将计算着色器输出渲染到屏幕
Rendering compute-shader output to screen
我正在尝试设置一个管道来进行一些光线渲染。
起初，我设置了一个顶点和一个几何着色器，只采用 1 个任意浮点数，并制作一个四边形，这样我就可以只使用片段着色器，并通过将数据传递给所有着色器或制服来输入数据。
但后来我遇到了计算着色器，并找到了一些教程，但几乎都是一样的，制作四边形并渲染计算着色器输出到它，我认为这很愚蠢，如果你有可能的话使用计算着色器渲染您想要的方式，并仍然通过技巧获得结果。
经过进一步研究，我发现了函数 'glFramebufferImage2D'，据我所知，它将一个 ImageTexture（在我的例子中是我用我的计算着色器写入的那个）附加到帧缓冲区（缓冲区据我所知，这是显示的）。所以我不必做四边形生成技巧。
但是我写的代码只是显示黑屏。
我弄错了什么吗？还是我在代码中遗漏了什么？
这是我的代码：
（我还不担心警告和分离着色器程序。我现在只是想测试一下这个概念。）
main.rs
extern crate sdl2;
extern crate gl;
use sdl2::pixels::Color;
use std::ffi::{CStr, CString};
fn main() {
let width = 512;
let height = 512;
let sdl = sdl2::init().unwrap();
let video_sys = sdl.video().unwrap();
let gl_attr = video_sys.gl_attr();
gl_attr.set_context_profile(sdl2::video::GLProfile::Core);
gl_attr.set_context_version(4, 1);
let window = video_sys.window("test", width, height).opengl().build().unwrap();
let gl_ctx = window.gl_create_context().unwrap();
let gl = gl::load_with(|s| video_sys.gl_get_proc_address(s) as *const std::os::raw::c_void);
unsafe {
gl::Viewport(0, 0, width as gl::types::GLsizei, height as gl::types::GLsizei);
gl::ClearColor(0.0, 0.0, 0.0, 1.0);
}
let shader = unsafe { gl::CreateShader(gl::COMPUTE_SHADER) };
unsafe {
gl::ShaderSource(shader, 1, &CString::new(include_str!("screen.comp")).unwrap().as_ptr(), std::ptr::null());
gl::CompileShader(shader);
}
let program = unsafe { gl::CreateProgram() };
unsafe {
gl::AttachShader(program, shader);
gl::LinkProgram(program);
gl::UseProgram(program);
}
let mut tex_out : gl::types::GLuint = 0;
unsafe {
gl::GenTextures(1, &mut tex_out);
gl::ActiveTexture(gl::TEXTURE0);
gl::BindTexture(gl::TEXTURE_2D, tex_out);
gl::TexImage2D(
gl::TEXTURE_2D,
0,
gl::RGBA32F as gl::types::GLint,
width as gl::types::GLsizei,
height as gl::types::GLsizei,
0,
gl::RGBA,
gl::FLOAT,
std::ptr::null()
);
gl::BindImageTexture(0, tex_out, 0, gl::FALSE, 0, gl::WRITE_ONLY, gl::RGBA32F);
}
let mut event_pump = sdl.event_pump().unwrap();
'main: loop {
for event in event_pump.poll_iter() {
match event {
sdl2::event::Event::Quit {..} => break 'main,
_ => {},
}
}
unsafe {
gl::DispatchCompute(width as gl::types::GLuint, height as gl::types::GLuint, 1);
gl::MemoryBarrier(gl::SHADER_IMAGE_ACCESS_BARRIER_BIT);
gl::FramebufferTexture2D(gl::FRAMEBUFFER, gl::COLOR_ATTACHMENT0, gl::TEXTURE_2D, tex_out, 0);
}
window.gl_swap_window();
}
}
screen.comp
#version 430
layout(local_size_x = 1, local_size_y = 1) in;
layout(rgba32f, binding = 0) uniform image2D img_output;
void main() {
vec4 pixel = vec4(1.0, 1.0, 1.0, 1.0);
ivec2 pixel_coords = ivec2(gl_GlobalInvocationID.xy);
imageStore(img_output, pixel_coords, pixel);
}
编辑：
工作代码：
（试色）
main.rs:
extern crate sdl2;
extern crate gl;
use std::ffi::{CStr, CString};
struct Renderer {
width : u32 ,
height : u32 ,
shader : gl::types::GLuint ,
program : gl::types::GLuint ,
}
impl Renderer {
fn new(width : u32, height : u32, shader_name : &CStr) -> Self {
unsafe {
gl::Viewport(0, 0, width as gl::types::GLsizei, height as gl::types::GLsizei);
gl::ClearColor(0.0, 0.0, 0.0, 1.0);
}
let shader = unsafe { gl::CreateShader(gl::COMPUTE_SHADER) };
unsafe {
gl::ShaderSource(shader, 1, &shader_name.as_ptr(), std::ptr::null());
gl::CompileShader(shader);
}
let program = unsafe { gl::CreateProgram() };
unsafe {
