render: implement fxaa (#8)

lyra-game/src/render/graph/passes/fxaa.rs

@@ -0,0 +1,171 @@
+use std::{collections::HashMap, rc::Rc};
+
+use lyra_game_derive::RenderGraphLabel;
+
+use crate::render::{
+    graph::{Node, NodeDesc, NodeType},
+    resource::{FragmentState, PipelineDescriptor, RenderPipelineDescriptor, Shader, VertexState},
+};
+
+#[derive(Default, Debug, Clone, Copy, Hash, RenderGraphLabel)]
+pub struct FxaaPassLabel;
+
+#[derive(Debug, Default)]
+pub struct FxaaPass {
+    target_sampler: Option<wgpu::Sampler>,
+    bgl: Option<Rc<wgpu::BindGroupLayout>>,
+    /// Store bind groups for the input textures.
+    /// The texture may change due to resizes, or changes to the view target chain
+    /// from other nodes.
+    bg_cache: HashMap<wgpu::Id, wgpu::BindGroup>,
+}
+
+impl FxaaPass {
+    pub fn new() -> Self {
+        Self::default()
+    }
+}
+
+impl Node for FxaaPass {
+    fn desc(
+        &mut self,
+        graph: &mut crate::render::graph::RenderGraph,
+    ) -> crate::render::graph::NodeDesc {
+        let device = &graph.device;
+
+        let bgl = device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+            label: Some("fxaa_bgl"),
+            entries: &[
+                wgpu::BindGroupLayoutEntry {
+                    binding: 0,
+                    visibility: wgpu::ShaderStages::FRAGMENT,
+                    ty: wgpu::BindingType::Texture {
+                        sample_type: wgpu::TextureSampleType::Float { filterable: true },
+                        view_dimension: wgpu::TextureViewDimension::D2,
+                        multisampled: false,
+                    },
+                    count: None,
+                },
+                wgpu::BindGroupLayoutEntry {
+                    binding: 1,
+                    visibility: wgpu::ShaderStages::FRAGMENT,
+                    ty: wgpu::BindingType::Sampler(wgpu::SamplerBindingType::Filtering),
+                    count: None,
+                },
+            ],
+        });
+        let bgl = Rc::new(bgl);
+        self.bgl = Some(bgl.clone());
+        self.target_sampler = Some(device.create_sampler(&wgpu::SamplerDescriptor {
+            label: Some("fxaa sampler"),
+            mag_filter: wgpu::FilterMode::Linear,
+            min_filter: wgpu::FilterMode::Linear,
+            mipmap_filter: wgpu::FilterMode::Linear,
+            ..Default::default()
+        }));
+
+        let shader = Rc::new(Shader {
+            label: Some("fxaa_shader".into()),
+            source: include_str!("../../shaders/fxaa.wgsl").to_string(),
+        });
+
+        let vt = graph.view_target();
+        
+        NodeDesc::new(
+            NodeType::Render,
+            Some(PipelineDescriptor::Render(RenderPipelineDescriptor {
+                label: Some("fxaa_pass".into()),
+                layouts: vec![bgl.clone()],
+                push_constant_ranges: vec![],
+                vertex: VertexState {
+                    module: shader.clone(),
+                    entry_point: "vs_main".into(),
+                    buffers: vec![],
+                },
+                fragment: Some(FragmentState {
+                    module: shader,
+                    entry_point: "fs_main".into(),
+                    targets: vec![Some(wgpu::ColorTargetState {
+                        format: vt.format(),
+                        blend: Some(wgpu::BlendState::REPLACE),
+                        write_mask: wgpu::ColorWrites::ALL,
+                    })],
+                }),
+                depth_stencil: None,
+                primitive: wgpu::PrimitiveState::default(),
+                multisample: wgpu::MultisampleState::default(),
+                multiview: None,
+            })),
+            vec![],
+        )
+    }
+
+    fn prepare(
+        &mut self,
+        _: &mut crate::render::graph::RenderGraph,
+        _: &mut lyra_ecs::World,
+        _: &mut crate::render::graph::RenderGraphContext,
+    ) {
+        //todo!()
+    }
+
+    fn execute(
+        &mut self,
+        graph: &mut crate::render::graph::RenderGraph,
+        _: &crate::render::graph::NodeDesc,
+        context: &mut crate::render::graph::RenderGraphContext,
+    ) {
+        let pipeline = graph
+            .pipeline(context.label.clone())
+            .expect("Failed to find pipeline for FxaaPass");
+
+        let mut vt = graph.view_target_mut();
+        let chain = vt.get_chain();
+        let source_view = chain.source.frame_view.as_ref().unwrap();
+        let dest_view = chain.dest.frame_view.as_ref().unwrap();
+
+        let bg = self
+            .bg_cache
+            .entry(source_view.global_id())
+            .or_insert_with(|| {
+                graph
+                    .device()
+                    .create_bind_group(&wgpu::BindGroupDescriptor {
+                        label: Some("fxaa_bg"),
+                        layout: self.bgl.as_ref().unwrap(),
+                        entries: &[
+                            wgpu::BindGroupEntry {
+                                binding: 0,
+                                resource: wgpu::BindingResource::TextureView(source_view),
+                            },
+                            wgpu::BindGroupEntry {
+                                binding: 1,
+                                resource: wgpu::BindingResource::Sampler(
+                                    self.target_sampler.as_ref().unwrap(),
+                                ),
+                            },
+                        ],
+                    })
+            });
+
+        {
+            let encoder = context.encoder.as_mut().unwrap();
+            let mut pass = encoder.begin_render_pass(&wgpu::RenderPassDescriptor {
+                label: Some("fxaa_pass"),
+                color_attachments: &[Some(wgpu::RenderPassColorAttachment {
+                    view: dest_view,
+                    resolve_target: None,
+                    ops: wgpu::Operations {
+                        load: wgpu::LoadOp::Load,
+                        store: true,
+                    },
+                })],
+                depth_stencil_attachment: None,
+            });
+            pass.set_pipeline(pipeline.as_render());
+
+            pass.set_bind_group(0, bg, &[]);
+            pass.draw(0..3, 0..1);
+        }
+    }
+}

