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use crate::*;
/// A framebuffer that allows render-to-texture
pub struct Surface {
pub(crate) ctx: Context,
pub(crate) id: GlFramebuffer,
pub(crate) texture: Option<Texture>,
}
impl Surface {
/// Create a new Surface to render to, backed by the given texture
pub fn new(ctx: &Context, texture: Texture) -> Result<Surface, GolemError> {
let ctx = Context(ctx.0.clone());
let gl = &ctx.0.gl;
let id = unsafe { gl.create_framebuffer() }?;
unsafe {
gl.bind_framebuffer(glow::FRAMEBUFFER, Some(id));
gl.framebuffer_texture_2d(
glow::FRAMEBUFFER,
glow::COLOR_ATTACHMENT0,
glow::TEXTURE_2D,
Some(texture.id),
0,
);
gl.bind_framebuffer(glow::FRAMEBUFFER, *ctx.0.current_surface.borrow());
}
Ok(Surface {
ctx,
id,
texture: Some(texture),
})
}
/// Check if a texture is attached to this Surface
///
/// Textures can be attached via [`Surface::put_texture`] and removed via
/// [`Surface::take_texture`].
pub fn has_texture(&self) -> bool {
self.texture.is_some()
}
/// Check if this surface is bound to be operated on
///
/// Call [`Surface::bind`] to bind the surface, which is required to render to it or to call
/// [`Surface::get_pixel_data`]
pub fn is_bound(&self) -> bool {
match *self.ctx.0.current_surface.borrow() {
Some(surface) => self.id == surface,
None => false,
}
}
/// Remove the texture from the Surface to operate on it
///
/// Until another texture is added via [`Surface::put_texture`], operations on the Surface will
/// panic.
pub fn take_texture(&mut self) -> Option<Texture> {
let gl = &self.ctx.0.gl;
unsafe {
gl.framebuffer_texture_2d(
glow::FRAMEBUFFER,
glow::COLOR_ATTACHMENT0,
glow::TEXTURE_2D,
None,
0,
);
}
self.texture.take()
}
/// Put a texture into the Surface to operate on
pub fn put_texture(&mut self, texture: Texture) {
let gl = &self.ctx.0.gl;
unsafe {
gl.framebuffer_texture_2d(
glow::FRAMEBUFFER,
glow::COLOR_ATTACHMENT0,
glow::TEXTURE_2D,
Some(texture.id),
0,
);
}
self.texture = Some(texture);
}
/// Borrow the texture the Surface is holding
///
/// # Safety
///
/// The texture can be used and referenced while it is bound and while it is not bound.
/// However, it is undefined behavior to form a 'texture loop.' If a Surface is actively bound,
/// the texture cannot be used in the rendering pipeline. It is important to only ever render
/// to the Surface *or* use its texture, not both.
pub unsafe fn borrow_texture(&self) -> Option<&Texture> {
self.texture.as_ref()
}
/// Set the current render target to this surface
///
/// Also necessary for operations like [`Surface::get_pixel_data`]
pub fn bind(&self) {
assert!(
self.has_texture(),
"The surface had no attached image when bind was called"
);
*self.ctx.0.current_surface.borrow_mut() = Some(self.id);
let gl = &self.ctx.0.gl;
unsafe {
gl.bind_framebuffer(glow::FRAMEBUFFER, Some(self.id));
}
}
/// Unbind the surface and set the render target to the screen
pub fn unbind(ctx: &Context) {
*ctx.0.current_surface.borrow_mut() = None;
let gl = &ctx.0.gl;
unsafe {
gl.bind_framebuffer(glow::FRAMEBUFFER, None);
}
}
/// Get the pixel data and write it to a buffer
///
/// The surface must be bound first, see [`Surface::bind`].
///
/// The ColorFormat determines how many bytes each pixel is: 3 bytes for RGB and 4 for RGBA. The
/// slice needs have a length of `(width - x) * (height - y) * ColorFormat size`.
pub fn get_pixel_data(
&self,
x: u32,
y: u32,
width: u32,
height: u32,
format: ColorFormat,
data: &mut [u8],
) {
assert!(
self.is_bound(),
"The surface wasn't bound when get_pixel_data was called"
);
assert!(
self.has_texture(),
"The surface had no attached image when get_pixel_data was called"
);
let bytes_per_pixel = format.bytes_per_pixel();
let length = (width * height * bytes_per_pixel) as usize;
assert!(
data.len() >= length,
"The buffer was not large enough to hold the data"
);
let format = format.gl_format();
let gl = &self.ctx.0.gl;
unsafe {
gl.bind_framebuffer(glow::FRAMEBUFFER, Some(self.id));
gl.read_pixels(
x as i32,
y as i32,
width as i32,
height as i32,
format,
glow::UNSIGNED_BYTE,
data,
);
gl.bind_framebuffer(glow::FRAMEBUFFER, None);
}
}
/// Get the width of the inner texture, or None if there is no texture
pub fn width(&self) -> Option<u32> {
self.texture.as_ref().map(|tex| tex.width())
}
/// Get the height of the inner texture, or None if there is no texture
pub fn height(&self) -> Option<u32> {
self.texture.as_ref().map(|tex| tex.height())
}
}
impl Drop for Surface {
fn drop(&mut self) {
unsafe {
self.ctx.0.gl.delete_framebuffer(self.id);
}
}
}