imgui-wgpu 0.11.0

use bytemuck::{Pod, Zeroable};
use futures::executor::block_on;
use imgui::*;
use imgui_wgpu::{RendererConfig, TextureConfig};
use imgui_winit_support;
use std::time::Instant;
use wgpu::util::DeviceExt;
use winit::{
    dpi::LogicalSize,
    event::{ElementState, Event, KeyboardInput, VirtualKeyCode, WindowEvent},
    event_loop::{ControlFlow, EventLoop},
    window::Window,
};

// Example code modified from https://github.com/gfx-rs/wgpu-rs/tree/master/examples/cube

const OPENGL_TO_WGPU_MATRIX: cgmath::Matrix4<f32> = cgmath::Matrix4::new(
    1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 0.5, 0.0, 0.0, 0.0, 0.5, 1.0,
);

#[repr(C)]
#[derive(Clone, Copy, Pod, Zeroable)]
struct Vertex {
    _pos: [f32; 4],
    _tex_coord: [f32; 2],
}

fn vertex(pos: [i8; 3], tc: [i8; 2]) -> Vertex {
    Vertex {
        _pos: [pos[0] as f32, pos[1] as f32, pos[2] as f32, 1.0],
        _tex_coord: [tc[0] as f32, tc[1] as f32],
    }
}

fn create_vertices() -> (Vec<Vertex>, Vec<u16>) {
    let vertex_data = [
        // top (0, 0, 1)
        vertex([-1, -1, 1], [0, 0]),
        vertex([1, -1, 1], [1, 0]),
        vertex([1, 1, 1], [1, 1]),
        vertex([-1, 1, 1], [0, 1]),
        // bottom (0, 0, -1)
        vertex([-1, 1, -1], [1, 0]),
        vertex([1, 1, -1], [0, 0]),
        vertex([1, -1, -1], [0, 1]),
        vertex([-1, -1, -1], [1, 1]),
        // right (1, 0, 0)
        vertex([1, -1, -1], [0, 0]),
        vertex([1, 1, -1], [1, 0]),
        vertex([1, 1, 1], [1, 1]),
        vertex([1, -1, 1], [0, 1]),
        // left (-1, 0, 0)
        vertex([-1, -1, 1], [1, 0]),
        vertex([-1, 1, 1], [0, 0]),
        vertex([-1, 1, -1], [0, 1]),
        vertex([-1, -1, -1], [1, 1]),
        // front (0, 1, 0)
        vertex([1, 1, -1], [1, 0]),
        vertex([-1, 1, -1], [0, 0]),
        vertex([-1, 1, 1], [0, 1]),
        vertex([1, 1, 1], [1, 1]),
        // back (0, -1, 0)
        vertex([1, -1, 1], [0, 0]),
        vertex([-1, -1, 1], [1, 0]),
        vertex([-1, -1, -1], [1, 1]),
        vertex([1, -1, -1], [0, 1]),
    ];

    let index_data: &[u16] = &[
        0, 1, 2, 2, 3, 0, // top
        4, 5, 6, 6, 7, 4, // bottom
        8, 9, 10, 10, 11, 8, // right
        12, 13, 14, 14, 15, 12, // left
        16, 17, 18, 18, 19, 16, // front
        20, 21, 22, 22, 23, 20, // back
    ];

    (vertex_data.to_vec(), index_data.to_vec())
}

fn create_texels(size: usize) -> Vec<u8> {
    use std::iter;

    (0..size * size)
        .flat_map(|id| {
            // get high five for recognizing this ;)
            let cx = 3.0 * (id % size) as f32 / (size - 1) as f32 - 2.0;
            let cy = 2.0 * (id / size) as f32 / (size - 1) as f32 - 1.0;
            let (mut x, mut y, mut count) = (cx, cy, 0);
            while count < 0xFF && x * x + y * y < 4.0 {
                let old_x = x;
                x = x * x - y * y + cx;
                y = 2.0 * old_x * y + cy;
                count += 1;
            }
            iter::once(0xFF - (count * 5) as u8)
                .chain(iter::once(0xFF - (count * 15) as u8))
                .chain(iter::once(0xFF - (count * 50) as u8))
                .chain(iter::once(1))
        })
        .collect()
}

