use imgui::Context;
use std::mem;
use gl::*;
use gl::types::*;
pub struct ImguiRenderer {
program: GLuint,
locs: Locs,
vbo: GLuint,
ebo: GLuint,
font_texture: GLuint,
}
struct Locs {
texture: GLint,
proj_mtx: GLint,
position: GLuint,
uv: GLuint,
color: GLuint,
}
impl ImguiRenderer {
pub fn new<F>(
imgui: &mut Context,
load_fn: F,
) -> Self
where
F: FnMut(&'static str) -> *const ::std::os::raw::c_void
{
let _gl = gl::load_with(load_fn);
unsafe {
#[cfg(target_os = "macos")]
let glsl_version = b"#version 150\n\0";
#[cfg(not(target_os = "macos"))]
let glsl_version = b"#version 130\n\0";
let vert_source = b"
uniform mat4 ProjMtx;
in vec2 Position;
in vec2 UV;
in vec4 Color;
out vec2 Frag_UV;
out vec4 Frag_Color;
void main()
{
Frag_UV = UV;
Frag_Color = Color;
gl_Position = ProjMtx * vec4(Position.xy,0,1);
}
\0";
let frag_source = b"
uniform sampler2D Texture;
in vec2 Frag_UV;
in vec4 Frag_Color;
out vec4 Out_Color;
void main()
{
Out_Color = Frag_Color * texture(Texture, Frag_UV.st);
}
\0";
let vert_sources = [glsl_version.as_ptr() as *const GLchar,
vert_source.as_ptr() as *const GLchar];
let vert_sources_len = [glsl_version.len() as GLint - 1,
vert_source.len() as GLint - 1];
let frag_sources = [glsl_version.as_ptr() as *const GLchar,
frag_source.as_ptr() as *const GLchar];
let frag_sources_len = [glsl_version.len() as GLint - 1,
frag_source.len() as GLint - 1];
let program = CreateProgram();
let vert_shader = CreateShader(gl::VERTEX_SHADER);
let frag_shader = CreateShader(gl::FRAGMENT_SHADER);
ShaderSource(vert_shader, 2, vert_sources.as_ptr(), vert_sources_len.as_ptr());
ShaderSource(frag_shader, 2, frag_sources.as_ptr(), frag_sources_len.as_ptr());
CompileShader(vert_shader);
CompileShader(frag_shader);
AttachShader(program, vert_shader);
AttachShader(program, frag_shader);
LinkProgram(program);
DeleteShader(vert_shader);
DeleteShader(frag_shader);
let locs = Locs{
texture: GetUniformLocation(program, b"Texture\0".as_ptr() as _),
proj_mtx: GetUniformLocation(program, b"ProjMtx\0".as_ptr() as _),
position: GetAttribLocation(program, b"Position\0".as_ptr() as _) as _,
uv: GetAttribLocation(program, b"UV\0".as_ptr() as _) as _,
color: GetAttribLocation(program, b"Color\0".as_ptr() as _) as _,
};
let vbo = return_param(|x| GenBuffers(1, x) );
let ebo = return_param(|x| GenBuffers(1, x) );
let mut current_texture = 0;
GetIntegerv(gl::TEXTURE_BINDING_2D, &mut current_texture);
let font_texture = return_param(|x| GenTextures(1, x));
BindTexture(gl::TEXTURE_2D, font_texture);
TexParameteri(gl::TEXTURE_2D, gl::TEXTURE_MIN_FILTER, gl::LINEAR as _);
TexParameteri(gl::TEXTURE_2D, gl::TEXTURE_MAG_FILTER, gl::LINEAR as _);
PixelStorei(gl::UNPACK_ROW_LENGTH, 0);
{
let atlas = imgui.fonts();
let texture = atlas.build_rgba32_texture();
TexImage2D(gl::TEXTURE_2D, 0, gl::RGBA as _, texture.width as _, texture.height as _, 0, gl::RGBA, gl::UNSIGNED_BYTE, texture.data.as_ptr() as _);
atlas.tex_id = (font_texture as usize).into();
}
BindTexture(gl::TEXTURE_2D, current_texture as _);
Self{
program,
locs,
vbo,
ebo,
font_texture,
}
}
}
pub fn render(
&self,
ctx: &mut Context,
) {
use imgui::{DrawVert,DrawIdx,DrawCmd,DrawCmdParams};
unsafe {
let last_active_texture = return_param(|x| GetIntegerv(gl::ACTIVE_TEXTURE, x));
ActiveTexture(gl::TEXTURE0);
let last_program = return_param(|x| GetIntegerv(gl::CURRENT_PROGRAM, x));
let last_texture = return_param(|x| GetIntegerv(gl::TEXTURE_BINDING_2D, x));
let last_sampler = if BindSampler::is_loaded() { return_param(|x| GetIntegerv(gl::SAMPLER_BINDING, x)) } else { 0 };
