How to change the color of a design or a structure or a basic shape ?

Development Character & Animation
1

I know it sounds pretty lame to ask but I really need to know.

I want to make an app, where users get a design or a structure or a basic shape that they can color using the color of their choice by touching and rubbing the screen of their tabs. if they can complete 80% - 90% coloring it then a sound plays and the get to the next lever which has another structure or design.

Can anyone tell me how can I make the painting system?

Thanks in advance.
if I think your ideas are useful then I may hire you.

Thanks in advance.

2

You could try using a render target and render(paint) onto that wherever the player wants.

You could represent a texture in memory (perhaps downsampled from the visual one for performance) and paint onto that.
You would create a array of colours to represent the texture, I don’t know how you can use this in a material.
You would have to look at creating dynamic textures at runtime.

HTH