gl::AttachShader(program, shader);
gl::LinkProgram(program);
gl::UseProgram(program);
}
let mut tex_out : gl::types::GLuint = 0;
unsafe {
gl::GenTextures(1, &mut tex_out);
gl::ActiveTexture(gl::TEXTURE0);
gl::BindTexture(gl::TEXTURE_2D, tex_out);
gl::TexParameteri(gl::TEXTURE_2D, gl::TEXTURE_MIN_FILTER, gl::LINEAR as gl::types::GLint);
gl::TexImage2D(
gl::TEXTURE_2D,
0,
gl::RGBA32F as gl::types::GLint,
width as gl::types::GLsizei,
height as gl::types::GLsizei,
0,
gl::RGBA,
gl::FLOAT,
std::ptr::null()
);
gl::BindImageTexture(0, tex_out, 0, gl::FALSE, 0, gl::WRITE_ONLY, gl::RGBA32F);
}
let mut fbo : gl::types::GLuint = 0;
unsafe {
gl::GenFramebuffers(1, &mut fbo );
gl::BindFramebuffer(gl::FRAMEBUFFER, fbo );
gl::FramebufferTexture2D(gl::FRAMEBUFFER, gl::COLOR_ATTACHMENT0, gl::TEXTURE_2D, tex_out, 0);
gl::BindFramebuffer(gl::READ_FRAMEBUFFER, fbo);
gl::BindFramebuffer(gl::DRAW_FRAMEBUFFER, 0);
}
let resolution = unsafe { gl::GetUniformLocation(program, CString::new("iResolution").unwrap().as_ptr()) };
unsafe { gl::Uniform2i(resolution, width as gl::types::GLint, height as gl::types::GLint); }
Self {
width : width ,
height : height ,
shader : shader ,
program : program ,
}
}
fn get_input(&self, name : &str) -> gl::types::GLint {
unsafe { gl::GetUniformLocation(self.program, CString::new(name).unwrap().as_ptr()) }
}
fn input1f(&self, ptr : gl::types::GLint, f : gl::types::GLfloat) {
unsafe { gl::Uniform1f(ptr, f) };
}
fn draw(&self) {
unsafe {
gl::DispatchCompute(self.width as gl::types::GLuint, self.height as gl::types::GLuint, 1);
gl::MemoryBarrier(gl::SHADER_IMAGE_ACCESS_BARRIER_BIT);
gl::BlitFramebuffer(0, 0, self.width as gl::types::GLint, self.height as gl::types::GLint, 0, 0, self.width as gl::types::GLint, self.height as gl::types::GLint, gl::COLOR_BUFFER_BIT, gl::LINEAR);
}
}
}
impl Drop for Renderer {
fn drop(&mut self) {
unsafe {
gl::DeleteShader(self.shader);
gl::DeleteProgram(self.program);
}
}
}
fn main() {
let width = 512;
let height = 512;
let sdl = sdl2::init().unwrap();
let video_sys = sdl.video().unwrap();
let gl_attr = video_sys.gl_attr();
gl_attr.set_context_profile(sdl2::video::GLProfile::Core);
gl_attr.set_context_version(4, 1);
let window = video_sys.window("test", width, height).opengl().build().unwrap();
let _gl_ctx = window.gl_create_context().unwrap();
let _gl = gl::load_with(|s| video_sys.gl_get_proc_address(s) as *const std::os::raw::c_void);
let render = Renderer::new(width, height, &CString::new(include_str!("screen.comp")).unwrap());
let time_attr = render.get_input("time");
let mut event_pump = sdl.event_pump().unwrap();
let mut time = 0.0;
'main: loop {
for event in event_pump.poll_iter() {
match event {
sdl2::event::Event::Quit {..} => break 'main,
_ => {},
}
}
time += 0.01;
if time > 1.0 {
time = 0.0;
}
render.input1f(time_attr, time);
render.draw();
window.gl_swap_window();
}
}
screen.comp:
#version 430
layout(local_size_x = 1, local_size_y = 1) in;
layout(rgba32f, binding = 0) uniform image2D img;
uniform ivec2 iResolution;
uniform float time;
void main() {
ivec2 iCoords = ivec2(gl_GlobalInvocationID.xy);
vec2 uv = vec2(iCoords) / vec2(iResolution);
vec4 pixel = vec4(uv, time, 1.0);
imageStore(img, iCoords, pixel);
}
生成纹理时出现问题。 TEXTURE_MIN_FILTER的初始值为NEAREST_MIPMAP_LINEAR。如果您不更改它并且不创建 mipmap，则纹理不是 "complete".
