Preliminary Interplanetary Transfers (#2)

.gitignore

@@ -134,3 +134,6 @@ dmypy.json
 
 # VS Code
 .vscode/
+
+# Versioning from setuptools_scm
+src/trajectorize/_version.py

README.md

@@ -9,13 +9,15 @@ KSP Trajectory Optimizer.
 This project is a reduced-scope version of [one of my other (currently incomplete) projects](https://github.com/itchono/gravity-assist-flyby-optimizer), as an intermediate stepping stone.
 
 This tool computes trajectories between celestial bodies in KSP based on on-rails two-body patched conics, incorporating trajectory correction maneuvers for a variety of mission scenarios, such as:
+
 * Ballistic Hohmann transfers for other planets
 * Gravity assist flyby routes
 
 Computationally-intensive code is implemented in C, with a Python wrapper made using `cffi`.
 C code follows mostly C89, with some C99 features used. It has been tested against the latest versions of GCC (on Linux) and MSVC (on Windows 10).
 
 # Installation
+
 The simplest way to install is from PyPI:
 
 `pip install trajectorize`
@@ -35,18 +37,34 @@ The following platforms/compilers have been tested:
 |Ubuntu 20.04 LTS (Dev Machine) | GCC 9.4.0 |
 
 # Demos
+
 Right now, full functionality is incomplete. There are, however, some cool demos showing off the capabilities of the package.
 
 ## Full Model of KSP Planetary System and Ephemerides
+
 `python -m trajectorize.demos.kerbol_system_anim`
 
 ![Kerbol System Animation](https://raw.githubusercontent.com/itchono/trajectorize/assets/kerbol_system.gif)
 
+## Calculation of Ballistic Interplanetary Transfers Using Lambert's Problem
+
+`python -m trajectorize.demos.kerbin_duna_transfer`
+
+![Transfer](https://raw.githubusercontent.com/itchono/trajectorize/assets/kerbin_duna_transfer.png)
+
 ## Propagation of Two-Body Trajectories Using Universal Keplerian Elements
+
 `python -m trajectorize.demos.orbit`
 
 ![Orbit Demo](https://raw.githubusercontent.com/itchono/trajectorize/assets/orbit_universal.png)
 
+## Calculations of Optimal Transfers, Porkchop Plots
+
+`python -m trajectorize.demos.kerbin_duna_porkchop`
+
+![Porkchop](https://raw.githubusercontent.com/itchono/trajectorize/assets/kerbin_duna_porkchop.png)
+
 # Inspirations
+
 * [Interactive illustrated interplanetary guide and calculator for KSP](https://ksp.olex.biz/), by Olex
-* [AlexMoon's Hohmann Transfer Calculator](https://alexmoon.github.io/ksp/), by AlexMoon
+* [Launch Window Planner](https://alexmoon.github.io/ksp/), by AlexMoon

include/conic_kepler.h

@@ -16,10 +16,14 @@ double orbital_period(double semi_major_axis, double mu);
 double theta_from_E(double E, double e);
 double E_from_M(double M, double e);     // Kepler's equation
 double theta_from_M(double M, double e); // Kepler's equation, but with theta instead of E
+double E_from_theta(double theta, double e);
+double M_from_theta(double theta, double e);
+double M_from_E(double E, double e);
 
 KeplerianElements ke_from_state_vector(StateVector state_vector, double mu);
 StateVector state_vector_from_ke(KeplerianElements orbit, double mu);
 StateVectorArray ke_state_locus(KeplerianElements orbit, double mu, int n);
-KeplerianElements ke_orbit_prop(KeplerianElements orbit, double dt, double mu);
+KeplerianElements ke_orbit_prop(double t, KeplerianElements orbit, double mu);
+StateVectorArray ke_orbit_prop_many(int n, double times[], KeplerianElements orbit, double mu);
 
 #endif // CONIC_KEPLER_H

include/delta_v_estimate.h

@@ -0,0 +1,15 @@
+/*
+Trajectorize
+
+Delta v estimator
+*/
+
+#ifndef DELTA_V_ESTIMATE_H
+#define DELTA_V_ESTIMATE_H
+
+#include "kerbol_system_types.h"
+#include "vec_math_types.h"
+
+double delta_v_req(Body body, double excess_velocity, double periapsis);
+
+#endif // DELTA_V_ESTIMATE_H

include/lambert.h

@@ -9,22 +9,23 @@ This header file contains definitions for Lambert's Problem
 #ifndef LAMBERT_H
 #define LAMBERT_H
 
-#include "orbit_math_types.h"
+#include "vec_math_types.h"
 
-typedef struct LambertSolution {
-    double v1[3];
-    double v2[3];
+typedef struct LambertSolution
+{
+    Vector3 v1;
+    Vector3 v2;
     double dt;
 } LambertSolution;
 
