ferretro/ferretro_components/src/provided/sdl2/opengl.rs

use crate::prelude::*;

use std::ffi::CStr;
use std::os::raw::c_uint;

use sdl2::Sdl;
use sdl2::rect::Rect;
use sdl2::render::WindowCanvas;

// TODO: get these from somewhere better without pulling in too much of a mess for the sdl2 feature
const GL_FRAMEBUFFER_BINDING: c_uint = 0x8CA6;
const GL_COLOR_BUFFER_BIT: c_uint = 0x00004000;

#[allow(non_snake_case)]
pub struct SimpleSdl2OpenglComponent {
    canvas: WindowCanvas,
    window_fbo: c_uint,
    pixel_format: sdl2::pixels::PixelFormatEnum,
    hw_context_reset_fn: Option<HwContextResetFn>,
    hw_context_destroy_fn: Option<HwContextResetFn>,
    glGetIntegerv: unsafe extern "C" fn(c_uint, *mut c_uint),
    glClear: unsafe extern "C" fn(c_uint),
}

impl SimpleSdl2OpenglComponent {
    pub fn new(sdl_context: &mut Sdl, retro: &LibretroWrapper) -> Result<Self, Box<dyn std::error::Error>> {
        let sys_info = retro.get_system_info();
        let title = format!(
            "{} - ferretro SDL GL",
            unsafe { CStr::from_ptr(sys_info.library_name) }.to_string_lossy()
        );

        let geometry = retro.get_system_av_info().geometry;
        let pixel_format = sdl2::pixels::PixelFormatEnum::ARGB1555;

        let video = sdl_context.video()?;
        let window = video
            .window(title.as_str(), geometry.base_width, geometry.base_height)
            .opengl()
            .build()?;

        #[allow(non_snake_case)]
        let glGetIntegerv: unsafe extern "C" fn(c_uint, *mut c_uint) = unsafe {
            std::mem::transmute(video.gl_get_proc_address("glGetIntegerv"))
        };
        #[allow(non_snake_case)]
        let glClear: unsafe extern "C" fn(c_uint) = unsafe {
            std::mem::transmute(video.gl_get_proc_address("glClear"))
        };

        let canvas = window.into_canvas()
            .accelerated()
            .target_texture()
            .build()?;
        // http://forums.libsdl.org/viewtopic.php?p=43353
        // likely to remain `0` on any platform that isn't iOS, but we'll do it anyhow.
        // SDL_CreateRenderer, called by CanvasBuilder::build, creates a new GL Context.
        let window_fbo = unsafe { let mut fbo =  0; glGetIntegerv(GL_FRAMEBUFFER_BINDING, &mut fbo); fbo };

        Ok(SimpleSdl2OpenglComponent {
            canvas,
            window_fbo,
            pixel_format,
            hw_context_reset_fn: None,
            hw_context_destroy_fn: None,
            glGetIntegerv,
            glClear,
        })
    }

    fn current_framebuffer_binding(&self) -> c_uint {
        let mut fbo: c_uint = 0;
        unsafe {
            #[allow(non_snake_case)]
            (self.glGetIntegerv)(GL_FRAMEBUFFER_BINDING, &mut fbo);
        }
        fbo
    }

    fn call_context_reset(&self) -> Option<()> {
        self.hw_context_reset_fn.map(|f| unsafe { f(); })
    }

    fn call_context_destroy(&self) -> Option<()> {
        self.hw_context_destroy_fn.map(|f| unsafe { f(); })
    }
}

impl RetroComponent for SimpleSdl2OpenglComponent {}
impl RetroCallbacks for SimpleSdl2OpenglComponent {
    fn video_refresh(&mut self, data: &[u8], width: u32, height: u32, pitch: u32) {
        let rect = Rect::new(0, 0, width, height);

        if let Ok(mut tex) = self.canvas
            .texture_creator()
            .create_texture_static(self.pixel_format, width, height)
        {
            if tex.update(rect, data, pitch as usize).is_ok() {
                self.canvas.clear();
                self.canvas.copy(&tex, None, None).unwrap();
            }
        }
        self.canvas.present();
    }

    fn video_refresh_hw(&mut self, _width: c_uint, _height: c_uint) {
        self.canvas.present();
        unsafe { (self.glClear)(GL_COLOR_BUFFER_BIT); }
    }

    fn set_pixel_format(&mut self, pix_fmt: PixelFormat) -> Option<bool> {
        self.pixel_format = match pix_fmt {
            PixelFormat::ARGB1555 => sdl2::pixels::PixelFormatEnum::RGB555,
            PixelFormat::ARGB8888 => sdl2::pixels::PixelFormatEnum::ARGB8888,
            PixelFormat::RGB565 => sdl2::pixels::PixelFormatEnum::RGB565,
        };
        Some(true)
    }

    // TODO: depth, stencil, cache_context, bottom_left_origin?
    fn set_hw_render(&mut self, hw_render_callback: &HwRenderCallback) -> Option<bool> {
        self.hw_context_reset_fn.replace(hw_render_callback.context_reset);
        self.hw_context_destroy_fn.replace(hw_render_callback.context_destroy);
        self.call_context_reset();
        Some(true)
    }

    fn get_variable(&mut self, key: &str) -> Option<String> {
        match key {
            "parallel-n64-gfxplugin" => Some("glide64".to_string()),
            _ => None,
        }
    }

    fn set_system_av_info(&mut self, av_info: &SystemAvInfo) -> Option<bool> {
        self.set_geometry(&av_info.geometry)?;
        Some(true)
    }

    fn set_geometry(&mut self, geom: &GameGeometry) -> Option<bool> {
        let _ = self.canvas.window_mut().set_size(geom.base_width, geom.base_height);
        let _ = self.canvas.set_logical_size(geom.base_width, geom.base_height);
        self.window_fbo = self.current_framebuffer_binding();
        /*
        let mut old_canvas = unsafe { MaybeUninit::uninit().assume_init() };
        std::mem::swap(&mut old_canvas, &mut self.canvas);

        // no funny ? operators here because we've got uninitialized memory in self.canvas!
        let mut window = old_canvas.into_window();
        window.set_size(geom.base_width, geom.base_height).unwrap();
        self.call_context_destroy().unwrap();
        let mut new_canvas = window.into_canvas()
            .accelerated()
            .target_texture()
            .build()
            .unwrap();
        self.window_fbo = self.current_framebuffer_binding();

        std::mem::swap(&mut self.canvas, &mut new_canvas);
        std::mem::forget(new_canvas);

        self.call_context_reset()?;
        */
        Some(true)
    }

    fn hw_get_current_framebuffer(&mut self) -> Option<usize> {
        Some(self.window_fbo as usize)
    }

    fn hw_get_proc_address(&mut self, sym: &str) -> Option<*const ()> {
        Some(self.canvas.window().subsystem().gl_get_proc_address(sym))
    }
}

impl Drop for SimpleSdl2OpenglComponent {
    fn drop(&mut self) {
        self.call_context_destroy();
    }
}