将 TEXTURE_MIN_FILTER 设置为 NEAREST 或 LINEAR 以解决问题：
gl::BindTexture(gl::TEXTURE_2D, tex_out);
gl::TexParameteri(gl::TEXTURE_2D, gl::TEXTURE_MIN_FILTER, gl::LINEAR)
您已经将图像从计算着色器渲染到纹理对象，但为了将该纹理 blit 到屏幕，您必须将该纹理图像复制到默认帧缓冲区的颜色平面。无法简单地通过附加纹理来更改默认帧缓冲区的颜色平面。
相反，您需要创建一个名为 Framebuffer Object (glGenFramebuffers, glBindFramebuffer) and attach the texture object to the color plane of the framebuffer (glFramebufferTexture2D).
let mut fbo : gl::types::GLuint = 0;
gl::GenFramebuffers(1, &mut fbo);
gl::BindFramebuffer(gl::FRAMEBUFFER, fbo);
gl::FramebufferTexture2D(gl::FRAMEBUFFER, gl::COLOR_ATTACHMENT0, gl::TEXTURE_2D, tex_out, 0)
将此帧缓冲区绑定到目标 GL_READ_FRAMEBUFFER (glBindFramebuffer) 并将默认帧缓冲区（零）绑定到目标 GL_DRAW_FRAMEBUFFER.
gl::BindFramebuffer(gl::READ_FRAMEBUFFER, fbo);
gl::BindFramebuffer(gl::DRAW_FRAMEBUFFER, 0);
最后，在渲染循环中，使用glBlitFramebuffer将命名帧缓冲区对象（纹理）的内容复制到默认帧缓冲区的颜色平面。
gl::DispatchCompute(width as gl::types::GLuint, height as gl::types::GLuint, 1);
gl::MemoryBarrier(gl::SHADER_IMAGE_ACCESS_BARRIER_BIT);
gl::BlitFramebuffer(
0, 0, width as gl::types::GLsizei, height as gl::types::GLsizei,
0, 0, width as gl::types::GLsizei, height as gl::types::GLsizei,
gl::COLOR_BUFFER_BIT, gl::LINEAR);
注意，通过使用glBlitFramebuffer，视口的大小可以与纹理图像的大小不同。
如果纹理的格式是完整的，则此方法将不起作用。它可以工作，因为纹理图像的格式是浮点数，而默认帧缓冲区的格式是定点数。
这是包含建议修复和一些润色的修订版：
extern crate sdl2;
extern crate gl;
//use sdl2::pixels::Color;
//use std::ffi::{CStr, CString};
use std::ffi::{CString};
fn main() {
let width = 512;
let height = 512;
let sdl = sdl2::init().unwrap();
let video_sys = sdl.video().unwrap();
let gl_attr = video_sys.gl_attr();
gl_attr.set_context_profile(sdl2::video::GLProfile::Core);
gl_attr.set_context_version(4, 1);
let window = video_sys.window("test", width, height).opengl().build().unwrap();
let _gl_ctx = window.gl_create_context().unwrap();
let _gl = gl::load_with(|s| video_sys.gl_get_proc_address(s) as *const std::os::raw::c_void);
unsafe {
gl::Viewport(0, 0, width as gl::types::GLsizei, height as gl::types::GLsizei);
gl::ClearColor(0.1, 0.30, 0.50, 1.0);
let shader = gl::CreateShader(gl::COMPUTE_SHADER);
gl::ShaderSource(shader, 1, &CString::new(include_str!("screen.comp")).unwrap().as_ptr(), std::ptr::null());
gl::CompileShader(shader);
let program = gl::CreateProgram();
gl::AttachShader(program, shader);
gl::LinkProgram(program);
gl::UseProgram(program);
let mut tex_out : gl::types::GLuint = 0;
gl::GenTextures(1, &mut tex_out);
gl::ActiveTexture(gl::TEXTURE0);
gl::BindTexture(gl::TEXTURE_2D, tex_out);
gl::TexImage2D( gl::TEXTURE_2D, 0, gl::RGBA32F as gl::types::GLint, width as gl::types::GLsizei, height as gl::types::GLsizei, 0, gl::RGBA, gl::FLOAT, std::ptr::null() );
let mut event_pump = sdl.event_pump().unwrap();
