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Add Minimal Offscreen Rendering Example (#2451)
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* add offscreen example

* cleanup example

* more cleanup

* typo

* fix clippy

* Update examples/offscreen/main.rs

Co-authored-by: marc0246 <[email protected]>

* Update examples/offscreen/main.rs

Co-authored-by: marc0246 <[email protected]>

* Update examples/offscreen/main.rs

Co-authored-by: marc0246 <[email protected]>

* edits

* i'm loosing my marbles

* Update examples/offscreen/main.rs

Co-authored-by: marc0246 <[email protected]>

* Update examples/offscreen/main.rs

Co-authored-by: marc0246 <[email protected]>

* formatting

* Update examples/offscreen/Cargo.toml

Co-authored-by: marc0246 <[email protected]>

* Update examples/offscreen/main.rs

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* Update examples/offscreen/main.rs

Co-authored-by: marc0246 <[email protected]>

* Update examples/offscreen/main.rs

Co-authored-by: marc0246 <[email protected]>

* Update examples/offscreen/main.rs

Co-authored-by: marc0246 <[email protected]>

* Update examples/offscreen/main.rs

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* Update examples/offscreen/main.rs

Co-authored-by: marc0246 <[email protected]>

* Update examples/offscreen/main.rs

Co-authored-by: marc0246 <[email protected]>

* Update examples/offscreen/main.rs

Co-authored-by: marc0246 <[email protected]>

* Update examples/offscreen/main.rs

Co-authored-by: marc0246 <[email protected]>

* Update examples/offscreen/main.rs

Co-authored-by: marc0246 <[email protected]>

* Update examples/offscreen/main.rs

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* cargo fmt

* more correct description

* import

* Update examples/offscreen/main.rs

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* Update examples/offscreen/main.rs

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---------

Co-authored-by: marc0246 <[email protected]>
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@0xcaff @marc0246
0xcaff and marc0246 authored Jan 11, 2024
1 parent fd352ec commit 9b6e307
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18 changes: 18 additions & 0 deletions examples/offscreen/Cargo.toml
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[package]
name = "offscreen"
version = "0.0.0"
edition = "2021"
publish = false

[[bin]]
name = "offscreen"
path = "main.rs"
test = false
bench = false
doc = false

[dependencies]
png = { workspace = true }
vulkano = { workspace = true, features = ["macros"] }
vulkano-shaders = { workspace = true }
winit = { workspace = true }
349 changes: 349 additions & 0 deletions examples/offscreen/main.rs
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// Offscreen rendering example, renders a red triangle on a blue background to a buffer in memory
// then exports to a PNG. No swapchains here!

use std::{default::Default, fs::File, io::BufWriter, path::Path, sync::Arc};
use vulkano::{
buffer::{Buffer, BufferContents, BufferCreateInfo, BufferUsage},
command_buffer::{
allocator::StandardCommandBufferAllocator, CommandBufferBeginInfo, CommandBufferLevel,
CommandBufferUsage, CopyImageToBufferInfo, RecordingCommandBuffer, RenderPassBeginInfo,
SubpassBeginInfo, SubpassContents,
},
device::{physical::PhysicalDeviceType, Device, DeviceCreateInfo, QueueCreateInfo, QueueFlags},
format::Format,
image::{view::ImageView, Image, ImageCreateInfo, ImageUsage},
instance::{Instance, InstanceCreateFlags, InstanceCreateInfo},
memory::allocator::{AllocationCreateInfo, MemoryTypeFilter, StandardMemoryAllocator},
pipeline::{
graphics::{
color_blend::{ColorBlendAttachmentState, ColorBlendState},
input_assembly::InputAssemblyState,
multisample::MultisampleState,
rasterization::RasterizationState,
vertex_input::{Vertex, VertexDefinition},
viewport::{Viewport, ViewportState},
GraphicsPipelineCreateInfo,
},
layout::PipelineDescriptorSetLayoutCreateInfo,
GraphicsPipeline, PipelineLayout, PipelineShaderStageCreateInfo,
},
render_pass::{Framebuffer, FramebufferCreateInfo, Subpass},
sync::GpuFuture,
VulkanLibrary,
};

fn main() {
// The start of this example is exactly the same as `triangle`. You should read the `triangle`
// example if you haven't done so yet.