let last_array_buffer = return_param(|x| GetIntegerv(gl::ARRAY_BUFFER_BINDING, x));
let last_element_array_buffer = return_param(|x| GetIntegerv(gl::ELEMENT_ARRAY_BUFFER_BINDING, x));
let last_vertex_array = return_param(|x| GetIntegerv(gl::VERTEX_ARRAY_BINDING, x));
let last_polygon_mode = return_param(|x: &mut [GLint; 2]| GetIntegerv(gl::POLYGON_MODE, x.as_mut_ptr()));
let last_viewport = return_param(|x: &mut [GLint; 4]| GetIntegerv(gl::VIEWPORT, x.as_mut_ptr()));
let last_scissor_box = return_param(|x: &mut [GLint; 4]| GetIntegerv(gl::SCISSOR_BOX, x.as_mut_ptr()));
let last_blend_src_rgb = return_param(|x| GetIntegerv(gl::BLEND_SRC_RGB, x));
let last_blend_dst_rgb = return_param(|x| GetIntegerv(gl::BLEND_DST_RGB, x));
let last_blend_src_alpha = return_param(|x| GetIntegerv(gl::BLEND_SRC_ALPHA, x));
let last_blend_dst_alpha = return_param(|x| GetIntegerv(gl::BLEND_DST_ALPHA, x));
let last_blend_equation_rgb = return_param(|x| GetIntegerv(gl::BLEND_EQUATION_RGB, x));
let last_blend_equation_alpha = return_param(|x| GetIntegerv(gl::BLEND_EQUATION_ALPHA, x));
let last_enable_blend = IsEnabled(gl::BLEND) == gl::TRUE;
let last_enable_cull_face = IsEnabled(gl::CULL_FACE) == gl::TRUE;
let last_enable_depth_test = IsEnabled(gl::DEPTH_TEST) == gl::TRUE;
let last_enable_scissor_test = IsEnabled(gl::SCISSOR_TEST) == gl::TRUE;
Enable(gl::BLEND);
BlendEquation(gl::FUNC_ADD);
BlendFunc(gl::SRC_ALPHA, gl::ONE_MINUS_SRC_ALPHA);
Disable(gl::CULL_FACE);
Disable(gl::DEPTH_TEST);
Enable(gl::SCISSOR_TEST);
PolygonMode(gl::FRONT_AND_BACK, gl::FILL);
let [width, height] = ctx.io().display_size;
let [scale_w, scale_h] = ctx.io().display_framebuffer_scale;
let fb_width = width * scale_w;
let fb_height = height * scale_h;
Viewport(0, 0, fb_width as _, fb_height as _);
let matrix = [
[ 2.0 / width as f32, 0.0, 0.0, 0.0],
[ 0.0, 2.0 / -(height as f32), 0.0, 0.0],
[ 0.0, 0.0, -1.0, 0.0],
[-1.0, 1.0, 0.0, 1.0],
];
UseProgram(self.program);
Uniform1i(self.locs.texture, 0);
UniformMatrix4fv(self.locs.proj_mtx, 1, gl::FALSE, matrix.as_ptr() as _);
if BindSampler::is_loaded() { BindSampler(0, 0); }
let vao = return_param(|x| GenVertexArrays(1, x));
BindVertexArray(vao);
BindBuffer(gl::ARRAY_BUFFER, self.vbo);
EnableVertexAttribArray(self.locs.position);
EnableVertexAttribArray(self.locs.uv);
EnableVertexAttribArray(self.locs.color);
VertexAttribPointer(self.locs.position, 2, gl::FLOAT, gl::FALSE, mem::size_of::<DrawVert>() as _, field_offset::<DrawVert, _, _>(|v| &v.pos) as _);
VertexAttribPointer(self.locs.uv, 2, gl::FLOAT, gl::FALSE, mem::size_of::<DrawVert>() as _, field_offset::<DrawVert, _, _>(|v| &v.uv) as _);
VertexAttribPointer(self.locs.color, 4, gl::UNSIGNED_BYTE, gl::TRUE, mem::size_of::<DrawVert>() as _, field_offset::<DrawVert, _, _>(|v| &v.col) as _);
let draw_data = ctx.render();
for draw_list in draw_data.draw_lists() {
let vtx_buffer = draw_list.vtx_buffer();
let idx_buffer = draw_list.idx_buffer();
BindBuffer(gl::ARRAY_BUFFER, self.vbo);
BufferData(gl::ARRAY_BUFFER, (vtx_buffer.len() * mem::size_of::<DrawVert>()) as _, vtx_buffer.as_ptr() as _, gl::STREAM_DRAW);
BindBuffer(gl::ELEMENT_ARRAY_BUFFER, self.ebo);
BufferData(gl::ELEMENT_ARRAY_BUFFER, (idx_buffer.len() * mem::size_of::<DrawIdx>()) as _, idx_buffer.as_ptr() as _, gl::STREAM_DRAW);
for cmd in draw_list.commands() {
match cmd {
DrawCmd::Elements {
count,
cmd_params: DrawCmdParams {
clip_rect: [x, y, z, w],
texture_id,
idx_offset,
..