let mut fbo: gl::types::GLuint = 0;
gl::BindImageTexture(0, tex_out, 0, gl::FALSE, 0, gl::WRITE_ONLY, gl::RGBA32F);
gl::GenFramebuffers(1, &mut fbo);
gl::BindFramebuffer(gl::FRAMEBUFFER, fbo);
gl::FramebufferTexture2D(gl::FRAMEBUFFER, gl::COLOR_ATTACHMENT0, gl::TEXTURE_2D, tex_out, 0);
gl::BindFramebuffer(gl::READ_FRAMEBUFFER, fbo);
gl::BindFramebuffer(gl::DRAW_FRAMEBUFFER, 0);
'main: loop {
for event in event_pump.poll_iter() {
match event {
sdl2::event::Event::Quit {..} => break 'main,
_ => {},
}
}
gl::Clear(gl::COLOR_BUFFER_BIT);
gl::DispatchCompute(width as gl::types::GLuint, height as gl::types::GLuint, 1);
gl::MemoryBarrier(gl::SHADER_IMAGE_ACCESS_BARRIER_BIT);
gl::BlitFramebuffer(
0, 0, width as gl::types::GLsizei, height as gl::types::GLsizei,
0, 0, width as gl::types::GLsizei, height as gl::types::GLsizei,
gl::COLOR_BUFFER_BIT, gl::LINEAR);
window.gl_swap_window();
}
}
}
我正在尝试设置一个管道来进行一些光线渲染。
起初，我设置了一个顶点和一个几何着色器，只采用 1 个任意浮点数，并制作一个四边形，这样我就可以只使用片段着色器，并通过将数据传递给所有着色器或制服来输入数据。
但后来我遇到了计算着色器，并找到了一些教程，但几乎都是一样的，制作四边形并渲染计算着色器输出到它，我认为这很愚蠢，如果你有可能的话使用计算着色器渲染您想要的方式，并仍然通过技巧获得结果。
经过进一步研究，我发现了函数 'glFramebufferImage2D'，据我所知，它将一个 ImageTexture（在我的例子中是我用我的计算着色器写入的那个）附加到帧缓冲区（缓冲区据我所知，这是显示的）。所以我不必做四边形生成技巧。 但是我写的代码只是显示黑屏。 我弄错了什么吗？还是我在代码中遗漏了什么？
这是我的代码： （我还不担心警告和分离着色器程序。我现在只是想测试一下这个概念。）
main.rs
extern crate sdl2;
extern crate gl;
use sdl2::pixels::Color;
use std::ffi::{CStr, CString};
fn main() {
let width = 512;
let height = 512;
let sdl = sdl2::init().unwrap();
let video_sys = sdl.video().unwrap();
let gl_attr = video_sys.gl_attr();
gl_attr.set_context_profile(sdl2::video::GLProfile::Core);
gl_attr.set_context_version(4, 1);
let window = video_sys.window("test", width, height).opengl().build().unwrap();
let gl_ctx = window.gl_create_context().unwrap();
let gl = gl::load_with(|s| video_sys.gl_get_proc_address(s) as *const std::os::raw::c_void);
unsafe {
gl::Viewport(0, 0, width as gl::types::GLsizei, height as gl::types::GLsizei);
gl::ClearColor(0.0, 0.0, 0.0, 1.0);
}
let shader = unsafe { gl::CreateShader(gl::COMPUTE_SHADER) };
unsafe {
gl::ShaderSource(shader, 1, &CString::new(include_str!("screen.comp")).unwrap().as_ptr(), std::ptr::null());
gl::CompileShader(shader);
}
let program = unsafe { gl::CreateProgram() };
unsafe {
gl::AttachShader(program, shader);
gl::LinkProgram(program);
gl::UseProgram(program);
}
let mut tex_out : gl::types::GLuint = 0;
unsafe {
gl::GenTextures(1, &mut tex_out);
gl::ActiveTexture(gl::TEXTURE0);
gl::BindTexture(gl::TEXTURE_2D, tex_out);
gl::TexImage2D(
gl::TEXTURE_2D,
0,
gl::RGBA32F as gl::types::GLint,
width as gl::types::GLsizei,
height as gl::types::GLsizei,
0,
gl::RGBA,
gl::FLOAT,
std::ptr::null()
);
