Struct Painter

pub struct Painter { /* private fields */ }

An OpenGL painter using glow.

This is responsible for painting egui and managing egui textures. You can access the underlying glow::Context with Self::gl.

This struct must be destroyed with Painter::destroy before dropping, to ensure OpenGL objects have been properly deleted and are not leaked.

NOTE: all egui viewports share the same painter.

Implementations

impl Painter

pub fn new( gl: Arc<Context>, shader_prefix: &str, shader_version: Option<ShaderVersion>, dithering: bool, ) -> Result<Self, PainterError>

Create painter.

Set pp_fb_extent to the framebuffer size to enable sRGB support on OpenGL ES and WebGL.

Set shader_prefix if you want to turn on shader workaround e.g. "#define APPLY_BRIGHTENING_GAMMA\n" (see https://github.com/emilk/egui/issues/794).

Errors

will return Err below cases

• failed to compile shader
• failed to create postprocess on webgl with sRGB support
• failed to create buffer

pub fn gl(&self) -> &Arc<Context>

Access the shared glow context.

pub fn max_texture_side(&self) -> usize

pub fn intermediate_fbo(&self) -> Option<Framebuffer>

The framebuffer we use as an intermediate render target, or None if we are painting to the screen framebuffer directly.

This is the framebuffer that is bound when egui::Shape::Callback is called, and is where any callbacks should ultimately render onto.

So if in a egui::Shape::Callback you need to use an offscreen FBO, you should then restore to this afterwards with gl.bind_framebuffer(glow::FRAMEBUFFER, painter.intermediate_fbo());

pub fn clear(&self, screen_size_in_pixels: [u32; 2], clear_color: [f32; 4])

pub fn paint_and_update_textures( &mut self, screen_size_px: [u32; 2], pixels_per_point: f32, clipped_primitives: &[ClippedPrimitive], textures_delta: &TexturesDelta, )

You are expected to have cleared the color buffer before calling this.

pub fn paint_primitives( &mut self, screen_size_px: [u32; 2], pixels_per_point: f32, clipped_primitives: &[ClippedPrimitive], )

Main entry-point for painting a frame.

You should call target.clear_color(..) before and target.finish() after this.

The following OpenGL features will be set:

• Scissor test will be enabled
• Cull face will be disabled
• Blend will be enabled

The scissor area and blend parameters will be changed.

As well as this, the following objects will be unset:

• Vertex Buffer
• Element Buffer
• Texture (and active texture will be set to 0)
• Program

Please be mindful of these effects when integrating into your program, and also be mindful of the effects your program might have on this code. Look at the source if in doubt.

pub fn set_texture(&mut self, tex_id: TextureId, delta: &ImageDelta)

pub fn free_texture(&mut self, tex_id: TextureId)

pub fn texture(&self, texture_id: TextureId) -> Option<Texture>

Get the glow::Texture bound to a egui::TextureId.

pub fn register_native_texture(&mut self, native: Texture) -> TextureId

pub fn replace_native_texture(&mut self, id: TextureId, replacing: Texture)

pub fn read_screen_rgba(&self, [w, h]: [u32; 2]) -> ColorImage

pub fn read_screen_rgb(&self, [w, h]: [u32; 2]) -> Vec<u8>

pub fn destroy(&mut self)

This function must be called before Painter is dropped, as Painter has some OpenGL objects that should be deleted.

Trait Implementations

impl Drop for Painter

fn drop(&mut self)

Executes the destructor for this type.