Particle Engine

[wrightmat]

A basic particle system written in C++ and SDL/OpenGL and configurable from Lua would be a really nice addition to the engine to allow for a variety of advanced graphics effects for the game designer.

Emission features define how, when, and where particles are emitted.

• Continuously generate particles at a fixed rate, or generate a cluster all at once when triggered by some in-game event. [e.g. a bomb exploding]
• Place newly-emitted particles at a point, or randomly within a region, such as a box or circle. The point or region could be moving, e.g. attached to an object or character. [For us, any entity could optionally be an emitter]
• Give the particles a random initial speed and direction, within certain ranges. For example, an explosion would send particles in all directions while a cannon would send them in the direction the cannon is pointing.
• Optionally have particles inherit velocity from their emitter, when the emitter is itself moving.

Motion features control how particles move after they're emitted.

• Collision detection can be used to make particles respect walls, either by flowing along them or bouncing off.
• Air drag causes fast-moving particles to slow down. Gravity or buoyancy makes particles sink or rise. [Probably not useful in a top-down game.]
• Particles also might move along a spline defined by the designer, or be attracted to a particular point or region (possibly attached to an object or character), etc.

Rendering features control how particles look.

• You almost certainly want to have the particles change size, color, and alpha as they age. Animation curves can be defined to control these.
• For a 2D game, the Z-order of particles relative to other game objects should also be controllable. [We could place the particles on any of the 3 existing layers]
• For sprite particles, you might like to have the sprite rotate. It could spin at a random speed, or rotate to face its direction of motion, or the direction its emitter was moving when it was emitted.

Above list is from a post found on Stack Exchange. Some might not apply to solarus, but I think most do.

I also found a good example of a basic particle system written in SDL/C++ which could serve as a starting point. All the code is posted here and he has full YouTube tutorials too.

[wrightmat]

I am now convinced that this could be implemented entirely through Lua scripting and am (slowly) working on it. If small modifications to the engine are required, those will be logged individually.