struct Example {
    vertex_buf: wgpu::Buffer,
    index_buf: wgpu::Buffer,
    index_count: usize,
    bind_group: wgpu::BindGroup,
    uniform_buf: wgpu::Buffer,
    pipeline: wgpu::RenderPipeline,
    time: f32,
}

impl Example {
    fn generate_matrix(aspect_ratio: f32, theta: f32) -> cgmath::Matrix4<f32> {
        let mx_projection = cgmath::perspective(cgmath::Deg(45f32), aspect_ratio, 1.0, 10.0);
        let mx_view = cgmath::Matrix4::look_at(
            cgmath::Point3::new(6.0 * theta.cos(), 6.0 * theta.sin(), 3.0),
            cgmath::Point3::new(0f32, 0.0, 0.0),
            cgmath::Vector3::unit_z(),
        );
        let mx_correction = OPENGL_TO_WGPU_MATRIX;
        mx_correction * mx_projection * mx_view
    }
}

impl Example {
    fn init(
        sc_desc: &wgpu::SwapChainDescriptor,
        device: &wgpu::Device,
        queue: &wgpu::Queue,
    ) -> Self {
        use std::mem;

        // Create the vertex and index buffers
        let vertex_size = mem::size_of::<Vertex>();
        let (vertex_data, index_data) = create_vertices();

        let vertex_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: Some("Vertex Buffer"),
            contents: bytemuck::cast_slice(&vertex_data),
            usage: wgpu::BufferUsage::VERTEX,
        });

        let index_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: Some("Index Buffer"),
            contents: bytemuck::cast_slice(&index_data),
            usage: wgpu::BufferUsage::INDEX,
        });

        // Create pipeline layout
        let bind_group_layout = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
            label: None,
            entries: &[
                wgpu::BindGroupLayoutEntry {
                    binding: 0,
                    visibility: wgpu::ShaderStage::VERTEX,
                    ty: wgpu::BindingType::UniformBuffer {
                        dynamic: false,
                        min_binding_size: wgpu::BufferSize::new(64),
                    },
                    count: None,
                },
                wgpu::BindGroupLayoutEntry {
                    binding: 1,
                    visibility: wgpu::ShaderStage::FRAGMENT,
                    ty: wgpu::BindingType::SampledTexture {
                        multisampled: false,
                        component_type: wgpu::TextureComponentType::Float,
                        dimension: wgpu::TextureViewDimension::D2,
                    },
                    count: None,
                },
                wgpu::BindGroupLayoutEntry {
                    binding: 2,
                    visibility: wgpu::ShaderStage::FRAGMENT,
                    ty: wgpu::BindingType::Sampler { comparison: false },
                    count: None,
                },
            ],
        });
        let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
            label: None,
            bind_group_layouts: &[&bind_group_layout],
            push_constant_ranges: &[],
        });

        // Create the texture
        let size = 256u32;
        let texels = create_texels(size as usize);
        let texture_extent = wgpu::Extent3d {
            width: size,
            height: size,
            depth: 1,
        };
        let texture = device.create_texture(&wgpu::TextureDescriptor {
            label: None,
            size: texture_extent,
            mip_level_count: 1,
            sample_count: 1,
            dimension: wgpu::TextureDimension::D2,
            format: wgpu::TextureFormat::Rgba8UnormSrgb,
            usage: wgpu::TextureUsage::SAMPLED | wgpu::TextureUsage::COPY_DST,
        });
        let texture_view = texture.create_view(&wgpu::TextureViewDescriptor::default());
        queue.write_texture(
            wgpu::TextureCopyView {
                texture: &texture,
                mip_level: 0,
                origin: wgpu::Origin3d::ZERO,
            },
            &texels,
            wgpu::TextureDataLayout {
                offset: 0,
                bytes_per_row: 4 * size,
                rows_per_image: 0,
            },
            texture_extent,
        );

        // Create other resources
        let sampler = device.create_sampler(&wgpu::SamplerDescriptor {
            address_mode_u: wgpu::AddressMode::ClampToEdge,
            address_mode_v: wgpu::AddressMode::ClampToEdge,
            address_mode_w: wgpu::AddressMode::ClampToEdge,
            mag_filter: wgpu::FilterMode::Nearest,
            min_filter: wgpu::FilterMode::Linear,
            mipmap_filter: wgpu::FilterMode::Nearest,
            ..Default::default()
        });
        let mx_total = Self::generate_matrix(sc_desc.width as f32 / sc_desc.height as f32, 0.0);
        let mx_ref: &[f32; 16] = mx_total.as_ref();
        let uniform_buf = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
            label: Some("Uniform Buffer"),
            contents: bytemuck::cast_slice(mx_ref),
            usage: wgpu::BufferUsage::UNIFORM | wgpu::BufferUsage::COPY_DST,
        });

