wgpu_examples/render_to_texture/
mod.rs

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1#[cfg(not(target_arch = "wasm32"))]
2use crate::utils::output_image_native;
3#[cfg(target_arch = "wasm32")]
4use crate::utils::output_image_wasm;
5
6const TEXTURE_DIMS: (usize, usize) = (512, 512);
7
8async fn run(_path: Option<String>) {
9    // This will later store the raw pixel value data locally. We'll create it now as
10    // a convenient size reference.
11    let mut texture_data = Vec::<u8>::with_capacity(TEXTURE_DIMS.0 * TEXTURE_DIMS.1 * 4);
12
13    let instance = wgpu::Instance::default();
14    let adapter = instance
15        .request_adapter(&wgpu::RequestAdapterOptions::default())
16        .await
17        .unwrap();
18    let (device, queue) = adapter
19        .request_device(&wgpu::DeviceDescriptor {
20            label: None,
21            required_features: wgpu::Features::empty(),
22            required_limits: wgpu::Limits::downlevel_defaults(),
23            memory_hints: wgpu::MemoryHints::MemoryUsage,
24            trace: wgpu::Trace::Off,
25        })
26        .await
27        .unwrap();
28
29    let shader = device.create_shader_module(wgpu::include_wgsl!("shader.wgsl"));
30
31    let render_target = device.create_texture(&wgpu::TextureDescriptor {
32        label: None,
33        size: wgpu::Extent3d {
34            width: TEXTURE_DIMS.0 as u32,
35            height: TEXTURE_DIMS.1 as u32,
36            depth_or_array_layers: 1,
37        },
38        mip_level_count: 1,
39        sample_count: 1,
40        dimension: wgpu::TextureDimension::D2,
41        format: wgpu::TextureFormat::Rgba8UnormSrgb,
42        usage: wgpu::TextureUsages::RENDER_ATTACHMENT | wgpu::TextureUsages::COPY_SRC,
43        view_formats: &[wgpu::TextureFormat::Rgba8UnormSrgb],
44    });
45    let output_staging_buffer = device.create_buffer(&wgpu::BufferDescriptor {
46        label: None,
47        size: texture_data.capacity() as u64,
48        usage: wgpu::BufferUsages::COPY_DST | wgpu::BufferUsages::MAP_READ,
49        mapped_at_creation: false,
50    });
51
52    let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
53        label: None,
54        layout: None,
55        vertex: wgpu::VertexState {
56            module: &shader,
57            entry_point: Some("vs_main"),
58            compilation_options: Default::default(),
59            buffers: &[],
60        },
61        fragment: Some(wgpu::FragmentState {
62            module: &shader,
63            entry_point: Some("fs_main"),
64            compilation_options: Default::default(),
65            targets: &[Some(wgpu::TextureFormat::Rgba8UnormSrgb.into())],
66        }),
67        primitive: wgpu::PrimitiveState::default(),
68        depth_stencil: None,
69        multisample: wgpu::MultisampleState::default(),
70        multiview: None,
71        cache: None,
72    });
73
74    log::info!("Wgpu context set up.");
75
76    //-----------------------------------------------
77
78    let texture_view = render_target.create_view(&wgpu::TextureViewDescriptor::default());
79
80    let mut command_encoder =
81        device.create_command_encoder(&wgpu::CommandEncoderDescriptor::default());
82    {
83        let mut render_pass = command_encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
84            label: None,
85            color_attachments: &[Some(wgpu::RenderPassColorAttachment {
86                view: &texture_view,
87                depth_slice: None,
88                resolve_target: None,
89                ops: wgpu::Operations {
90                    load: wgpu::LoadOp::Clear(wgpu::Color::GREEN),
91                    store: wgpu::StoreOp::Store,
92                },
93            })],
94            depth_stencil_attachment: None,
95            occlusion_query_set: None,
96            timestamp_writes: None,
97        });
98        render_pass.set_pipeline(&pipeline);
99        render_pass.draw(0..3, 0..1);
100    }
101    // The texture now contains our rendered image
102    command_encoder.copy_texture_to_buffer(
103        wgpu::TexelCopyTextureInfo {
104            texture: &render_target,
105            mip_level: 0,
106            origin: wgpu::Origin3d::ZERO,
107            aspect: wgpu::TextureAspect::All,
108        },
109        wgpu::TexelCopyBufferInfo {
110            buffer: &output_staging_buffer,
111            layout: wgpu::TexelCopyBufferLayout {
112                offset: 0,
113                // This needs to be a multiple of 256. Normally we would need to pad
114                // it but we here know it will work out anyways.
115                bytes_per_row: Some((TEXTURE_DIMS.0 * 4) as u32),
116                rows_per_image: Some(TEXTURE_DIMS.1 as u32),
117            },
118        },
119        wgpu::Extent3d {
120            width: TEXTURE_DIMS.0 as u32,
121            height: TEXTURE_DIMS.1 as u32,
122            depth_or_array_layers: 1,
123        },
124    );
125    queue.submit(Some(command_encoder.finish()));
126    log::info!("Commands submitted.");
127
128    //-----------------------------------------------
129
130    // Time to get our image.
131    let buffer_slice = output_staging_buffer.slice(..);
132    let (sender, receiver) = flume::bounded(1);
133    buffer_slice.map_async(wgpu::MapMode::Read, move |r| sender.send(r).unwrap());
134    device.poll(wgpu::PollType::wait()).unwrap();
135    receiver.recv_async().await.unwrap().unwrap();
136    log::info!("Output buffer mapped.");
137    {
138        let view = buffer_slice.get_mapped_range();
139        texture_data.extend_from_slice(&view[..]);
140    }
141    log::info!("Image data copied to local.");
142    output_staging_buffer.unmap();
143
144    #[cfg(not(target_arch = "wasm32"))]
145    output_image_native(texture_data.to_vec(), TEXTURE_DIMS, _path.unwrap());
146    #[cfg(target_arch = "wasm32")]
147    output_image_wasm(texture_data.to_vec(), TEXTURE_DIMS);
148    log::info!("Done.");
149}
150
151pub fn main() {
152    #[cfg(not(target_arch = "wasm32"))]
153    {
154        env_logger::builder()
155            .filter_level(log::LevelFilter::Info)
156            .format_timestamp_nanos()
157            .init();
158
159        let path = std::env::args()
160            .nth(2)
161            .unwrap_or_else(|| "please_don't_git_push_me.png".to_string());
162        pollster::block_on(run(Some(path)));
163    }
164    #[cfg(target_arch = "wasm32")]
165    {
166        std::panic::set_hook(Box::new(console_error_panic_hook::hook));
167        console_log::init_with_level(log::Level::Info).expect("could not initialize logger");
168        wasm_bindgen_futures::spawn_local(run(None));
169    }
170}
wgpu_examples/render_to_texture/mod.rs

wgpu_examples/render_to_texture/
mod.rs
