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@simias
Created Feb 9, 2015
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Example program for gl-rs + rust-sdl2
// Copyright 2013 The gl-rs developers. For a full listing of the authors,
// refer to the AUTHORS file at the top-level directory of this distribution.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
extern crate gl;
extern crate sdl2;
extern crate libc;
use std::ffi::CString;
use std::ptr;
use std::str;
use std::mem;
use libc::c_void;
use gl::types::{GLfloat, GLenum, GLuint, GLint, GLchar, GLsizeiptr};
use gl::types::{GLboolean};
use sdl2::video::{Window, GLAttr, OPENGL, WindowPos};
use sdl2::event::Event;
use sdl2::keycode::KeyCode;
fn main() {
sdl2::init(::sdl2::INIT_VIDEO);
sdl2::video::gl_set_attribute(GLAttr::GLContextMajorVersion, 3);
sdl2::video::gl_set_attribute(GLAttr::GLContextMinorVersion, 2);
sdl2::video::gl_set_attribute(GLAttr::GLDoubleBuffer, 1);
sdl2::video::gl_set_attribute(GLAttr::GLDepthSize, 24);
let window = match Window::new("gb-rs",
WindowPos::PosCentered,
WindowPos::PosCentered,
800, 600,
OPENGL) {
Ok(window) => window,
Err(err) => panic!("failed to create SDL2 window: {}", err)
};
let context = window.gl_create_context().unwrap();
gl::load_with(|s| sdl2::video::gl_get_proc_address(s).unwrap() as *const c_void);
sdl2::video::gl_set_swap_interval(1);
let vs = compile_shader(VS_SRC, gl::VERTEX_SHADER);
let fs = compile_shader(FS_SRC, gl::FRAGMENT_SHADER);
let program = link_program(vs, fs);
let mut vao = 0;
let mut vbo = 0;
unsafe {
// Create Vertex Array Object
gl::GenVertexArrays(1, &mut vao);
gl::BindVertexArray(vao);
// Create a Vertex Buffer Object and copy the vertex data to it
gl::GenBuffers(1, &mut vbo);
gl::BindBuffer(gl::ARRAY_BUFFER, vbo);
gl::BufferData(gl::ARRAY_BUFFER,
(VERTEX_DATA.len() * mem::size_of::<GLfloat>()) as GLsizeiptr,
mem::transmute(&VERTEX_DATA[0]),
gl::STATIC_DRAW);
// Use shader program
gl::UseProgram(program);
gl::BindFragDataLocation(program, 0,
CString::from_slice(b"out_color").as_ptr());
// Specify the layout of the vertex data
let pos_attr = gl::GetAttribLocation(program,
CString::from_slice(b"position").as_ptr());
gl::EnableVertexAttribArray(pos_attr as GLuint);
gl::VertexAttribPointer(pos_attr as GLuint, 2, gl::FLOAT,
gl::FALSE as GLboolean, 0, ptr::null());
}
'mainloop: loop {
loop {
match sdl2::event::poll_event() {
Event::None => break,
Event::KeyDown { keycode: KeyCode::Escape, .. } => break 'mainloop,
Event::Quit { .. } => break 'mainloop,
_ => (),
}
}
unsafe {
// Clear the screen to black
gl::ClearColor(0.3, 0.3, 0.3, 1.0);
gl::Clear(gl::COLOR_BUFFER_BIT);
// Draw a triangle from the 3 vertices
gl::DrawArrays(gl::TRIANGLES, 0, 3);
}
window.gl_swap_window();
}
sdl2::quit();
}
// Vertex data
static VERTEX_DATA: [GLfloat; 6] = [
0.0, 0.5,
0.5, -0.5,
-0.5, -0.5
];
// Shader sources
static VS_SRC: &'static str =
"#version 150\n\
in vec2 position;\n\
void main() {\n\
gl_Position = vec4(position, 0.0, 1.0);\n\
}";
static FS_SRC: &'static str =
"#version 150\n\
out vec4 out_color;\n\
void main() {\n\
out_color = vec4(1.0, 1.0, 1.0, 1.0);\n\
}";
fn compile_shader(src: &str, ty: GLenum) -> GLuint {
let shader;
unsafe {
shader = gl::CreateShader(ty);
// Attempt to compile the shader
let c_str = CString::from_slice(src.as_bytes());
gl::ShaderSource(shader, 1, &c_str.as_ptr(), ptr::null());
gl::CompileShader(shader);
// Get the compile status
let mut status = gl::FALSE as GLint;
gl::GetShaderiv(shader, gl::COMPILE_STATUS, &mut status);
// Fail on error
if status != (gl::TRUE as GLint) {
let mut len = 0;
gl::GetShaderiv(shader, gl::INFO_LOG_LENGTH, &mut len);
let mut buf = Vec::new();
buf.set_len((len as usize) - 1); // subtract 1 to skip the trailing null character
gl::GetShaderInfoLog(shader, len, ptr::null_mut(), buf.as_mut_ptr() as *mut GLchar);
panic!("{}", str::from_utf8(buf.as_slice()).ok().expect("ShaderInfoLog not valid utf8"));
}
}
shader
}
fn link_program(vs: GLuint, fs: GLuint) -> GLuint {
unsafe {
let program = gl::CreateProgram();
gl::AttachShader(program, vs);
gl::AttachShader(program, fs);
gl::LinkProgram(program);
// Get the link status
let mut status = gl::FALSE as GLint;
gl::GetProgramiv(program, gl::LINK_STATUS, &mut status);
// Fail on error
if status != (gl::TRUE as GLint) {
let mut len: GLint = 0;
gl::GetProgramiv(program, gl::INFO_LOG_LENGTH, &mut len);
let mut buf = Vec::new();
buf.set_len((len as usize) - 1); // subtract 1 to skip the trailing null character
gl::GetProgramInfoLog(program, len, ptr::null_mut(), buf.as_mut_ptr() as *mut GLchar);
panic!("{}", str::from_utf8(buf.as_slice()).ok().expect("ProgramInfoLog not valid utf8"));
}
program
}
}
@SirVer
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SirVer commented May 19, 2017

This was tremendously useful to me, thank you!

@Ryan1729
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Ryan1729 commented Jul 13, 2017

I also found this useful, but when I actually got a shader compilation error the program just crashed. Instead of a Vec I ended up using a [u8; 512] as done here

@Mimerme
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Mimerme commented May 15, 2021

An updated version for anyone who needs one https://gist.github.com/Mimerme/541001baa2dd2ebebd1a57aea5ba5a8e

Thanks for the template! Was having some trouble with porting the C

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