        // Create bind group
        let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
            layout: &bind_group_layout,
            entries: &[
                wgpu::BindGroupEntry {
                    binding: 0,
                    resource: //uniform_buf.as_entire_binding(),
                        wgpu::BindingResource::Buffer(uniform_buf.slice(..)),
                },
                wgpu::BindGroupEntry {
                    binding: 1,
                    resource: wgpu::BindingResource::TextureView(&texture_view),
                },
                wgpu::BindGroupEntry {
                    binding: 2,
                    resource: wgpu::BindingResource::Sampler(&sampler),
                },
            ],
            label: None,
        });

        // Create the render pipeline
        let vs_module =
            device.create_shader_module(wgpu::include_spirv!("../resources/cube.vert.spv"));
        let fs_module =
            device.create_shader_module(wgpu::include_spirv!("../resources/cube.frag.spv"));

        let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: None,
            layout: Some(&pipeline_layout),
            vertex_stage: wgpu::ProgrammableStageDescriptor {
                module: &vs_module,
                entry_point: "main",
            },
            fragment_stage: Some(wgpu::ProgrammableStageDescriptor {
                module: &fs_module,
                entry_point: "main",
            }),
            rasterization_state: Some(wgpu::RasterizationStateDescriptor {
                front_face: wgpu::FrontFace::Ccw,
                cull_mode: wgpu::CullMode::Back,
                ..Default::default()
            }),
            primitive_topology: wgpu::PrimitiveTopology::TriangleList,
            color_states: &[wgpu::ColorStateDescriptor {
                format: sc_desc.format,
                color_blend: wgpu::BlendDescriptor::REPLACE,
                alpha_blend: wgpu::BlendDescriptor::REPLACE,
                write_mask: wgpu::ColorWrite::ALL,
            }],
            depth_stencil_state: None,
            vertex_state: wgpu::VertexStateDescriptor {
                index_format: wgpu::IndexFormat::Uint16,
                vertex_buffers: &[wgpu::VertexBufferDescriptor {
                    stride: vertex_size as wgpu::BufferAddress,
                    step_mode: wgpu::InputStepMode::Vertex,
                    attributes: &[
                        wgpu::VertexAttributeDescriptor {
                            format: wgpu::VertexFormat::Float4,
                            offset: 0,
                            shader_location: 0,
                        },
                        wgpu::VertexAttributeDescriptor {
                            format: wgpu::VertexFormat::Float2,
                            offset: 4 * 4,
                            shader_location: 1,
                        },
                    ],
                }],
            },
            sample_count: 1,
            sample_mask: !0,
            alpha_to_coverage_enabled: false,
        });

        // Done
        Example {
            vertex_buf,
            index_buf,
            index_count: index_data.len(),
            bind_group,
            uniform_buf,
            pipeline,
            time: 0.0,
        }
    }

    fn update(&mut self, delta_time: f32) {
        self.time += delta_time;
    }

    fn setup_camera(&mut self, queue: &wgpu::Queue, size: [f32; 2]) {
        let mx_total = Self::generate_matrix(size[0] / size[1], self.time * 0.1);
        let mx_ref: &[f32; 16] = mx_total.as_ref();
        queue.write_buffer(&self.uniform_buf, 0, bytemuck::cast_slice(mx_ref));
    }

    fn render(&mut self, view: &wgpu::TextureView, device: &wgpu::Device, queue: &wgpu::Queue) {
        let mut encoder =
            device.create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });
        {
            let mut rpass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                color_attachments: &[wgpu::RenderPassColorAttachmentDescriptor {
                    attachment: &view,
                    resolve_target: None,
                    ops: wgpu::Operations {
                        load: wgpu::LoadOp::Clear(wgpu::Color {
                            r: 0.1,
                            g: 0.2,
                            b: 0.3,
                            a: 0.1, // semi-transparent background
                        }),
                        store: true,
                    },
                }],
                depth_stencil_attachment: None,
            });
            rpass.push_debug_group("Prepare data for draw.");
            rpass.set_pipeline(&self.pipeline);
            rpass.set_bind_group(0, &self.bind_group, &[]);
            rpass.set_index_buffer(self.index_buf.slice(..));
            rpass.set_vertex_buffer(0, self.vertex_buf.slice(..));
            rpass.pop_debug_group();
            rpass.insert_debug_marker("Draw!");
            rpass.draw_indexed(0..self.index_count as u32, 0, 0..1);
        }

        queue.submit(Some(encoder.finish()));
    }
}

fn main() {
    wgpu_subscriber::initialize_default_subscriber(None);