gl::BindImageTexture(0, tex_out, 0, gl::FALSE, 0, gl::WRITE_ONLY, gl::RGBA32F);
}
let mut event_pump = sdl.event_pump().unwrap();
'main: loop {
for event in event_pump.poll_iter() {
match event {
sdl2::event::Event::Quit {..} => break 'main,
_ => {},
}
}
unsafe {
gl::DispatchCompute(width as gl::types::GLuint, height as gl::types::GLuint, 1);
gl::MemoryBarrier(gl::SHADER_IMAGE_ACCESS_BARRIER_BIT);
gl::FramebufferTexture2D(gl::FRAMEBUFFER, gl::COLOR_ATTACHMENT0, gl::TEXTURE_2D, tex_out, 0);
}
window.gl_swap_window();
}
}
screen.comp
#version 430
layout(local_size_x = 1, local_size_y = 1) in;
layout(rgba32f, binding = 0) uniform image2D img_output;
void main() {
vec4 pixel = vec4(1.0, 1.0, 1.0, 1.0);
ivec2 pixel_coords = ivec2(gl_GlobalInvocationID.xy);
imageStore(img_output, pixel_coords, pixel);
}
编辑： 工作代码： （试色）
main.rs:
extern crate sdl2;
extern crate gl;
use std::ffi::{CStr, CString};
struct Renderer {
width : u32 ,
height : u32 ,
shader : gl::types::GLuint ,
program : gl::types::GLuint ,
}
impl Renderer {
fn new(width : u32, height : u32, shader_name : &CStr) -> Self {
unsafe {
gl::Viewport(0, 0, width as gl::types::GLsizei, height as gl::types::GLsizei);
gl::ClearColor(0.0, 0.0, 0.0, 1.0);
}
let shader = unsafe { gl::CreateShader(gl::COMPUTE_SHADER) };
unsafe {
gl::ShaderSource(shader, 1, &shader_name.as_ptr(), std::ptr::null());
gl::CompileShader(shader);
}
let program = unsafe { gl::CreateProgram() };
unsafe {
gl::AttachShader(program, shader);
gl::LinkProgram(program);
gl::UseProgram(program);
}
let mut tex_out : gl::types::GLuint = 0;
unsafe {
gl::GenTextures(1, &mut tex_out);
gl::ActiveTexture(gl::TEXTURE0);
gl::BindTexture(gl::TEXTURE_2D, tex_out);
gl::TexParameteri(gl::TEXTURE_2D, gl::TEXTURE_MIN_FILTER, gl::LINEAR as gl::types::GLint);
gl::TexImage2D(
gl::TEXTURE_2D,
0,
gl::RGBA32F as gl::types::GLint,
width as gl::types::GLsizei,
height as gl::types::GLsizei,
0,
gl::RGBA,
gl::FLOAT,
std::ptr::null()
);
gl::BindImageTexture(0, tex_out, 0, gl::FALSE, 0, gl::WRITE_ONLY, gl::RGBA32F);
}
let mut fbo : gl::types::GLuint = 0;
unsafe {
gl::GenFramebuffers(1, &mut fbo );
gl::BindFramebuffer(gl::FRAMEBUFFER, fbo );
gl::FramebufferTexture2D(gl::FRAMEBUFFER, gl::COLOR_ATTACHMENT0, gl::TEXTURE_2D, tex_out, 0);
gl::BindFramebuffer(gl::READ_FRAMEBUFFER, fbo);
gl::BindFramebuffer(gl::DRAW_FRAMEBUFFER, 0);
}
let resolution = unsafe { gl::GetUniformLocation(program, CString::new("iResolution").unwrap().as_ptr()) };
unsafe { gl::Uniform2i(resolution, width as gl::types::GLint, height as gl::types::GLint); }
Self {
width : width ,
height : height ,
shader : shader ,
program : program ,
}
}
fn get_input(&self, name : &str) -> gl::types::GLint {
unsafe { gl::GetUniformLocation(self.program, CString::new(name).unwrap().as_ptr()) }
