dynamis-gpu 0.3.0

GPU-driven physics engine
Documentation 
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use crate::buffer::GpuBuffer;
use wgpu::{
    BindGroup, BindGroupEntry, BindGroupLayout, BindGroupLayoutDescriptor, BindGroupLayoutEntry,
    BindingType, BufferBindingType, CommandEncoder, ComputePassDescriptor,
    ComputePipeline as WgpuComputePipeline, ComputePipelineDescriptor, Device,
    PipelineLayoutDescriptor, ShaderModuleDescriptor, ShaderSource, ShaderStages,
};

#[derive(Clone, Copy)]
pub enum BindingKind {
    Uniform,
    ReadOnlyStorage,
    ReadWriteStorage,
}

pub struct BindingSpec {
    pub binding: u32,
    pub kind: BindingKind,
}

pub struct ComputePipeline {
    pipeline: WgpuComputePipeline,
    bind_group_layout: BindGroupLayout,
    workgroup_size: u32,
}

impl ComputePipeline {
    pub fn new(
        device: &Device,
        label: &str,
        shader: &str,
        entry: &str,
        bindings: &[BindingSpec],
        workgroup_size: u32,
    ) -> Self {
        let module = device.create_shader_module(ShaderModuleDescriptor {
            label: Some(label),
            source: ShaderSource::Wgsl(shader.into()),
        });
        let entries: Vec<BindGroupLayoutEntry> = bindings
            .iter()
            .map(|spec| BindGroupLayoutEntry {
                binding: spec.binding,
                visibility: ShaderStages::COMPUTE,
                ty: match spec.kind {
                    BindingKind::Uniform => BindingType::Buffer {
                        ty: BufferBindingType::Uniform,
                        has_dynamic_offset: false,
                        min_binding_size: None,
                    },
                    BindingKind::ReadOnlyStorage => BindingType::Buffer {
                        ty: BufferBindingType::Storage { read_only: true },
                        has_dynamic_offset: false,
                        min_binding_size: None,
                    },
                    BindingKind::ReadWriteStorage => BindingType::Buffer {
                        ty: BufferBindingType::Storage { read_only: false },
                        has_dynamic_offset: false,
                        min_binding_size: None,
                    },
                },
                count: None,
            })
            .collect();
        let bind_group_layout = device.create_bind_group_layout(&BindGroupLayoutDescriptor {
            label: Some(label),
            entries: &entries,
        });
        let pipeline_layout = device.create_pipeline_layout(&PipelineLayoutDescriptor {
            label: Some(label),
            bind_group_layouts: &[Some(&bind_group_layout)],
            immediate_size: 0,
        });
        let pipeline = device.create_compute_pipeline(&ComputePipelineDescriptor {
            label: Some(label),
            layout: Some(&pipeline_layout),
            module: &module,
            entry_point: Some(entry),
            compilation_options: Default::default(),
            cache: None,
        });
        Self {
            pipeline,
            bind_group_layout,
            workgroup_size,
        }
    }

    pub fn bind_group_layout(&self) -> &BindGroupLayout {
        &self.bind_group_layout
    }

    pub fn workgroup_size(&self) -> u32 {
        self.workgroup_size
    }

    pub fn create_bind_group(&self, device: &Device, entries: &[BindGroupEntry<'_>]) -> BindGroup {
        device.create_bind_group(&wgpu::BindGroupDescriptor {
            label: None,
            layout: &self.bind_group_layout,
            entries,
        })
    }

    pub fn workgroup_count(&self, elements: u32) -> u32 {
        elements.div_ceil(self.workgroup_size)
    }

    pub fn record_passes(&self, encoder: &mut CommandEncoder, bind_group: &BindGroup, count: u32) {
        let mut pass = encoder.begin_compute_pass(&ComputePassDescriptor {
            label: None,
            timestamp_writes: None,
        });
        pass.set_pipeline(&self.pipeline);
        pass.set_bind_group(0, bind_group, &[]);
        pass.dispatch_workgroups(count, 1, 1);
    }

    pub fn record_indirect(
        &self,
        encoder: &mut CommandEncoder,
        bind_group: &BindGroup,
        target: &GpuBuffer,
    ) {
        let mut pass = encoder.begin_compute_pass(&ComputePassDescriptor {
            label: None,
            timestamp_writes: None,
        });
        pass.set_pipeline(&self.pipeline);
        pass.set_bind_group(0, bind_group, &[]);
        pass.dispatch_workgroups_indirect(target.as_indirect_target(), 0);
    }
}