I'm trying to draw on the screen the subimage of an Image instance using this subimage method. It seems to be pretty straight forward to do it but when I call the function it returns a NilClass instead of a new Image.
The main image is defined as:
@bg_img = Gosu::Image.new("res/space1.jpg") # dimensions 1080 x 1920
when I run @bg_img.draw(0,0,0) it draws the image normally, but when I I try to cast it into a new image:
test = @bg_img.subimage(0,0, 100, 100) # from (0,0), get rectangle of 100x100 dimension
The variable test is assigned with a null and therefore can't .draw it. Am I doing something wrong here? Or, is there another way to draw the subimage? Thanks in advance.
You can only use .subimage() if your image is 1024 x 1024 or smaller. I'm not sure if there's a work-around, but because this limit is inspired by memory constraints, you would probably be better off just splitting your image into multiple images of size 512 x 512 or 1024 x 1024.
From the gosu docs:
Caveats:
- subimage only works if the image lives on a single texture. If the image was too large and had to be split up into several OpenGL textures, subimage will return nil (same as #gl_tex_info).
From the source code:
//! Returns the maximum size of an texture that will be allocated
//! internally by Gosu.
//! Useful when extending Gosu using OpenGL.
const unsigned MAX_TEXTURE_SIZE = 1024;