},
} => {
BindTexture(gl::TEXTURE_2D, texture_id.id() as _);
Scissor((x * scale_w) as GLint,
(fb_height - w * scale_h) as GLint,
((z - x) * scale_w) as GLint,
((w - y) * scale_h) as GLint);
let idx_size = if mem::size_of::<DrawIdx>() == 2 { gl::UNSIGNED_SHORT } else { gl::UNSIGNED_INT };
DrawElements(gl::TRIANGLES, count as _, idx_size, (idx_offset * mem::size_of::<DrawIdx>()) as _);
},
DrawCmd::ResetRenderState => {
unimplemented!("Haven't implemented DrawCmd::ResetRenderState yet");
},
DrawCmd::RawCallback { .. } => {
unimplemented!("Haven't implemented user callbacks yet");
}
}
}
}
DeleteVertexArrays(1, &vao);
UseProgram(last_program as _);
BindTexture(gl::TEXTURE_2D, last_texture as _);
if BindSampler::is_loaded() { BindSampler(0, last_sampler as _); }
ActiveTexture(last_active_texture as _);
BindVertexArray(last_vertex_array as _);
BindBuffer(gl::ARRAY_BUFFER, last_array_buffer as _);
BindBuffer(gl::ELEMENT_ARRAY_BUFFER, last_element_array_buffer as _);
BlendEquationSeparate(last_blend_equation_rgb as _, last_blend_equation_alpha as _);
BlendFuncSeparate(last_blend_src_rgb as _, last_blend_dst_rgb as _, last_blend_src_alpha as _, last_blend_dst_alpha as _);
if last_enable_blend { Enable(gl::BLEND) } else { Disable(gl::BLEND) };
if last_enable_cull_face { Enable(gl::CULL_FACE) } else { Disable(gl::CULL_FACE) };
if last_enable_depth_test { Enable(gl::DEPTH_TEST) } else { Disable(gl::DEPTH_TEST) };
if last_enable_scissor_test { Enable(gl::SCISSOR_TEST) } else { Disable(gl::SCISSOR_TEST) };
PolygonMode(gl::FRONT_AND_BACK, last_polygon_mode[0] as _);
Viewport(last_viewport[0] as _, last_viewport[1] as _, last_viewport[2] as _, last_viewport[3] as _);
Scissor(last_scissor_box[0] as _, last_scissor_box[1] as _, last_scissor_box[2] as _, last_scissor_box[3] as _);
}
}
}
impl Drop for ImguiRenderer {
fn drop(&mut self) {
unsafe {
DeleteBuffers(1, &self.vbo);
DeleteBuffers(1, &self.ebo);
DeleteProgram(self.program);
DeleteTextures(1, &self.font_texture);
}
}
}
fn field_offset<T, U, F: for<'a> FnOnce(&'a T) -> &'a U>(f: F) -> usize {
unsafe {
let instance = mem::zeroed::<T>();
let offset = {
let field: &U = f(&instance);
field as *const U as usize - &instance as *const T as usize
};
mem::forget(instance);
offset
}
}
fn return_param<T, F>(f: F) -> T where F: FnOnce(&mut T) {
let mut val = unsafe{ mem::zeroed() };
f(&mut val);
val
}