}
fn input1f(&self, ptr : gl::types::GLint, f : gl::types::GLfloat) {
unsafe { gl::Uniform1f(ptr, f) };
}
fn draw(&self) {
unsafe {
gl::DispatchCompute(self.width as gl::types::GLuint, self.height as gl::types::GLuint, 1);
gl::MemoryBarrier(gl::SHADER_IMAGE_ACCESS_BARRIER_BIT);
gl::BlitFramebuffer(0, 0, self.width as gl::types::GLint, self.height as gl::types::GLint, 0, 0, self.width as gl::types::GLint, self.height as gl::types::GLint, gl::COLOR_BUFFER_BIT, gl::LINEAR);
}
}
}
impl Drop for Renderer {
fn drop(&mut self) {
unsafe {
gl::DeleteShader(self.shader);
gl::DeleteProgram(self.program);
}
}
}
fn main() {
let width = 512;
let height = 512;
let sdl = sdl2::init().unwrap();
let video_sys = sdl.video().unwrap();
let gl_attr = video_sys.gl_attr();
gl_attr.set_context_profile(sdl2::video::GLProfile::Core);
gl_attr.set_context_version(4, 1);
let window = video_sys.window("test", width, height).opengl().build().unwrap();
let _gl_ctx = window.gl_create_context().unwrap();
let _gl = gl::load_with(|s| video_sys.gl_get_proc_address(s) as *const std::os::raw::c_void);
let render = Renderer::new(width, height, &CString::new(include_str!("screen.comp")).unwrap());
let time_attr = render.get_input("time");
let mut event_pump = sdl.event_pump().unwrap();
let mut time = 0.0;
'main: loop {
for event in event_pump.poll_iter() {
match event {
sdl2::event::Event::Quit {..} => break 'main,
_ => {},
}
}
time += 0.01;
if time > 1.0 {
time = 0.0;
}
render.input1f(time_attr, time);
render.draw();
window.gl_swap_window();
}
}
screen.comp:
#version 430
layout(local_size_x = 1, local_size_y = 1) in;
layout(rgba32f, binding = 0) uniform image2D img;
uniform ivec2 iResolution;
uniform float time;
void main() {
ivec2 iCoords = ivec2(gl_GlobalInvocationID.xy);
vec2 uv = vec2(iCoords) / vec2(iResolution);
vec4 pixel = vec4(uv, time, 1.0);
imageStore(img, iCoords, pixel);
}
生成纹理时出现问题。 TEXTURE_MIN_FILTER的初始值为NEAREST_MIPMAP_LINEAR。如果您不更改它并且不创建 mipmap，则纹理不是 "complete".
将 TEXTURE_MIN_FILTER 设置为 NEAREST 或 LINEAR 以解决问题：
gl::BindTexture(gl::TEXTURE_2D, tex_out);
gl::TexParameteri(gl::TEXTURE_2D, gl::TEXTURE_MIN_FILTER, gl::LINEAR)
您已经将图像从计算着色器渲染到纹理对象，但为了将该纹理 blit 到屏幕，您必须将该纹理图像复制到默认帧缓冲区的颜色平面。无法简单地通过附加纹理来更改默认帧缓冲区的颜色平面。
相反，您需要创建一个名为 Framebuffer Object (glGenFramebuffers, glBindFramebuffer) and attach the texture object to the color plane of the framebuffer (glFramebufferTexture2D).
let mut fbo : gl::types::GLuint = 0;
gl::GenFramebuffers(1, &mut fbo);
gl::BindFramebuffer(gl::FRAMEBUFFER, fbo);
gl::FramebufferTexture2D(gl::FRAMEBUFFER, gl::COLOR_ATTACHMENT0, gl::TEXTURE_2D, tex_out, 0)
将此帧缓冲区绑定到目标 GL_READ_FRAMEBUFFER (glBindFramebuffer) 并将默认帧缓冲区（零）绑定到目标 GL_DRAW_FRAMEBUFFER.