let library = VulkanLibrary::new().unwrap();

let instance = Instance::new(
library,
InstanceCreateInfo {
flags: InstanceCreateFlags::ENUMERATE_PORTABILITY,
..Default::default()
},
)
.unwrap();

let (physical_device, queue_family_index) = instance
.enumerate_physical_devices()
.unwrap()
// No need for swapchain extension support.
.filter_map(|p| {
p.queue_family_properties()
.iter()
.position(|q| q.queue_flags.intersects(QueueFlags::GRAPHICS))
.map(|i| (p, i as u32))
})
.min_by_key(|(p, _)| match p.properties().device_type {
PhysicalDeviceType::DiscreteGpu => 0,
PhysicalDeviceType::IntegratedGpu => 1,
PhysicalDeviceType::VirtualGpu => 2,
PhysicalDeviceType::Cpu => 3,
PhysicalDeviceType::Other => 4,
_ => 5,
})
.expect("no suitable physical device found");

println!(
"Using device: {} (type: {:?})",
physical_device.properties().device_name,
physical_device.properties().device_type,
);

let (device, mut queues) = Device::new(
physical_device.clone(),
DeviceCreateInfo {
queue_create_infos: vec![QueueCreateInfo {
queue_family_index,
..Default::default()
}],
..Default::default()
},
)
.unwrap();

let queue = queues.next().unwrap();

let memory_allocator = Arc::new(StandardMemoryAllocator::new_default(device.clone()));

#[derive(BufferContents, Vertex)]
#[repr(C)]
struct Vertex {
#[format(R32G32_SFLOAT)]
position: [f32; 2],
}

let vertices = [
Vertex {
position: [-0.5, -0.25],
},
Vertex {
position: [0.0, 0.5],
},
Vertex {
position: [0.25, -0.1],
},
];
let vertex_buffer = Buffer::from_iter(
memory_allocator.clone(),
BufferCreateInfo {
usage: BufferUsage::VERTEX_BUFFER,
..Default::default()
},
AllocationCreateInfo {
memory_type_filter: MemoryTypeFilter::PREFER_DEVICE
| MemoryTypeFilter::HOST_SEQUENTIAL_WRITE,
..Default::default()
},
vertices,
)
.unwrap();

mod vs {
vulkano_shaders::shader! {
ty: "vertex",
src: r"
#version 450
layout(location = 0) in vec2 position;
void main() {
gl_Position = vec4(position, 0.0, 1.0);
}
",
}
}

mod fs {
vulkano_shaders::shader! {
ty: "fragment",
src: r"
#version 450
layout(location = 0) out vec4 f_color;
void main() {
f_color = vec4(1.0, 0.0, 0.0, 1.0);
}
",
}
}

let format = Format::R8G8B8A8_UNORM;

let render_pass = vulkano::single_pass_renderpass!(
device.clone(),
attachments: {
color: {
format: format,
samples: 1,
load_op: Clear,
store_op: Store,
},
},
pass: {
color: [color],
depth_stencil: {},
},
)
.unwrap();

// Create an offscreen image for rendering into.
let render_output_image = Image::new(
memory_allocator.clone(),
ImageCreateInfo {
format,
usage: ImageUsage::COLOR_ATTACHMENT | ImageUsage::TRANSFER_SRC,
extent: [1920, 1080, 1],
..Default::default()
},
AllocationCreateInfo::default(),
)
.unwrap();

let render_output_image_view = ImageView::new_default(render_output_image.clone()).unwrap();

let framebuffer = Framebuffer::new(
render_pass.clone(),
FramebufferCreateInfo {
// Attach the offscreen image to the framebuffer.
attachments: vec![render_output_image_view],
..Default::default()
},
)
.unwrap();

let pipeline = {
let vs = vs::load(device.clone())
.unwrap()
.entry_point("main")
.unwrap();
let fs = fs::load(device.clone())
.unwrap()
.entry_point("main")
.unwrap();

let vertex_input_state = Vertex::per_vertex()
.definition(&vs.info().input_interface)
.unwrap();

let stages = [
PipelineShaderStageCreateInfo::new(vs),
PipelineShaderStageCreateInfo::new(fs),
];

let layout = PipelineLayout::new(
device.clone(),
PipelineDescriptorSetLayoutCreateInfo::from_stages(&stages)
.into_pipeline_layout_create_info(device.clone())
.unwrap(),
)
.unwrap();

let subpass = Subpass::from(render_pass.clone(), 0).unwrap();

