考虑两个程序，以及它们之间的区别：
$ diff flashes/src/main.rs doesnt_flash/src/main.rs
22,23c22
<
< let mut i = 0;
---
> let mut cursor_poses: Vec<(f64, f64)> = Vec::new();
28c27
< mx = x; my = y;
---
> cursor_poses.push((x,y));
32,33c31,33
< if i == 0 {
< graphics::clear([1.0; 4], g);
---
> graphics::clear([1.0; 4], g);
> for &(x, y) in cursor_poses.iter() {
> draw_cursor_pos([x, y], &c, g);
35,36d34
< draw_cursor_pos([mx, my], &c, g);
< i+=1;
该程序是一个非常基础的绘画程序，只有一个画笔宽度，画笔笔触颜色，画布大小，不保存等；哦，要停止绘图，请将鼠标移出窗口，因为每次越过窗口时，这都算作绘图；-)
flashes.rse.render_args()除了第一次之外，每次都不会绘制每个像素。doesnt_flash.rs每次e.render_args()达到时都会绘制每个像素。这是两个程序之间的唯一区别。
虽然在这个程序中生成内容并不需要很长时间，所以当鼠标在窗口上移动时重新生成数百次是可以接受的，这似乎效率低下。理论上，随着越来越多的点被添加到屏幕上，每次迭代gl.draw需要的时间越来越长。在实践中，调用graphics::ellipse一次与一万次之间的差异在现代硬件上并不显着。
我想写的其他程序没有那么奢侈，因为生成结果并放在屏幕上需要更长的时间。
在仔细阅读 API 时，我没有想出明显的方法来“什么都不做”。我假设我必须将屏幕更改写入某个缓冲区对象，然后在调用GlGraphics时反馈此缓冲区对象，e.render_args()但我不需要更新屏幕。
问题是，我似乎找不到这个缓冲区对象。:-(
我怎样才能“什么都不做”而不让屏幕闪烁？如果我的理论是正确的，我怎样才能绘制到GlGraphics缓冲区而不是屏幕，然后当我没有任何新东西要绘制时将缓冲区反馈回屏幕？
货运.toml
[package]
name = "stackoverflow-piston-example"
version = "0.0.0"
authors = ["Fred"]
description = "Note: This program can be used for both of the programs below. Simply use `cargo new` and save either of the below files as `src/main.rs`"
keywords = []
[dependencies]
piston = "0.35.0"
piston2d-opengl_graphics = "0.50.0"
piston2d-graphics = "0.24.0"
piston2d-touch_visualizer = "0.8.0"
pistoncore-sdl2_window = "0.47.0"
dont_flash.rs
extern crate piston;
extern crate opengl_graphics;
extern crate graphics;
extern crate touch_visualizer;
extern crate sdl2_window;
use opengl_graphics::{ GlGraphics, OpenGL };
use graphics::{ Context, Graphics };
use piston::input::*;
use piston::event_loop::*;
use sdl2_window::Sdl2Window as AppWindow;
static CURSOR_POS_COLOR: [f32; 4] = [0.0, 0.0, 0.0, 1.0];
fn main() {
let opengl = OpenGL::V3_2;
let mut window: AppWindow = piston::window::WindowSettings::new("Example for StackOverflow", [600, 600])
.exit_on_esc(true).opengl(opengl).build().unwrap();
let ref mut gl = GlGraphics::new(opengl);
let (mut mx, mut my) = (0., 0.);
let mut cursor_poses: Vec<(f64, f64)> = Vec::new();
let mut events = Events::new(EventSettings::new().lazy(true));
while let Some(e) = events.next(&mut window) {
e.mouse_cursor(|x, y| {
cursor_poses.push((x,y));
});
if let Some(args) = e.render_args() {
gl.draw(args.viewport(), |c, g| {
graphics::clear([1.0; 4], g);
for &(x, y) in cursor_poses.iter() {
draw_cursor_pos([x, y], &c, g);
}
}
);
}
}
}
fn draw_cursor_pos<G: Graphics>(
cursor: [f64; 2],
c: &Context,
g: &mut G,
) {
graphics::ellipse(
CURSOR_POS_COLOR,
graphics::ellipse::circle(cursor[0], cursor[1], 4.0),
c.transform,
g
);
}
闪光灯.rs
extern crate piston;
extern crate opengl_graphics;
extern crate graphics;
extern crate touch_visualizer;
extern crate sdl2_window;
use opengl_graphics::{ GlGraphics, OpenGL };
use graphics::{ Context, Graphics };
use piston::input::*;
use piston::event_loop::*;
use sdl2_window::Sdl2Window as AppWindow;
static CURSOR_POS_COLOR: [f32; 4] = [0.0, 0.0, 0.0, 1.0];
fn main() {
let opengl = OpenGL::V3_2;
let mut window: AppWindow = piston::window::WindowSettings::new("Example for StackOverflow", [600, 600])
.exit_on_esc(true).opengl(opengl).build().unwrap();
let ref mut gl = GlGraphics::new(opengl);
let (mut mx, mut my) = (0., 0.);
let mut i = 0;
let mut events = Events::new(EventSettings::new().lazy(true));
while let Some(e) = events.next(&mut window) {
e.mouse_cursor(|x, y| {
mx = x; my = y;
});
if let Some(args) = e.render_args() {
gl.draw(args.viewport(), |c, g| {
if i == 0 {
graphics::clear([1.0; 4], g);
}
draw_cursor_pos([mx, my], &c, g);
i+=1;
}
);
}
}
}
fn draw_cursor_pos<G: Graphics>(
cursor: [f64; 2],
c: &Context,
g: &mut G,
) {
graphics::ellipse(
CURSOR_POS_COLOR,
graphics::ellipse::circle(cursor[0], cursor[1], 4.0),
c.transform,
g
);
}