1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193

use {
    crate::{
        handles::LayerHandle,
        render::{Layouts, Render, Shaders},
        shader::Shader,
        topology::Topology,
        vertex::Vertex,
    },
    std::marker::PhantomData,
    wgpu::{
        BlendState, CompareFunction, Device, PolygonMode, PrimitiveTopology, RenderPipeline,
        TextureFormat,
    },
};

pub(crate) struct Pipeline(RenderPipeline);

impl Pipeline {
    pub fn new(
        device: &Device,
        shaders: &Shaders,
        layouts: &Layouts,
        format: TextureFormat,
        shader: Shader,
        params: PipelineParameters,
    ) -> Self {
        use {crate::depth_frame::DepthFrame, wgpu::*};

        Self({
            let module = shaders.module(device, shader);
            let layout = device.create_pipeline_layout(&PipelineLayoutDescriptor {
                label: None,
                bind_group_layouts: layouts.bind_group_layouts(shader).as_slice(),
                push_constant_ranges: &[],
            });

            device.create_render_pipeline(&RenderPipelineDescriptor {
                label: None,
                layout: Some(&layout),
                vertex: VertexState {
                    module,
                    entry_point: "vs_main",
                    buffers: shader.buffers(),
                },
                fragment: Some(FragmentState {
                    module,
                    entry_point: "fs_main",
                    targets: &[Some(ColorTargetState {
                        format,
                        blend: Some(params.blend),
                        write_mask: ColorWrites::ALL,
                    })],
                }),
                primitive: PrimitiveState {
                    topology: params.topology,
                    strip_index_format: None,
                    front_face: FrontFace::Ccw,
                    cull_mode: params.cull_faces.then_some(Face::Back),
                    polygon_mode: params.mode,
                    unclipped_depth: false,
                    conservative: false,
                },
                depth_stencil: params.depth_stencil.map(|depth_compare| DepthStencilState {
                    format: DepthFrame::DEPTH_FORMAT,
                    depth_write_enabled: true,
                    depth_compare,
                    stencil: StencilState::default(),
                    bias: DepthBiasState::default(),
                }),
                multisample: MultisampleState::default(),
                multiview: None,
            })
        })
    }

    pub fn as_ref(&self) -> &RenderPipeline {
        &self.0
    }
}

/// Builds new layer with specific parameters.
#[must_use]
pub struct ParametersBuilder<'a, V, T> {
    render: &'a mut Render,
    params: PipelineParameters,
    vertex_type: PhantomData<(V, T)>,
}

impl<'a, V, T> ParametersBuilder<'a, V, T> {
    pub(crate) fn new(render: &'a mut Render) -> Self {
        Self {
            render,
            params: PipelineParameters::default(),
            vertex_type: PhantomData,
        }
    }

    pub fn with_blend(mut self, blend: Blend) -> Self {
        self.params.blend = match blend {
            Blend::Replace => BlendState::REPLACE,
            Blend::AlphaBlending => BlendState::ALPHA_BLENDING,
        };

        self
    }

    pub fn with_cull_faces(mut self, cull_faces: bool) -> Self {
        self.params.cull_faces = cull_faces;
        self
    }

    pub fn with_draw_mode(mut self, draw_mode: DrawMode) -> Self {
        self.params.mode = match draw_mode {
            DrawMode::Fill => PolygonMode::Fill,
            DrawMode::Line => PolygonMode::Line,
            DrawMode::Point => PolygonMode::Point,
        };

        self
    }

    pub fn with_depth_compare(mut self, depth_compare: Compare) -> Self {
        self.params.depth_stencil = Some(match depth_compare {
            Compare::Never => CompareFunction::Never,
            Compare::Less => CompareFunction::Less,
            Compare::Greater => CompareFunction::Greater,
            Compare::Always => CompareFunction::Always,
        });

        self
    }

    #[must_use]
    pub fn build(self) -> LayerHandle<V, T>
    where
        V: Vertex,
        T: Topology,
    {
        self.render.create_layer(self.params)
    }
}

#[derive(Clone, Copy)]
pub(crate) struct PipelineParameters {
    pub blend: BlendState,
    pub topology: PrimitiveTopology,
    pub cull_faces: bool,
    pub mode: PolygonMode,
    pub depth_stencil: Option<CompareFunction>,
}

impl Default for PipelineParameters {
    fn default() -> Self {
        Self {
            blend: BlendState::REPLACE,
            topology: PrimitiveTopology::TriangleList,
            cull_faces: true,
            mode: PolygonMode::Fill,
            depth_stencil: Some(CompareFunction::Less),
        }
    }
}

/// Layer's blending
#[derive(Clone, Copy)]
pub enum Blend {
    Replace,
    AlphaBlending,
}

/// Type of drawing mode for polygons
#[derive(Clone, Copy)]
pub enum DrawMode {
    Fill,
    Line,
    Point,
}

/// Depth comparison function
#[derive(Clone, Copy)]
pub enum Compare {
    /// Function never passes
    Never,

    /// Function passes if new value less than existing value
    Less,

    /// Function passes if new value is greater than existing value
    Greater,

    /// Function always passes
    Always,
}