gl::BindFramebuffer(gl::READ_FRAMEBUFFER, fbo);
gl::BindFramebuffer(gl::DRAW_FRAMEBUFFER, 0);
最后，在渲染循环中，使用glBlitFramebuffer将命名帧缓冲区对象（纹理）的内容复制到默认帧缓冲区的颜色平面。
gl::DispatchCompute(width as gl::types::GLuint, height as gl::types::GLuint, 1);
gl::MemoryBarrier(gl::SHADER_IMAGE_ACCESS_BARRIER_BIT);
gl::BlitFramebuffer(
0, 0, width as gl::types::GLsizei, height as gl::types::GLsizei,
0, 0, width as gl::types::GLsizei, height as gl::types::GLsizei,
gl::COLOR_BUFFER_BIT, gl::LINEAR);
注意，通过使用glBlitFramebuffer，视口的大小可以与纹理图像的大小不同。
如果纹理的格式是完整的，则此方法将不起作用。它可以工作，因为纹理图像的格式是浮点数，而默认帧缓冲区的格式是定点数。
这是包含建议修复和一些润色的修订版：
extern crate sdl2;
extern crate gl;
//use sdl2::pixels::Color;
//use std::ffi::{CStr, CString};
use std::ffi::{CString};
fn main() {
let width = 512;
let height = 512;
let sdl = sdl2::init().unwrap();
let video_sys = sdl.video().unwrap();
let gl_attr = video_sys.gl_attr();
gl_attr.set_context_profile(sdl2::video::GLProfile::Core);
gl_attr.set_context_version(4, 1);
let window = video_sys.window("test", width, height).opengl().build().unwrap();
let _gl_ctx = window.gl_create_context().unwrap();
let _gl = gl::load_with(|s| video_sys.gl_get_proc_address(s) as *const std::os::raw::c_void);
unsafe {
gl::Viewport(0, 0, width as gl::types::GLsizei, height as gl::types::GLsizei);
gl::ClearColor(0.1, 0.30, 0.50, 1.0);
let shader = gl::CreateShader(gl::COMPUTE_SHADER);
gl::ShaderSource(shader, 1, &CString::new(include_str!("screen.comp")).unwrap().as_ptr(), std::ptr::null());
gl::CompileShader(shader);
let program = gl::CreateProgram();
gl::AttachShader(program, shader);
gl::LinkProgram(program);
gl::UseProgram(program);
let mut tex_out : gl::types::GLuint = 0;
gl::GenTextures(1, &mut tex_out);
gl::ActiveTexture(gl::TEXTURE0);
gl::BindTexture(gl::TEXTURE_2D, tex_out);
gl::TexImage2D( gl::TEXTURE_2D, 0, gl::RGBA32F as gl::types::GLint, width as gl::types::GLsizei, height as gl::types::GLsizei, 0, gl::RGBA, gl::FLOAT, std::ptr::null() );
let mut event_pump = sdl.event_pump().unwrap();
let mut fbo: gl::types::GLuint = 0;
gl::BindImageTexture(0, tex_out, 0, gl::FALSE, 0, gl::WRITE_ONLY, gl::RGBA32F);
gl::GenFramebuffers(1, &mut fbo);
gl::BindFramebuffer(gl::FRAMEBUFFER, fbo);
gl::FramebufferTexture2D(gl::FRAMEBUFFER, gl::COLOR_ATTACHMENT0, gl::TEXTURE_2D, tex_out, 0);
gl::BindFramebuffer(gl::READ_FRAMEBUFFER, fbo);
gl::BindFramebuffer(gl::DRAW_FRAMEBUFFER, 0);
'main: loop {
for event in event_pump.poll_iter() {
match event {
sdl2::event::Event::Quit {..} => break 'main,
_ => {},
}
}
gl::Clear(gl::COLOR_BUFFER_BIT);
gl::DispatchCompute(width as gl::types::GLuint, height as gl::types::GLuint, 1);
gl::MemoryBarrier(gl::SHADER_IMAGE_ACCESS_BARRIER_BIT);
gl::BlitFramebuffer(
0, 0, width as gl::types::GLsizei, height as gl::types::GLsizei,
0, 0, width as gl::types::GLsizei, height as gl::types::GLsizei,
gl::COLOR_BUFFER_BIT, gl::LINEAR);
window.gl_swap_window();
}
}
}