fangj99/opengl-c-solarsystem

Animated solar system model implemented with OpenGL and FreeGLUT in C

Solar System

This is an animated solar system model implemented with OpenGL and FreeGLUT in C.

Screenshot

Features

• Texture.
• Lighting.
• Camera moving.
• Sun, eight planets and moon.
• Axis tilt and orbit inclination (Visualizing the formation of midnight sun).
• Astronomical data from Wikipedia.

Usage

• Preset views:
  • 1/2: Far / near top-down view.
  • 3/4: Far / near perspective view.
  • 5/6: Far / near view at ecliptic.
  • 7/8: Far / near perspective view on x-axis.
• Viewport:
  • W/S: Forward / backward.
  • A/D: Left / right.
  • Q/E: Up / down.
  • Mouse wheel: Forward / backward.
  • Mouse dragging: Move scene around camera.
• Rotation:
  • -/(+/=): Time forward / backward.
  • [/]: Speed up / down. This also has an influence on current time.
• Debugging:
  • P: Print viewport vectors.

Texture

Texture are taken from solarsystemscope.com which are licensed under CC BY 3.0, and exported in TGA format for use.

Lighting

Lighting is implemented with glLightfv(), a point light source positioned at the center of sun. Since sun itself is a light-emitting object, its lighting is simply turned off.

Camera moving

gluLookAt() is used for the viewing matrix, while the program keeps track of the eye position, look direction and up direction vectors. Keyboard and mouse input adjust these values accordingly.

Data

Astronomical data are taken from the planet pages on Wikipedia. In order to keep the size and offset of this model reasonable, values are scaled by functions to present a sensible rendering, while maintaining their relative magnitude.

You can get an impression of the actual scale of solar system at If the Moon Were Only 1 Pixel.

Both physical and orbital data of every planet is kept as a body_t, with a null-terminated body_t * array field containing its children. They are initialized as globals at the beginning of the program.