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use DrawState; use types::{self, Matrix2d, Scalar}; use {CircleArc, Ellipse, Image, ImageSize, Line, Polygon, Rectangle}; /// Implemented by all graphics back-ends. /// /// [An example back-end using raw OpenGL](https://github.com/PistonDevelopers/opengl_graphics) /// /// By default, this design uses triangles as graphics primitives. /// This is supported by all GPUs and easy to implement in shader languages. /// /// Default trait methods can be overridden for better performance or higher /// quality. /// /// When drawing, use this trait as generic constraint: /// /// ``` /// use graphics::{Graphics, Context}; /// /// fn draw<G: Graphics>(c: &Context, g: &mut G) { /// //... /// } /// ``` /// /// Color space is sRGB. /// /// ### Notice for back-end authors /// /// When sRGB is enabled for a back-end shader, the gamma must be converted /// to linear space when used as vertex color or uniform parameter. /// To convert gamma, use `color::gamma_srgb_to_linear`. /// /// For more information, see /// https://github.com/PistonDevelopers/piston/issues/1014. pub trait Graphics: Sized { /// The texture type associated with the back-end. /// /// In generic code, this type is often unknown. /// This might lead to more boilerplate code: /// /// ``` /// use graphics::{Graphics, Context, ImageSize}; /// /// fn draw_texture<G, T>(c: &Context, g: &mut G) /// where G: Graphics<Texture = T>, T: ImageSize { /// //... /// } /// ``` /// /// Code written specifically for one back-end can be easier to write. /// Later, when the code is done, it can be refactored into generic code. type Texture: ImageSize; /// Clears background with a color. /// /// The color should replace the values in the buffer. /// /// Color space is sRGB. fn clear_color(&mut self, color: types::Color); /// Clears stencil buffer with a value, usually 0. /// /// A stencil buffer contains values that are not visible on the screen. /// These values are used to test against the pixel to paint. /// /// If you are drawing a shape for clipping and forgot to clear the /// stencil buffer, then the clipping shape will carry over in next frame /// and cause artifacts. fn clear_stencil(&mut self, value: u8); /// Renders list of 2d triangles using a solid color. /// /// All vertices share the same color. /// /// The back-end calls the closure with a closure to receive vertices. /// First, the back-end sets up shaders and such to prepare. /// Then it calls the closure, which calls back with chunks of vertices. /// The number of vertices per chunk never exceeds /// `BACK_END_MAX_VERTEX_COUNT`. /// Vertex positions are encoded `[[x0, y0], [x1, y1], ...]`. /// /// Color space is sRGB. fn tri_list<F>(&mut self, draw_state: &DrawState, color: &[f32; 4], f: F) where F: FnMut(&mut dyn FnMut(&[[f32; 2]])); /// Same as `tri_list`, but with individual vertex colors. /// /// Argument are `|vertices: &[[f32; 2], colors: &[[f32; 4]]]|`. fn tri_list_c<F>(&mut self, draw_state: &DrawState, f: F) where F: FnMut(&mut dyn FnMut(&[[f32; 2]], &[[f32; 4]])); /// Renders list of 2d triangles using a color and a texture. /// /// All vertices share the same color. /// /// Tip: For objects of different colors, use grayscale textures. /// The texture color gets multiplied with the color. /// /// A texture coordinate is assigned per vertex (from [0, 0] to [1, 1]). /// /// The back-end calls the closure with a closure to receive vertices. /// First, the back-end sets up shaders and such to prepare. /// Then it calls the closure, which calls back with chunks of vertices. /// The number of vertices per chunk never exceeds /// `BACK_END_MAX_VERTEX_COUNT`. /// Vertex positions are encoded `[[x0, y0], [x1, y1], ...]`. /// Texture coordinates are encoded `[[u0, v0], [u1, v1], ...]`. /// /// Chunks uses separate buffer for vertex positions and texture coordinates. /// Arguments are `|vertices: &[[f32; 2]], texture_coords: &[[f32; 2]]|`. /// /// Color space is sRGB. fn tri_list_uv<F>(&mut self, draw_state: &DrawState, color: &[f32; 4], texture: &<Self as Graphics>::Texture, f: F) where F: FnMut(&mut dyn FnMut(&[[f32; 2]], &[[f32; 2]])); /// Same as `tri_list_uv`, but with individual vertex colors. /// /// Argument are `|vertices: &[[f32; 2], texture_coors: &[[f32; 2]], colors: &[[f32; 4]]]|`. fn tri_list_uv_c<F>(&mut self, draw_state: &DrawState, texture: &<Self as Graphics>::Texture, f: F) where F: FnMut(&mut dyn FnMut(&[[f32; 2]], &[[f32; 2]], &[[f32; 4]])); /// Draws a rectangle. /// /// Can be overriden in the back-end for higher performance. /// /// Instead of calling this directly, use `Rectangle::draw`. #[inline(always)] fn rectangle<R: Into<types::Rectangle>>(&mut self, r: &Rectangle, rectangle: R, draw_state: &DrawState, transform: Matrix2d) { r.draw_tri(rectangle, draw_state, transform, self); } /// Draws a polygon. /// /// Can be overridden in the back-end for higher performance. /// /// Instead of calling this directly, use `Polygon::draw`. #[inline(always)] fn polygon(&mut self, p: &Polygon, polygon: types::Polygon, draw_state: &DrawState, transform: Matrix2d) { p.draw_tri(polygon, draw_state, transform, self); } /// Draws a tweened polygon using linear interpolation. /// /// Can be overridden in the back-end for higher performance. /// /// Instead of calling this directly, use `Polygon::draw_tween_lerp`. #[inline(always)] fn polygon_tween_lerp(&mut self, p: &Polygon, polygons: types::Polygons, tween_factor: Scalar, draw_state: &DrawState, transform: Matrix2d) { p.draw_tween_lerp_tri(polygons, tween_factor, draw_state, transform, self); } /// Draws image. /// /// Can be overridden in the back-end for higher performance. /// /// Instead of calling this directly, use `Image::draw`. #[inline(always)] fn image(&mut self, image: &Image, texture: &Self::Texture, draw_state: &DrawState, transform: Matrix2d) { image.draw_tri(texture, draw_state, transform, self); } /// Draws ellipse. /// /// Can be overridden in the back-end for higher performance. /// /// Instead of calling this directly, use `Ellipse::draw`. #[inline(always)] fn ellipse<R: Into<types::Rectangle>>(&mut self, e: &Ellipse, rectangle: R, draw_state: &DrawState, transform: Matrix2d) { e.draw_tri(rectangle, draw_state, transform, self); } /// Draws line. /// /// Can be overridden in the back-end for higher performance. /// /// Instead of calling this directly, use `Line::draw`. #[inline(always)] fn line<L: Into<types::Line>>(&mut self, l: &Line, line: L, draw_state: &DrawState, transform: Matrix2d) { l.draw_tri(line, draw_state, transform, self); } /// Draws circle arc. /// /// Can be overriden in the back-end for higher performance. /// /// Instead of calling this directly, use `CircleArc::draw`. #[inline(always)] fn circle_arc<R: Into<types::Rectangle>>(&mut self, c: &CircleArc, rectangle: R, draw_state: &DrawState, transform: Matrix2d) { c.draw_tri(rectangle, draw_state, transform, self); } }