa, Nicolás <nicolas@ortegas.org>
- * Author: Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
+ * Author: Ortega Froysa, Nicolás <nicolas@ortegas.org>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -28,7 +28,9 @@ enum {
 	KEY_RESET       = 0x4,
 	KEY_FULLSCREEN  = 0x5,
 	KEY_PAUSE       = 0x6,
-	KEY_MAX         = 0x7
+	KEY_ZOOM        = 0x7,
+	KEY_SHIFT       = 0x8,
+	KEY_MAX         = 0x9
 };
 
 /**

src/globals.h

@@ -1,6 +1,6 @@
 /*
- * Copyright (C) 2018  Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
+ * Copyright (C) 2018,2026  Ortega Froysa, Nicolás <nicolas@ortegas.org>
- * Author: Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
+ * Author: Ortega Froysa, Nicolás <nicolas@ortegas.org>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -26,7 +26,7 @@
 #	define FPS 60.0f
 #endif
 #ifndef ACCEL
-#	define ACCEL 0.1f
+#	define ACCEL 0.3f
 #endif
 #ifndef TURN_ACCEL
 #	define TURN_ACCEL (M_PI / FPS)  // turn at pi radians / sec
@@ -39,6 +39,16 @@
 #	define WINDOW_HEIGHT 600
 #endif
 
+#ifndef ZOOM_MIN
+#	define ZOOM_MIN 0.25f
+#endif
+#ifndef ZOOM_MAX
+#	define ZOOM_MAX 4.0f
+#endif
+#ifndef ZOOM_STEP
+#	define ZOOM_STEP 0.1f
+#endif
+
 #include <math.h>
 #ifndef M_PI
 #	define M_PI 3.14159265f

src/main.c

@@ -1,6 +1,6 @@
 /*
- * Copyright (C) 2018  Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
+ * Copyright (C) 2018,2026  Ortega Froysa, Nicolás <nicolas@ortegas.org>
- * Author: Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
+ * Author: Ortega Froysa, Nicolás <nicolas@ortegas.org>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -19,6 +19,8 @@
 #include "globals.h"
 #include "event_manager.h"
 #include "ship.h"
+#include "starfield.h"
+#include "planet.h"
 
 int run;
 int redraw;
@@ -39,6 +41,8 @@ const char *help =
 	"I - show/hide simulation information\n"
 	"H - show/hide this help information\n"
 	"F - toggle fullscreen\n"
+	"Z - zoom in\n"
+	"SHIFT+Z - zoom out\n"
 	"Q/ESC - quit";
 
 const char *info_format =
@@ -51,6 +55,10 @@ const char *info_format =
 
 int main() {
 	char title[32];
+	float zoom = 1.0f;
+	float display_width = WINDOW_WIDTH;
+	float display_height = WINDOW_HEIGHT;
+
 	sprintf(title, "SpaceShipSim v%s", VERSION);
 	puts(title);
 
@@ -99,6 +107,10 @@ int main() {
 	struct ship ship;
 	ship_init(&ship, 400, 300);
 
+	// initialize the planet
+	struct planet planet;
+	planet_init(&planet, 400.0f, 300.0f, 250.0f);
+
 	ALLEGRO_FONT *font = al_create_builtin_font();
 
 	// begin running the simulation
@@ -109,6 +121,7 @@ int main() {
 	int paused = 0;
 	int old_paused = 0;
 	int just_toggled_fullscreen = 0;
+	int zoom_pressed = 0;
 	while(run)
 	{
 		handle_event();
@@ -116,6 +129,12 @@ int main() {
 		// only redraw or run simulation if the timer event has occurred
 		if(redraw)
 		{
+			if(just_toggled_fullscreen)
+			{
+				display_width = al_get_display_width(display);
+				display_height = al_get_display_height(display);
+			}
+
 			if(paused == old_paused && key_is_down(KEY_PAUSE))
 				paused = !paused;
 			else if(paused != old_paused && !key_is_down(KEY_PAUSE))
@@ -124,9 +143,13 @@ int main() {
 			if(!paused)
 			{
 				if(key_is_down(KEY_RESET))
-					ship_init(&ship, WINDOW_WIDTH / 2, WINDOW_HEIGHT / 2);
+					ship_init(&ship, (float)WINDOW_WIDTH / 2, (float)WINDOW_HEIGHT / 2);
 				else
-					ship_update(&ship);
+				{
+					float gravity_x, gravity_y;
+					planet_get_gravity(&planet, ship.x, ship.y, &gravity_x, &gravity_y);
+					ship_update(&ship, gravity_x, gravity_y);
+				}
 			}
 
 			if (key_is_down(KEY_FULLSCREEN) && !just_toggled_fullscreen)
@@ -146,8 +169,42 @@ int main() {
 				just_toggled_fullscreen = 0;
 			}
 