lyra-game/src/render/graph/passes/mod.rs

@@ -18,3 +18,6 @@ pub use init::*;
 
 mod tint;
 pub use tint::*;
+
+mod fxaa;
+pub use fxaa::*;

lyra-game/src/render/renderer.rs

@@ -9,7 +9,7 @@ use lyra_game_derive::RenderGraphLabel;
 use tracing::{debug, instrument, warn};
 use winit::window::Window;
 
-use crate::render::graph::{BasePass, BasePassLabel, BasePassSlots, LightBasePass, LightBasePassLabel, LightCullComputePass, LightCullComputePassLabel, MeshPass, MeshesPassLabel, PresentPass, PresentPassLabel, RenderGraphLabelValue, RenderTarget, SubGraphNode, TintPass, TintPassLabel, ViewTarget};
+use crate::render::graph::{BasePass, BasePassLabel, BasePassSlots, FxaaPass, FxaaPassLabel, LightBasePass, LightBasePassLabel, LightCullComputePass, LightCullComputePassLabel, MeshPass, MeshesPassLabel, PresentPass, PresentPassLabel, RenderGraphLabelValue, RenderTarget, SubGraphNode, ViewTarget};
 
 use super::graph::RenderGraph;
 use super::{resource::RenderPipeline, render_job::RenderJob};
@@ -164,8 +164,8 @@ impl BasicRenderer {
             ));
         }
 
-        main_graph.add_node(TintPassLabel, TintPass::default());
-        main_graph.add_edge(TestSubGraphLabel, TintPassLabel);
+        main_graph.add_node(FxaaPassLabel, FxaaPass::default());
+        main_graph.add_edge(TestSubGraphLabel, FxaaPassLabel);
 
