Slick Forums

Hello, I'm drawing 500 units of an image of rain using drawEmbeded method. I want to rotate the image by 40 to -40 degrees depending on the wind that affects rains but it seems setRotation method doesn't work with drawEmbeded. Is there any way to rotate the image? All the 500 rains should have same degree of rotation, and use the same image. thanks.

Image.setRotation depends on OpenGL's glRotate/glTranslate, which won't work within startUse/endUse (this is simply an OpenGL limitation).

Instead, to rotate within startUse/endUse, you need to transform the vertices before passing them to the GPU.

I've added this functionality to the dev branch on bitbucket: Image.drawEmbedded(x, y, width, height, rotation)

The downside is that it needs to perform the rotation transform every time you call drawEmbedded. If you are finding this to be a bottleneck (which it probably won't be...) then you can use something like this utility which would allow you to store the transformed vertices instead of calculating the rotation more than necessary.

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For those wondering:
Why overload with a rotation parameter when Image has setRotation/getRotation? Here's my rationale for overloading and ignoring getRotation: (a) IMO it is a design flaw to have Image store things like alpha/rotation, (b) drawEmbedded has never relied on getAlpha/getRotation in the past, (c) to maintain consistency with the drawEmbedded method which draws a sub image (i.e. a "fresh copy" so to speak, as if we used getSubImage to draw).

The Image class is a bit of a mess; I'm doing what I can to clean it up when I have time.

Thank you that utility class worked Before using that, I tried preparing rotated image by calling the method below, before start drawing 500 rains with drawEmbeded but somehow it lowered my FPS greatly.



Anyway xD Could you possibly add scaling feature to the utility like Image class' drawEmbedded(float x, float y, float width, float height)? I still can't seem to understand native openGL codes much.

Why not just use the drawEmbedded method which was added to Image in the dev branch? There are also a lot of other bug fixes going on that would be worth adding to your project.

Now that it's in the Slick codebase, the utility class I had earlier is obsolete (unless you are running into a CPU bottleneck when rotating the vertices, which seems unlikely).

I think I'm going to try the one in the dev branch. Might be a silly question but do you have to build the dev version yourself and make whole set of jar files like the slick2d official releases has to use it? Or you can just use specific class? I'm not sure how everyone is doing it

I'm not sure how everyone else is doing it either. I go to this url: https://bitbucket.org/kevglass/slick . Then I click "branches >> development" Finally, I click "sources >> zip" to download a zip file that contains the entire library. I make a new project with the source files and compile the jars myself.

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