+			if(key_is_down(KEY_SHIFT) && key_is_down(KEY_ZOOM) && !zoom_pressed)
+			{
+				zoom -= ZOOM_STEP;
+				if(zoom < ZOOM_MIN)
+					zoom = ZOOM_MIN;
+				zoom_pressed = 1;
+			}
+			else if(key_is_down(KEY_ZOOM) && !zoom_pressed)
+			{
+				zoom += ZOOM_STEP;
+				if(zoom > ZOOM_MAX)
+					zoom = ZOOM_MAX;
+				zoom_pressed = 1;
+			}
+			else if(!key_is_down(KEY_ZOOM) && zoom_pressed)
+			{
+				zoom_pressed = 0;
+			}
+
 			al_clear_to_color(al_map_rgb(0, 0, 0));
+
+			ALLEGRO_TRANSFORM transform;
+			al_identity_transform(&transform);
+			al_scale_transform(&transform, zoom, zoom);
+			al_translate_transform(&transform,
+					display_width / 2.0f - ship.x * zoom,
+					display_height / 2.0f - ship.y * zoom);
+			al_use_transform(&transform);
+
+			starfield_draw(ship.x, ship.y, zoom, display_width, display_height);
+			planet_draw(&planet);
 			ship_draw(&ship);
+
+			al_identity_transform(&transform);
+			al_use_transform(&transform);
+
 			if(show_info)
 			{
 				char info[256];
@@ -158,7 +215,7 @@ int main() {
 						ship.velX * FPS, ship.velY * FPS);
 				al_draw_multiline_text(font,
 						al_map_rgb(0xFF, 0xFF, 0xFF),
-						5, 5, WINDOW_WIDTH, 10.0f,
+						5, 5, (int)display_width, 10.0f,
 						ALLEGRO_ALIGN_LEFT,
 						info);
 			}
@@ -167,8 +224,8 @@ int main() {
 			{
 				al_draw_multiline_text(font,
 						al_map_rgb(0xFF, 0xFF, 0xFF),
-						(float)WINDOW_WIDTH / 2, (float)WINDOW_HEIGHT / 2 - 50,
+						display_width / 2, display_height / 2 - 50,
-						WINDOW_WIDTH, 10.0f,
+						(int)display_width, 10.0f,
 						ALLEGRO_ALIGN_CENTRE,
 						help);
 			}

src/planet.c

@@ -0,0 +1,78 @@
+/*
+ * Copyright (C) 2026  Ortega Froysa, Nicolás <nicolas@ortegas.org>
+ * Author: Ortega Froysa, Nicolás <nicolas@ortegas.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "planet.h"
+#include <math.h>
+#include <assert.h>
+#include <allegro5/allegro_primitives.h>
+
+#define GRAVITY_CONSTANT 1.0f  // Gravitational constant scaled for simulation
+#define SHIP_MASS 1.0f           // Assumed constant ship mass
+#define MASS_TO_RADIUS 1.5f      // Radius scale factor: radius = MASS_TO_RADIUS * mass^(1/3)
+
+void planet_init(struct planet *planet, float x, float y, float mass) {
+	assert(planet);
+
+	planet->x = x;
+	planet->y = y;
+	planet->mass = mass;
+	planet->radius = MASS_TO_RADIUS * cbrtf(planet->mass);
+}
+
+void planet_get_gravity(struct planet *planet, float ship_x, float ship_y,
+						float *accel_x, float *accel_y) {
+	assert(planet);
+	assert(accel_x);
+	assert(accel_y);
+
+	float dx = planet->x - ship_x;
+	float dy = planet->y - ship_y;
+	float distance = sqrtf(dx * dx + dy * dy);
+
+	if(distance < planet->radius) {
+		*accel_x = 0.0f;
+		*accel_y = 0.0f;
+		return;
+	}
+
+	// F = G * m1 * m2 / r^2
+	float force = GRAVITY_CONSTANT * SHIP_MASS * planet->mass / (distance * distance);
+
+	// a = F / m_ship = G * m_planet / r^2
+	float acceleration = force / SHIP_MASS;
+
+	// Normalize direction and apply acceleration
+	float norm_x = dx / distance;
+	float norm_y = dy / distance;
+
+	*accel_x = norm_x * acceleration;
+	*accel_y = norm_y * acceleration;
+}
+
+void planet_draw(struct planet *planet) {
+	assert(planet);
+
+	// Color intensity based on mass (brighter = more massive)
+	float color_scale = fminf(1.0f, planet->mass / 1000.0f);
+	int r = (int)(100 + 155 * color_scale);
+	int g = (int)(100 + 50 * color_scale);
+	int b = (int)(150 - 100 * color_scale);
+
+	al_draw_filled_circle(planet->x, planet->y, planet->radius,
+			al_map_rgb(r, g, b));
+}