         //let present_pass_label = PresentPassLabel::new(BasePassSlots::Frame);//TintPassSlots::Frame);
         let p = PresentPass;

lyra-game/src/render/shaders/fxaa.wgsl

@@ -0,0 +1,263 @@
+// Largely based off of https://blog.simonrodriguez.fr/articles/2016/07/implementing_fxaa.html
+
+const EDGE_THRESHOLD_MIN: f32 = 0.0312;
+const EDGE_THRESHOLD_MAX: f32 = 0.125;
+const ITERATIONS: i32 = 12;
+const SUBPIXEL_QUALITY: f32 = 0.75;
+
+@group(0) @binding(0)
+var t_screen: texture_2d<f32>;
+@group(0) @binding(1)
+var s_screen: sampler;
+
+struct VertexOutput {
+    @builtin(position)
+    clip_position: vec4<f32>,
+    @location(0)
+    tex_coords: vec2<f32>,
+}
+
+fn QUALITY(q: i32) -> f32 {
+    switch (q) {
+        default:              { return 1.0; }
+        case 5:               { return 1.5; }
+        case 6, 7, 8, 9:      { return 2.0; }
+        case 10:              { return 4.0; }
+        case 11:              { return 8.0; }
+    }
+}
+
+fn rgb2luma(rgb: vec3<f32>) -> f32 {
+    return sqrt(dot(rgb, vec3<f32>(0.299, 0.587, 0.114)));
+}
+
+@vertex
+fn vs_main(
+    @builtin(vertex_index) vertex_index: u32,
+) -> VertexOutput {
+    let tex_coords = vec2<f32>(f32(vertex_index >> 1u), f32(vertex_index & 1u)) * 2.0;
+    let clip_position = vec4<f32>(tex_coords * vec2<f32>(2.0, -2.0) + vec2<f32>(-1.0, 1.0), 0.0, 1.0);
+
+    return VertexOutput(clip_position, tex_coords);
+}
+
+fn texture_offset(tex: texture_2d<f32>, samp: sampler, point: vec2<f32>, offset: vec2<i32>) -> vec3<f32> {
+    var tex_coords = point + vec2<f32>(offset);
+    return textureSample(tex, samp, tex_coords).xyz;
+}
+
+@fragment
+fn fs_main(in: VertexOutput) -> @location(0) vec4<f32> {
+    let resolution = vec2<f32>(textureDimensions(t_screen));
+    let inverse_screen_size = 1.0 / resolution.xy;
+    let tex_coords = in.clip_position.xy * inverse_screen_size;
+
+    var color_center: vec3<f32> = textureSampleLevel(t_screen, s_screen, tex_coords, 0.0).xyz;
+    
+    // Luma at the current fragment
+    let luma_center = rgb2luma(color_center);
+
+    // Luma at the four direct neighbours of the current fragment.
+    let luma_down = rgb2luma(textureSampleLevel(t_screen, s_screen, tex_coords, 0.0, vec2<i32>(0, -1)).xyz);
+    let luma_up = rgb2luma(textureSampleLevel(t_screen, s_screen, tex_coords, 0.0, vec2<i32>(0, 1)).xyz);
+    let luma_left = rgb2luma(textureSampleLevel(t_screen, s_screen, tex_coords, 0.0, vec2<i32>(-1, 0)).xyz);
+    let luma_right = rgb2luma(textureSampleLevel(t_screen, s_screen, tex_coords, 0.0, vec2<i32>(1, 0)).xyz);
+
+    // Find the maximum and minimum luma around the current fragment.
+    let luma_min = min(luma_center, min(min(luma_down, luma_up), min(luma_left, luma_right)));
+    let luma_max = max(luma_center, max(max(luma_down, luma_up), max(luma_left, luma_right)));
+
+    // Compute the delta
+    let luma_range = luma_max - luma_min;
+
+    // If the luma variation is lower that a threshold (or if we are in a really dark area),
+    // we are not on an edge, don't perform any AA.
+    if (luma_range < max(EDGE_THRESHOLD_MIN, luma_max * EDGE_THRESHOLD_MAX)) {
+        return vec4<f32>(color_center, 1.0);
+    }
+
+    // Query the 4 remaining corners lumas
+    let luma_down_left = rgb2luma(textureSampleLevel(t_screen, s_screen, tex_coords, 0.0, vec2<i32>(-1, -1)).xyz);
+    let luma_up_right = rgb2luma(textureSampleLevel(t_screen, s_screen, tex_coords, 0.0, vec2<i32>(1, 1)).xyz);
+    let luma_up_left = rgb2luma(textureSampleLevel(t_screen, s_screen, tex_coords, 0.0, vec2<i32>(-1, 1)).xyz);