 // Lambert's Problem
 
-enum TrajectoryType {
+enum TrajectoryType
+{
     PROGRADE,
     RETROGRADE
 };
 
 LambertSolution lambert(Vector3 R1, Vector3 R2, double dt, double mu, enum TrajectoryType type);
 
-
 #endif // LAMBERT_H

include/rotations.h

@@ -1,4 +1,4 @@
-#include "orbit_math.h"
+#include "vec_math.h"
 
 #ifndef _ROTATIONS_H
 #define _ROTATIONS_H

include/state_vector_types.h

@@ -9,7 +9,7 @@ This file contains typedefs related to state vector types.
 #ifndef STATE_VECTOR_TYPES_H
 #define STATE_VECTOR_TYPES_H
 
-#include "orbit_math_types.h"
+#include "vec_math_types.h"
 
 typedef struct StateVector
 {

include/transfer_orbit.h

@@ -0,0 +1,19 @@
+/*
+Trajectorize
+
+Transfer Orbit Calculator
+
+Header file for functions to calculate transfer orbits between two bodies in the Kerbol system.
+*/
+
+#ifndef TRANSFER_ORBIT_H
+#define TRANSFER_ORBIT_H
+
+#include "keplerian_element_types.h"
+#include "kerbol_system_types.h"
+#include "vec_math_types.h"
+
+KeplerianElements planetary_transfer_orbit(Body body1, Body body2, double t1, double t2);
+Vector3 excess_velocity_at_body(Body body, KeplerianElements transfer_orbit, double ut);
+
+#endif // TRANSFER_ORBIT_H

include/orbit_math.h → include/vec_math.h

@@ -1,21 +1,21 @@
 /*
 Trajectorize
 
-Math Library
+Vector Math Library
 
 This header file contains a library of math functions.
 */
 
-#ifndef ORBIT_MATH_H
-#define ORBIT_MATH_H
+#ifndef VEC_MATH_H
+#define VEC_MATH_H
 
 #include <stdbool.h>
-#include "orbit_math_types.h"
+#include "vec_math_types.h"
 
 double vec_norm(Vector3 v);
 double vec_dot(Vector3 v1, Vector3 v2);
 Vector3 vec_cross(Vector3 v1, Vector3 v2);
-Vector3 vec_normalize(Vector3 v);
+Vector3 vec_normalized(Vector3 v);
 Vector3 vec_zero();
 
 Vector3 vec_add(Vector3 v1, Vector3 v2);
@@ -38,4 +38,4 @@ bool mat_equal(Matrix3 m1, Matrix3 m2);
 void print_vec(Vector3 v);
 void print_mat(Matrix3 m);
 
-#endif // ORBIT_MATH_H
+#endif // VEC_MATH_H

include/orbit_math_types.h → include/vec_math_types.h

@@ -7,8 +7,8 @@ This header file contains typedefs and initializers
 for the various math types used in Trajectorize.
 */
 
-#ifndef ORBIT_MATH_TYPES_H
-#define ORBIT_MATH_TYPES_H
+#ifndef VEC_MATH_TYPES_H
+#define VEC_MATH_TYPES_H
 
 typedef union Vector3
 {
@@ -32,4 +32,4 @@ typedef union Matrix3
     double m[3][3];
 } Matrix3;
 
-#endif // ORBIT_MATH_TYPES_H
+#endif // VEC_MATH_TYPES_H

makefile

@@ -4,6 +4,9 @@ src/trajectorize/_c_extension.so: src/trajectorize/c_ext_utils/build_c_extension
 autoformat:
 	autopep8 --in-place --recursive --aggressive --aggressive src/trajectorize/ -v
 
+plots:
+	bash ./scripts/generate_plots.sh
+
 clean:
 # Remove all .o and .so files under trajectorize/
 # Also remove CFFI generated C files with name like _c_kerbol_system.c