    // Set up window and GPU
    let event_loop = EventLoop::new();

    let instance = wgpu::Instance::new(wgpu::BackendBit::PRIMARY);

    let (window, mut size, surface) = {
        let version = env!("CARGO_PKG_VERSION");

        let window = Window::new(&event_loop).unwrap();
        window.set_inner_size(LogicalSize {
            width: 1280.0,
            height: 720.0,
        });
        window.set_title(&format!("imgui-wgpu {}", version));
        let size = window.inner_size();

        let surface = unsafe { instance.create_surface(&window) };

        (window, size, surface)
    };

    let mut hidpi_factor = window.scale_factor();

    let adapter = block_on(instance.request_adapter(&wgpu::RequestAdapterOptions {
        power_preference: wgpu::PowerPreference::HighPerformance,
        compatible_surface: Some(&surface),
    }))
    .unwrap();

    let (device, queue) = block_on(adapter.request_device(
        &wgpu::DeviceDescriptor {
            features: wgpu::Features::empty(),
            limits: wgpu::Limits::default(),
            shader_validation: false,
        },
        None,
    ))
    .unwrap();

    // Set up swap chain
    let mut sc_desc = wgpu::SwapChainDescriptor {
        usage: wgpu::TextureUsage::OUTPUT_ATTACHMENT,
        format: wgpu::TextureFormat::Bgra8Unorm,
        width: size.width as u32,
        height: size.height as u32,
        present_mode: wgpu::PresentMode::Mailbox,
    };

    let mut swap_chain = device.create_swap_chain(&surface, &sc_desc);

    // Set up dear imgui
    let mut imgui = imgui::Context::create();
    let mut platform = imgui_winit_support::WinitPlatform::init(&mut imgui);
    platform.attach_window(
        imgui.io_mut(),
        &window,
        imgui_winit_support::HiDpiMode::Default,
    );
    imgui.set_ini_filename(None);

    let font_size = (13.0 * hidpi_factor) as f32;
    imgui.io_mut().font_global_scale = (1.0 / hidpi_factor) as f32;

    imgui.fonts().add_font(&[FontSource::DefaultFontData {
        config: Some(imgui::FontConfig {
            oversample_h: 1,
            pixel_snap_h: true,
            size_pixels: font_size,
            ..Default::default()
        }),
    }]);

    //
    // Set up dear imgui wgpu renderer
    //
    // let clear_color = wgpu::Color {
    //     r: 0.1,
    //     g: 0.2,
    //     b: 0.3,
    //     a: 1.0,
    // };

    #[cfg(not(feature = "glsl-to-spirv"))]
    let mut renderer = RendererConfig::new()
        .set_texture_format(sc_desc.format)
        .build(&mut imgui, &device, &queue);

    #[cfg(feature = "glsl-to-spirv")]
    let mut renderer = RendererConfig::new_glsl()
        .set_texture_format(sc_desc.format)
        .build(&mut imgui, &device, &queue);

    let mut last_frame = Instant::now();

    let mut last_cursor = None;

    let mut example_size: [f32; 2] = [640.0, 480.0];
    let mut example = Example::init(&sc_desc, &device, &queue);

    // Stores a texture for displaying with imgui::Image(),
    // also as a texture view for rendering into it
    let example_texture_id = renderer.textures.insert(
        TextureConfig::new(example_size[0] as u32, example_size[1] as u32)
            .set_usage(wgpu::TextureUsage::OUTPUT_ATTACHMENT | wgpu::TextureUsage::SAMPLED)
            .build(&device, &renderer),
    );

