Rewrite parts of CMakeLists.txt.

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

@@ -15,10 +15,12 @@
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
 cmake_minimum_required(VERSION 3.10)
-project(SpaceShipSim C)
-
-set(TARGET_NAME "spaceshipsim")
-set(TARGET_VERSION "0.4")
+project(spaceshipsim
+	VERSION 0.6
+	SPDX_LICENSE "GPL-3.0-or-later"
+	DESCRIPTION "A simulation of a 2D space ship in the frictionless environment of space."
+	HOMEPAGE_URL "https://code.ortegas.org/nortega/spaceshipsim"
+	LANGUAGES C)
 
 if(NOT CMAKE_BUILD_TYPE)
 	set(CMAKE_BUILD_TYPE "release")
@@ -42,12 +44,22 @@ include_directories(
 	SYSTEM ${ALLEG5_INCLUDE_DIRS})
 
 set(SRCS
-	src/event_manager.c
-	src/main.c
-	src/ship.c
-	src/starfield.c)
+	"src/event_manager.c"
+	"src/main.c"
+	"src/planet.c"
+	"src/ship.c"
+	"src/starfield.c"
+)
 
-add_definitions(-DVERSION="${TARGET_VERSION}")
+set(HDRS
+	"src/event_manager.h"
+	"src/globals.h"
+	"src/planet.h"
+	"src/ship.h"
+	"src/starfield.h"
+)
+
+add_definitions(-DVERSION="${PROJECT_VERSION}")
 
 if(${CMAKE_BUILD_TYPE} STREQUAL "debug" OR ${CMAKE_BUILD_TYPE} STREQUAL "relwithdebinfo")
 	add_definitions(-DDEBUG)
@@ -55,14 +67,14 @@ else()
 	add_definitions(-DNDEBUG)
 endif()
 
-add_executable(${TARGET_NAME} ${SRCS})
+add_executable(${PROJECT_NAME} ${SRCS} ${HDRS})
 
-target_link_libraries(${TARGET_NAME}
+target_link_libraries(${PROJECT_NAME}
 	m  # math library
 	${ALLEG5_LIBRARIES}
 	${ALLEG5-PRIM_LIBRARIES}
 	${ALLEG5-FONT_LIBRARIES})
 
-install(TARGETS ${TARGET_NAME}
+install(TARGETS ${PROJECT_NAME}
 	RUNTIME DESTINATION bin/
 	CONFIGURATIONS release minsizerel)

TODO

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

src/globals.h

@@ -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

src/main.c

@@ -20,6 +20,7 @@
 #include "event_manager.h"
 #include "ship.h"
 #include "starfield.h"
+#include "planet.h"
 
 int run;
 int redraw;
@@ -55,6 +56,9 @@ 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);
 
@@ -103,6 +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
@@ -121,6 +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))
@@ -129,9 +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)
@@ -176,11 +194,12 @@ int main() {
 			al_identity_transform(&transform);
 			al_scale_transform(&transform, zoom, zoom);
 			al_translate_transform(&transform,
-					WINDOW_WIDTH / 2.0f - ship.x * zoom,
-					WINDOW_HEIGHT / 2.0f - ship.y * zoom);
+					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);
+			starfield_draw(ship.x, ship.y, zoom, display_width, display_height);
+			planet_draw(&planet);
 			ship_draw(&ship);
 
 			al_identity_transform(&transform);
@@ -196,7 +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);
 			}
@@ -205,8 +224,8 @@ int main() {
 			{
 				al_draw_multiline_text(font,
 						al_map_rgb(0xFF, 0xFF, 0xFF),
-						(float)WINDOW_WIDTH / 2, (float)WINDOW_HEIGHT / 2 - 50,
-						WINDOW_WIDTH, 10.0f,
+						display_width / 2, display_height / 2 - 50,
+						(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

@@ -26,7 +26,7 @@
 
 #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;
@@ -34,7 +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))
@@ -60,6 +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

@@ -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

@@ -51,9 +51,9 @@ static void generate_chunk_stars(int chunk_x, int chunk_y) {
 	}
 }
 
-void starfield_draw(float camera_x, float camera_y, float zoom) {
-	float view_width = WINDOW_WIDTH / zoom;
-	float view_height = WINDOW_HEIGHT / zoom;
+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;

src/starfield.h

@@ -24,5 +24,7 @@
  * @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);
+void starfield_draw(float camera_x, float camera_y, float zoom, float width, float height);