Tree movement

Newbie & Debugging Questions
#1

Hi,

I have some randomly generated trees in my game (these are sprites). What I want to do is apply some effect which makes the trees
‘bend’ slightly due to wind force. I think this is possible with some simple math:

treeX = (int) (originalTreeX + Math.cos(angle) * windForce);
angle+=0.1;

Problem with this is it would move the whole tree, what I need is this to be applied per pixel, can this be done in the fragment shader?

Thanks

#2

Im not particularly well versed in modern opengl but theoretically you can make a function that takes the height of the pixel in the tree sprite and the wind factor and produces a directly proportional relationship between height and wind. Essentially, if the pixel is higher up in the tree, the wind affects it more

#3

You should use a shader.
But if you dont want to do that you could just have 3 or 4 images for the tree, in each image let the tree be bent slightly more.
Then use the bent images when the wind blows, like an animation.

#4

Thanks guys,

The extra images maybe the way to go for quickness, but fragment shader I’m sure shouldn’t be too difficult…