src/planet.h

@@ -0,0 +1,62 @@
+/*
+ * Copyright (C) 2026  Ortega Froysa, Nicolás <nicolas@ortegas.org>
+ * Author: Ortega Froysa, Nicolás <nicolas@ortegas.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+/**
+ * Function pointer type for calculating planet mass.
+ * Takes no parameters and returns the mass value.
+ */
+typedef float (*planet_mass_func)(void);
+
+struct planet {
+	float x, y;       ///< The x and y coordinates of the planet center.
+	float mass;       ///< The mass of the planet.
+	float radius;     ///< The radius of the planet (derived from mass).
+};
+
+/**
+ * @brief Initialize a planet at a position with a specified mass.
+ *
+ * @param planet A pointer to the planet object.
+ * @param x Initial x position of the planet center.
+ * @param y Initial y position of the planet center.
+ * @param mass The mass of the planet.
+ */
+void planet_init(struct planet *planet, float x, float y, float mass);
+
+/**
+ * @brief Calculate the gravitational acceleration on a ship at a given position.
+ *
+ * Returns the acceleration vector components due to the planet's gravity.
+ *
+ * @param planet A pointer to the planet object.
+ * @param ship_x X position of the ship.
+ * @param ship_y Y position of the ship.
+ * @param accel_x Pointer to store the x component of acceleration.
+ * @param accel_y Pointer to store the y component of acceleration.
+ */
+void planet_get_gravity(struct planet *planet, float ship_x, float ship_y,
+						float *accel_x, float *accel_y);
+
+/**
+ * @brief Draw the planet.
+ *
+ * @param planet Planet object to draw.
+ */
+void planet_draw(struct planet *planet);

src/ship.c

@@ -1,6 +1,6 @@
 /*
- * Copyright (C) 2018  Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
+ * Copyright (C) 2018,2026  Ortega Froysa, Nicolás <nicolas@ortegas.org>
- * Author: Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
+ * Author: Ortega Froysa, Nicolás <nicolas@ortegas.org>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -23,11 +23,10 @@
 #include <math.h>
 #include <assert.h>
 #include <allegro5/allegro_primitives.h>
-#include <stdio.h>
 
 #define SHIP_RADIUS 10.0f  // radius of the ship in pixels
 
-void ship_init(struct ship *ship, int x, int y) {
+void ship_init(struct ship *ship, float x, float y) {
 	assert(ship);
 	ship->x = x;
 	ship->y = y;
@@ -35,7 +34,7 @@ void ship_init(struct ship *ship, int x, int y) {
 	ship->direction = 0;
 }
 
-void ship_update(struct ship *ship) {
+void ship_update(struct ship *ship, float gravity_x, float gravity_y) {
 	assert(ship);
 
 	if(key_is_down(KEY_RIGHT))
@@ -61,6 +60,10 @@ void ship_update(struct ship *ship) {
 		ship->velY -= sin(ship->direction) * (ACCEL / 2);
 	}
 
