Hello, I’m quite new, and I have a problem.
Generally speaking, what I’m trying to do is Photoshop’s stamp tool. For those who don’t know what it is, it’s a tool which takes pixels from one part of the images and copies them somewhere else using a brush, which may be any alpha shape.
I’ve done it, but stumbled upon performance issues. I guess there’s a way to make it better.
What I’m doing:
- My brush (B) is a two-dimensional array with float values for each pixel. [0.0, 1.0]
- The image is a surface (S1) AND a texture (T1). I change T1 only once, when I’m done with painting.
- There is a second surface (S2), which is used to paint stuff over S1.
- As long as a mouse button is down, I copy pixels from S1 to S2 using a vector and B as alpha.
This step causes performance issues. I convert S2 to a texture (T2) every single time mouse moves as long as a button is down.
- I render T1, then T2
- As soon as a mouse button is up, I merge S2 and T1.
As a pseudocode:
Mouse position _position_;
Mouse position difference _dpos_ = |old_position - position|;
Mouse button _button_;
Brush _brush_ as a two-dimensional array with values [0.0, 1.0];
Vector _vec_ that defines where to copy from;
Surface S1, S2;
Texture T1, T2;
if button down then do
if(dpos>0) then do
for each pixel(x,y) in brush down
S2(position + (x,y)) <- S1(position + (x,y) - vec) * pixel(x,y)
T2 <- S2 // this step causes performance issues
if S2 not empty then do
S1 <- T1 + T2
T1 <- S1
I know that it slows down because I continuously move things from CPU/RAM to GPU. I’m not sure how to avoid that though.I though about creating a second texture with a shift and paint a white mask instead of texture, but I would still need to make Surface to Texture conversion every single mouse move.