What's a proper way to change colors of a sprite on the fly in libGDX?

Question

I have found a great tutorial series on creating a simple 2D side scroller, Super Mario Brothers, in this case, and I believe I can adapt it fairly well to create a Megaman clone(something I am quite familiar with so that I can focus on learning the code and not necessarily the mechanics).

What has been challenging me is how to swap colors on Megaman when the chosen weapon is changed. I've found a few options, but I am unsure which one is viable.

1. Having each color as a separate sprite sheet
   • PRO:
     • simplest implementation I believe
   • CON:
     • increased footprint size of overall app
2. Converting the texture to a Pixmap, changing the colors I want, convert back to a texture and render as normal?
   • PRO:
     • no increase in app size
   • CON:
     • Is this done on reach render cycle or can I change it once and forget about it until a new weapon change?
3. Shaders
   • PRO:
     • ??
   • CON:
     • From what I am reading, it sounds like they can only change on color at a time? Do I use 2 shaders?
     • They can only be applied wholly to the render and not per sprite?

Thanks.

Answer 1

It seems that doing the pixmap conversion would be your best bet. Especially if your thinking of using alot of colors. Once you convert it back to a texture the colors are retained so you wouldnt need to continuously swap colors during your runtime. If you wanted to, you could even load separate textures for each color before the game starts to save processing time. Shaders could work, but as you said, it would be applied to everything on the screen. But if you were to use some shaders, they could change two colors through frame buffers and such, it would just be really heavy on your game.

Overall, you should go with your pixmap idea. Good luck with your code :)

Answer 2

Another option is to create a black and white or grayscale version of the character spritesheet and then tint it using SpriteBatch.setColor() before rendering the character, based on the appropriate color for the currently equipped weapon.

This option doesn't increase the overall size (like option 1) or memory/cpu usage (like option 2) of the app, and is significantly less complex than option 3 for someone who is learning.

Just make sure you setColor() back to Color.WHITE after drawing the player sprite or everything drawn after that will also be tinted.

Regarding the shader option, it is possible to apply a shader to just a single sprite (sort of), but it would involve rendering the player sprite to an offscreen FrameBufferObject while applying the tinting shader and then compositing that back onto the main scene.

Answer 3

To achieve this behaviour, you should definitely use a specific shader. If you apply the shader to your sprite batch before drawing your sprite and set it back to null, it will just apply to your sprite and not to the entire screen.

You can drive the colours using a few uniforms depending on the power the user have enabled.

See this question for more details:

https://stackoverflow.com/questions/24099103/libgdx-changing-sprite-color-while-hurt

you basically need the same thing with some colour swapping in your shader.

Answer 4

To color your sprite simply use the Sprite#setColor(color) method. This will tint your sprite with the selected color. Make sure to have the parts of your sprite that you want to be colored to be completely white. That way the blending will tint them with 100% of the new color.