+	// Apply gravitational acceleration
+	ship->velX += gravity_x;
+	ship->velY += gravity_y;
+
 	ship->x += ship->velX;
 	ship->y += ship->velY;
 }

src/ship.h

@@ -1,6 +1,6 @@
 /*
- * Copyright (C) 2018  Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
+ * Copyright (C) 2018,2026  Ortega Froysa, Nicolás <nicolas@ortegas.org>
- * Author: Ortega Froysa, Nicolás <nortega@themusicinnoise.net>
+ * Author: Ortega Froysa, Nicolás <nicolas@ortegas.org>
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -37,15 +37,17 @@ struct ship {
  * @param x Initial x position of the ship.
  * @param y Initial y position of the ship.
  */
-void ship_init(struct ship *ship, int x, int y);
+void ship_init(struct ship *ship, float x, float y);
 
 /**
  * @brief Updates the ship's variables according to keyboard
- * input.
+ * input and gravitational forces.
  *
  * @param ship A pointer to the ship object.
+ * @param gravity_x Gravitational acceleration in x direction.
+ * @param gravity_y Gravitational acceleration in y direction.
  */
-void ship_update(struct ship *ship);
+void ship_update(struct ship *ship, float gravity_x, float gravity_y);
 
 /**
  * @brief Draw the ship.

src/starfield.c

@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2026  Ortega Froysa, Nicolás <nicolas@ortegas.org>
+ * Author: Ortega Froysa, Nicolás <nicolas@ortegas.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "starfield.h"
+#include "globals.h"
+
+#include <stdlib.h>
+#include <math.h>
+#include <allegro5/allegro.h>
+#include <allegro5/allegro_primitives.h>
+
+#define CHUNK_SIZE 256
+#define STARS_PER_CHUNK 50
+#define STAR_COLOR al_map_rgb(255, 255, 255)
+
+static unsigned int hash_seed(int chunk_x, int chunk_y) {
+	unsigned int h = 5381;
+	h = ((h << 5) + h) ^ chunk_x;
+	h = ((h << 5) + h) ^ chunk_y;
+	return h;
+}
+
+static void generate_chunk_stars(int chunk_x, int chunk_y) {
+	unsigned int seed = hash_seed(chunk_x, chunk_y);
+	srand(seed);
+
+	float base_x = chunk_x * CHUNK_SIZE;
+	float base_y = chunk_y * CHUNK_SIZE;
+
+	for(int i = 0; i < STARS_PER_CHUNK; ++i)
+	{
+		float star_x = base_x + (float)(rand() % CHUNK_SIZE);
+		float star_y = base_y + (float)(rand() % CHUNK_SIZE);
+
+		al_draw_pixel(star_x, star_y, STAR_COLOR);
+	}
+}
+
+void starfield_draw(float camera_x, float camera_y, float zoom, float width, float height) {
+	float view_width = width / zoom;
+	float view_height = height / zoom;
+
+	float left = camera_x - view_width / 2.0f;
+	float right = camera_x + view_width / 2.0f;
+	float top = camera_y - view_height / 2.0f;
+	float bottom = camera_y + view_height / 2.0f;
+
+	int chunk_left = (int)floor(left / CHUNK_SIZE);
+	int chunk_right = (int)floor(right / CHUNK_SIZE);
+	int chunk_top = (int)floor(top / CHUNK_SIZE);
+	int chunk_bottom = (int)floor(bottom / CHUNK_SIZE);
+
+	for(int cy = chunk_top; cy <= chunk_bottom; ++cy)
+	{
+		for(int cx = chunk_left; cx <= chunk_right; ++cx)
+		{
+			generate_chunk_stars(cx, cy);
+		}
+	}
+}

src/starfield.h

@@ -0,0 +1,30 @@
+/*
+ * Copyright (C) 2026  Ortega Froysa, Nicolás <nicolas@ortegas.org>
+ * Author: Ortega Froysa, Nicolás <nicolas@ortegas.org>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+/**
+ * @brief Draw stars in the visible area of the starfield.
+ *
+ * @param camera_x The x position of the camera center.
+ * @param camera_y The y position of the camera center.
+ * @param zoom The zoom level (scale factor).
+ * @param width The display width in pixels.
+ * @param height The display height in pixels.
+ */
+void starfield_draw(float camera_x, float camera_y, float zoom, float width, float height);