pyproject.toml

@@ -1,3 +1,44 @@
 [build-system]
-requires = ["setuptools>=61", "wheel", "cffi>=1.15.0"]
+requires = [
+    "setuptools>=64",
+    "wheel",
+    "cffi>=1.15.0",
+    "setuptools_scm[toml]>=6.0",
+]
 build-backend = "setuptools.build_meta"
+
+[project]
+name = "trajectorize"
+description = "KSP Trajectory Optimization"
+readme = "README.md"
+requires-python = ">=3.8"
+license = { text = "LGPLv3" }
+authors = [{ name = "Mingde Yin", email = "[email protected]" }]
+maintainers = [{ name = "Mingde Yin", email = "[email protected]" }]
+keywords = ["kerbal space program", "trajectory", "optimization"]
+classifiers = [
+    "Development Status :: 3 - Alpha",
+    "Intended Audience :: Science/Research",
+    "License :: OSI Approved :: GNU Lesser General Public License v3 (LGPLv3)",
+    "Operating System :: OS Independent",
+    "Programming Language :: C",
+    "Programming Language :: Python :: 3",
+    "Programming Language :: Python :: 3.8",
+    "Programming Language :: Python :: 3.9",
+    "Topic :: Scientific/Engineering",
+    "Topic :: Scientific/Engineering :: Mathematics",
+    "Topic :: Scientific/Engineering :: Physics",
+    "Topic :: Scientific/Engineering :: Astronomy",
+]
+dependencies = ["numpy >= 1.23.0", "matplotlib >= 3.4.0", "cffi >= 1.15.0"]
+dynamic = ["version"]
+
+[project.urls]
+homepage = "https://github.com/itchono/trajectorize"
+
+[tool.setuptools.packages.find]
+include = ["trajectorize"]
+where = ["src"]
+
+[tool.setuptools_scm]
+write_to = "src/trajectorize/_version.py"

scripts/generate_plots.sh

@@ -0,0 +1,11 @@
+#!/bin/bash
+
+# Make sure trajectorize is installed
+# Temporarily set env to make matplotlib use Agg backend
+export MPLBACKEND=Agg
+
+# Generate plots
+python -m trajectorize.demos.orbit
+python -m trajectorize.demos.kerbin_duna_transfer
+python -m trajectorize.demos.kerbin_duna_porkchop
+python -m trajectorize.demos.kerbol_system_anim --save

src/trajectorize/__init__.py

@@ -0,0 +1,6 @@
+from importlib.metadata import version, PackageNotFoundError
+
+try:
+    __version__ = version("trajectorize")
+except PackageNotFoundError:
+    __version__ = "unknown version"

src/trajectorize/c_ext_utils/build_c_extension.py

@@ -1,4 +1,5 @@
 import sys
+
 from cffi import FFI
 
 include_dir = "include" if __name__ != "__main__" else "../include"
@@ -39,15 +40,17 @@ def read_and_cleanse_many_headers(*filenames: str) -> str:
 This is because header files further down the list may depend on types defined
 upstream.
 '''
-ffi.cdef(read_and_cleanse_many_headers("orbit_math_types.h",
+ffi.cdef(read_and_cleanse_many_headers("vec_math_types.h",
                                        "state_vector_types.h",
                                        "keplerian_element_types.h",
                                        "kerbol_system_types.h",
                                        "kerbol_system_bodies.h",
                                        "kerbol_system_ephemeris.h",
                                        "conic_kepler.h",
                                        "universal_kepler.h",
-                                       "lambert.h"))
+                                       "lambert.h",
+                                       "transfer_orbit.h",
+                                       "delta_v_estimate.h"))
 
 '''
 Determine compiler flags and linker args depending on platform.
@@ -79,6 +82,8 @@ def read_and_cleanse_many_headers(*filenames: str) -> str:
                #include "conic_kepler.h"
                #include "universal_kepler.h"
                #include "lambert.h"
+               #include "transfer_orbit.h"
+               #include "delta_v_estimate.h"
                ''',
                sources=[f"{src_path}/math_lib/orbit_math.c",
                         f"{src_path}/math_lib/rotations.c",
@@ -87,7 +92,9 @@ def read_and_cleanse_many_headers(*filenames: str) -> str:
                         f"{src_path}/ephemeris/kerbol_system_ephemeris.c",
                         f"{src_path}/orbit/conic_kepler.c",
                         f"{src_path}/orbit/universal_kepler.c",
-                        f"{src_path}/trajectory/lambert.c"],
+                        f"{src_path}/trajectory/lambert.c",
+                        f"{src_path}/trajectory/transfer_orbit.c",
+                        f"{src_path}/trajectory/delta_v_estimate.c"],
                include_dirs=[include_dir],
                extra_compile_args=extra_compile_args)
 

src/trajectorize/c_ext_utils/process_sva_buffer.py

@@ -0,0 +1,17 @@
+import numpy as np
+
+from trajectorize._c_extension import ffi, lib
+
+
+def process_sva_buffer(sva_struct, length: int) -> np.ndarray:
+    # Process memory buffer
+    # Format: [x, y, z, vx, vy, vz, t] x n
+    arr = np.frombuffer(ffi.buffer(sva_struct.mem_buffer, 7 *
+                                   8 * length), dtype=np.float64)
+    arr.shape = (length, 7)
+    copied_arr = np.copy(arr)
+
+    # Free memory
+    lib.free_StateVectorArray(sva_struct)
+
+    return copied_arr