    // Event loop
    event_loop.run(move |event, _, control_flow| {
        *control_flow = if cfg!(feature = "metal-auto-capture") {
            ControlFlow::Exit
        } else {
            ControlFlow::Poll
        };
        match event {
            Event::WindowEvent {
                event: WindowEvent::ScaleFactorChanged { scale_factor, .. },
                ..
            } => {
                hidpi_factor = scale_factor;
            }
            Event::WindowEvent {
                event: WindowEvent::Resized(_),
                ..
            } => {
                size = window.inner_size();

                sc_desc = wgpu::SwapChainDescriptor {
                    usage: wgpu::TextureUsage::OUTPUT_ATTACHMENT,
                    format: wgpu::TextureFormat::Bgra8Unorm,
                    width: size.width as u32,
                    height: size.height as u32,
                    present_mode: wgpu::PresentMode::Mailbox,
                };

                swap_chain = device.create_swap_chain(&surface, &sc_desc);
            }
            Event::WindowEvent {
                event:
                    WindowEvent::KeyboardInput {
                        input:
                            KeyboardInput {
                                virtual_keycode: Some(VirtualKeyCode::Escape),
                                state: ElementState::Pressed,
                                ..
                            },
                        ..
                    },
                ..
            }
            | Event::WindowEvent {
                event: WindowEvent::CloseRequested,
                ..
            } => {
                *control_flow = ControlFlow::Exit;
            }
            Event::MainEventsCleared => window.request_redraw(),
            Event::RedrawEventsCleared => {
                let now = Instant::now();
                imgui.io_mut().update_delta_time(now - last_frame);
                last_frame = now;

                let frame = match swap_chain.get_current_frame() {
                    Ok(frame) => frame,
                    Err(e) => {
                        eprintln!("dropped frame: {:?}", e);
                        return;
                    }
                };
                platform
                    .prepare_frame(imgui.io_mut(), &window)
                    .expect("Failed to prepare frame");
                let ui = imgui.frame();

                // Render example normally at background
                example.update(ui.io().delta_time);
                example.setup_camera(&queue, ui.io().display_size);
                example.render(&frame.output.view, &device, &queue);

                // Store the new size of Image() or None to indicate that the window is collapsed.
                let mut new_example_size: Option<[f32; 2]> = None;

                imgui::Window::new(im_str!("Cube"))
                    .size([512.0, 512.0], Condition::FirstUseEver)
                    .build(&ui, || {
                        new_example_size = Some(ui.content_region_avail());
                        imgui::Image::new(example_texture_id, new_example_size.unwrap()).build(&ui);
                    });

                match new_example_size {
                    Some(size) => {
                        // Resize render target, which is optional
                        if size != example_size && size[0] >= 1.0 && size[1] >= 1.0 {
                            example_size = size;
                            let scale = &ui.io().display_framebuffer_scale;
                            renderer.textures.replace(
                                example_texture_id,
                                TextureConfig::new(
                                    (example_size[0] * scale[0]) as u32,
                                    (example_size[1] * scale[1]) as u32,
                                )
                                .set_usage(
                                    wgpu::TextureUsage::OUTPUT_ATTACHMENT
                                        | wgpu::TextureUsage::SAMPLED,
                                )
                                .build(&device, &renderer),
                            );
                        }

                        // Only render example to example_texture if thw window is not collapsed
                        example.setup_camera(&queue, size);
                        example.render(
                            &renderer.textures.get(example_texture_id).unwrap().view(),
                            &device,
                            &queue,
                        );
                    }
                    _ => {}
                }

                let mut encoder: wgpu::CommandEncoder =
                    device.create_command_encoder(&wgpu::CommandEncoderDescriptor { label: None });

                if last_cursor != Some(ui.mouse_cursor()) {
                    last_cursor = Some(ui.mouse_cursor());
                    platform.prepare_render(&ui, &window);
                }

                let mut rpass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
                    color_attachments: &[wgpu::RenderPassColorAttachmentDescriptor {
                        attachment: &frame.output.view,
                        resolve_target: None,
                        ops: wgpu::Operations {
                            load: wgpu::LoadOp::Load, // Do not clear
                            // load: wgpu::LoadOp::Clear(clear_color),
                            store: true,
                        },
                    }],
                    depth_stencil_attachment: None,
                });

                renderer
                    .render(ui.render(), &queue, &device, &mut rpass)
                    .expect("Rendering failed");

                drop(rpass);

                queue.submit(Some(encoder.finish()));
            }
            _ => (),
        }

        platform.handle_event(imgui.io_mut(), &window, &event);
    });
}