veloren/voxygen/src/render/pipelines/fluid.rs

use super::super::{AaMode, GlobalsLayouts};
use bytemuck::{Pod, Zeroable};
use vek::*;

#[repr(C)]
#[derive(Copy, Clone, Debug, Zeroable, Pod)]
pub struct Vertex {
    pos_norm: u32,
}

impl Vertex {
    #[allow(clippy::identity_op)] // TODO: Pending review in #587
    #[allow(clippy::into_iter_on_ref)] // TODO: Pending review in #587
    pub fn new(pos: Vec3<f32>, norm: Vec3<f32>) -> Self {
        let (norm_axis, norm_dir) = norm
            .as_slice()
            .into_iter()
            .enumerate()
            .find(|(_i, e)| **e != 0.0)
            .unwrap_or((0, &1.0));
        let norm_bits = ((norm_axis << 1) | if *norm_dir > 0.0 { 1 } else { 0 }) as u32;

        const EXTRA_NEG_Z: f32 = 65536.0;

        Self {
            pos_norm: 0
                | ((pos.x as u32) & 0x003F) << 0
                | ((pos.y as u32) & 0x003F) << 6
                | (((pos.z + EXTRA_NEG_Z).max(0.0).min((1 << 17) as f32) as u32) & 0x1FFFF) << 12
                | (norm_bits & 0x7) << 29,
        }
    }

    fn desc<'a>() -> wgpu::VertexBufferDescriptor<'a> {
        use std::mem;
        const ATTRIBUTES: [wgpu::VertexAttributeDescriptor; 1] =
            wgpu::vertex_attr_array![0 => Uint];
        wgpu::VertexBufferDescriptor {
            stride: mem::size_of::<Self>() as wgpu::BufferAddress,
            step_mode: wgpu::InputStepMode::Vertex,
            attributes: &ATTRIBUTES,
        }
    }
}

pub struct FluidLayout {
    pub waves: wgpu::BindGroupLayout,
}

impl FluidLayout {
    pub fn new(device: &wgpu::Device) -> Self {
        Self {
            waves: device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
                label: None,
                entries: &[
                    wgpu::BindGroupLayoutEntry {
                        binding: 0,
                        visibility: wgpu::ShaderStage::VERTEX | wgpu::ShaderStage::FRAGMENT,
                        ty: wgpu::BindingType::SampledTexture {
                            component_type: wgpu::TextureComponentType::Float,
                            dimension: wgpu::TextureViewDimension::D2,
                            multisampled: false,
                        },
                        count: None,
                    },
                    wgpu::BindGroupLayoutEntry {
                        binding: 1,
                        visibility: wgpu::ShaderStage::VERTEX | wgpu::ShaderStage::FRAGMENT,
                        ty: wgpu::BindingType::Sampler { comparison: false },
                        count: None,
                    },
                ],
            }),
        }
    }
}

pub struct FluidPipeline {
    pub pipeline: wgpu::RenderPipeline,
}

impl FluidPipeline {
    pub fn new(
        device: &wgpu::Device,
        vs_module: &wgpu::ShaderModule,
        fs_module: &wgpu::ShaderModule,
        sc_desc: &wgpu::SwapChainDescriptor,
        global_layout: &GlobalsLayouts,
        layout: &FluidLayout,
        aa_mode: AaMode,
    ) -> Self {
        let render_pipeline_layout =
            device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
                label: Some("Fluid pipeline layout"),
                push_constant_ranges: &[],
                bind_group_layouts: &[&global_layout.globals, &layout.waves],
            });

        let samples = match aa_mode {
            AaMode::None | AaMode::Fxaa => 1,
            // TODO: Ensure sampling in the shader is exactly between the 4 texels
            AaMode::SsaaX4 => 1,
            AaMode::MsaaX4 => 4,
            AaMode::MsaaX8 => 8,
            AaMode::MsaaX16 => 16,
        };

        let render_pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
            label: Some("Fluid pipeline"),
            layout: Some(&render_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::None,
                polygon_mode: wgpu::PolygonMode::Fill,
                clamp_depth: false,
                depth_bias: 0,
                depth_bias_slope_scale: 0.0,
                depth_bias_clamp: 0.0,
            }),
            primitive_topology: wgpu::PrimitiveTopology::TriangleList,
            color_states: &[wgpu::ColorStateDescriptor {
                format: sc_desc.format,
                color_blend: wgpu::BlendDescriptor {
                    src_factor: wgpu::BlendFactor::SrcAlpha,
                    dst_factor: wgpu::BlendFactor::OneMinusSrcAlpha,
                    operation: wgpu::BlendOperation::Add,
                },
                alpha_blend: wgpu::BlendDescriptor {
                    src_factor: wgpu::BlendFactor::One,
                    dst_factor: wgpu::BlendFactor::One,
                    operation: wgpu::BlendOperation::Add,
                },
                write_mask: wgpu::ColorWrite::ALL,
            }],
            depth_stencil_state: Some(wgpu::DepthStencilStateDescriptor {
                format: wgpu::TextureFormat::Depth24Plus,
                depth_write_enabled: false,
                depth_compare: wgpu::CompareFunction::LessEqual,
                stencil: wgpu::StencilStateDescriptor {
                    front: wgpu::StencilStateFaceDescriptor::IGNORE,
                    back: wgpu::StencilStateFaceDescriptor::IGNORE,
                    read_mask: !0,
                    write_mask: !0,
                },
            }),
            vertex_state: wgpu::VertexStateDescriptor {
                index_format: wgpu::IndexFormat::Uint16,
                vertex_buffers: &[Vertex::desc()],
            },
            sample_count: samples,
            sample_mask: !0,
            alpha_to_coverage_enabled: false,
        });

        Self {
            pipeline: render_pipeline,
        }
    }
}