GraphicsPipeline::new(
device.clone(),
None,
GraphicsPipelineCreateInfo {
stages: stages.into_iter().collect(),
vertex_input_state: Some(vertex_input_state),
input_assembly_state: Some(InputAssemblyState::default()),
viewport_state: Some(ViewportState {
viewports: [Viewport {
offset: [0.0, 0.0],
extent: [1920.0, 1080.0],
depth_range: 0.0..=1.0,
}]
.into_iter()
.collect(),
..Default::default()
}),
rasterization_state: Some(RasterizationState::default()),
multisample_state: Some(MultisampleState::default()),
color_blend_state: Some(ColorBlendState::with_attachment_states(
subpass.num_color_attachments(),
ColorBlendAttachmentState::default(),
)),
subpass: Some(subpass.into()),
..GraphicsPipelineCreateInfo::layout(layout)
},
)
.unwrap()
};

let command_buffer_allocator = Arc::new(StandardCommandBufferAllocator::new(
device.clone(),
Default::default(),
));

// Host-accessible buffer where the offscreen image's contents are copied to after rendering.
let render_output_buf = Buffer::from_iter(
memory_allocator.clone(),
BufferCreateInfo {
usage: BufferUsage::TRANSFER_DST,
..Default::default()
},
AllocationCreateInfo {
memory_type_filter: MemoryTypeFilter::PREFER_HOST
| MemoryTypeFilter::HOST_RANDOM_ACCESS,
..Default::default()
},
(0..(1920 * 1080 * 4)).map(|_| 0u8),
)
.unwrap();

let mut builder = RecordingCommandBuffer::new(
command_buffer_allocator.clone(),
queue.queue_family_index(),
CommandBufferLevel::Primary,
CommandBufferBeginInfo {
usage: CommandBufferUsage::OneTimeSubmit,
..Default::default()
},
)
.unwrap();

builder
.begin_render_pass(
RenderPassBeginInfo {
clear_values: vec![Some([0.0, 0.0, 1.0, 1.0].into())],
// This framebuffer has the offscreen image attached to it.
..RenderPassBeginInfo::framebuffer(framebuffer.clone())
},
SubpassBeginInfo {
contents: SubpassContents::Inline,
..Default::default()
},
)
.unwrap()
.bind_pipeline_graphics(pipeline.clone())
.unwrap()
.bind_vertex_buffers(0, vertex_buffer.clone())
.unwrap();

unsafe {
builder.draw(vertex_buffer.len() as u32, 1, 0, 0).unwrap();
}

builder.end_render_pass(Default::default()).unwrap();

// The output image stores information in an unknown, non-linear layout, optimized for usage on
// the device. This step copies the output image into a host-readable linear output buffer
// where consecutive pixels in the image are laid out consecutively in memory.
builder
.copy_image_to_buffer(CopyImageToBufferInfo::image_buffer(
render_output_image.clone(),
render_output_buf.clone(),
))
.unwrap();

let command_buffer = builder.end().unwrap();

let finished = command_buffer.clone().execute(queue.clone()).unwrap();

finished
.then_signal_fence_and_flush()
.unwrap()
.wait(None)
.unwrap();

// Access the bytes copied into the host-accessible output buffer by reference.
let buffer_content = render_output_buf.read().unwrap();

let path = Path::new(env!("CARGO_MANIFEST_DIR")).join("triangle.png");
let file = File::create(&path).unwrap();
let w = &mut BufWriter::new(file);
let mut encoder = png::Encoder::new(w, 1920, 1080);
encoder.set_color(png::ColorType::Rgba);
encoder.set_depth(png::BitDepth::Eight);
let mut writer = encoder.write_header().unwrap();
writer.write_image_data(&buffer_content).unwrap();

if let Ok(path) = path.canonicalize() {
println!("Saved to {}", path.display());
}
}

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