+    let luma_down_right = rgb2luma(textureSampleLevel(t_screen, s_screen, tex_coords, 0.0, vec2<i32>(1, -1)).xyz);
+
+    // Combine the four edges lumas (using intermediary variables for future computations with the same values).
+    let luma_down_up = luma_down + luma_up;
+    let luma_left_right = luma_left + luma_right;
+
+    // Same for corners
+    let luma_left_corners = luma_down_left + luma_up_left;
+    let luma_down_corners = luma_down_left + luma_down_right;
+    let luma_right_corners = luma_down_right + luma_up_right;
+    let luma_up_corners = luma_up_right + luma_up_left;
+
+    // Compute an estimation of the gradient along the horizontal and verical axis.
+    let edge_horizontal = abs(-2.0 * luma_left + luma_left_corners)
+                        + abs(-2.0 * luma_center + luma_down_up) * 2.0
+                        + abs(-2.0 * luma_right + luma_right_corners);
+    let edge_vertical = abs(-2.0 * luma_up + luma_up_corners)
+                      + abs(-2.0 * luma_center + luma_left_right) * 2.0
+                      + abs(-2.0 * luma_down + luma_down_corners);
+
+    // Is the local edge horizontal or vertical?
+    let is_horizontal = edge_horizontal >= edge_vertical;
+
+    // Select the two neighboring texels lumas in the opposite direction to the local edge.
+    let luma1 = select(luma_left, luma_down, is_horizontal);
+    let luma2 = select(luma_right, luma_up, is_horizontal);
+
+    // Compute gradients in this direction
+    let gradient1 = luma1 - luma_center;
+    let gradient2 = luma2 - luma_center;
+
+    // Which direction is the steepest?
+    let is_1_steepest = abs(gradient1) >= abs(gradient2);
+
+    // Gradient in the corresponding direction, normalized
+    let gradient_scaled = 0.25 * max(abs(gradient1), abs(gradient2));
+
+    // Choose the step size (one pixel) according to the edge direction.
+    var step_length: f32;
+    if (is_horizontal) {
+        step_length = inverse_screen_size.y;
+    } else {
+        step_length = inverse_screen_size.x;
+    }
+
+    // Average luma in the correct direction.
+    var luma_local_average = 0.0;
+    if (is_1_steepest) {
+        // Switch the direction
+        step_length = -step_length;
+        luma_local_average = 0.5 * (luma1 + luma_center);
+    } else {
+        luma_local_average = 0.5 * (luma2 + luma_center);
+    }
+
+    // Shift UV in the correct direction by half a pixel.
+    var current_uv = tex_coords;
+    if (is_horizontal) {
+        current_uv.y += step_length * 0.5;
+    } else {
+        current_uv.x += step_length * 0.5;
+    }
+
+    // Compute offset (for each iteration step) in the right direction.
+    var offset: vec2<f32>;
+    if (is_horizontal) {
+        offset = vec2<f32>(inverse_screen_size.x, 0.0);
+    } else {
+        offset = vec2<f32>(0.0, inverse_screen_size.y);
+    }
+    // Compute UVs to explore on each side of the edge, orthogonally. The QUALITY allows us to
+    // step faster.
+    var uv1 = current_uv - offset;
+    var uv2 = current_uv + offset;
+
+    // Read the lumas at both current extremities of the exploration segment, and compute the
+    // delta wrt to the local average luma.
+    var luma_end1 = rgb2luma(textureSampleLevel(t_screen, s_screen, uv1, 0.0).xyz);
+    var luma_end2 = rgb2luma(textureSampleLevel(t_screen, s_screen, uv2, 0.0).xyz);
+    luma_end1 -= luma_local_average;
+    luma_end2 -= luma_local_average;
+
+    // If the luma deltas at the current extremities are larger than the local gradient, we have
+    // reached the side of the edge.
+    var reached1 = abs(luma_end1) >= gradient_scaled;
+    var reached2 = abs(luma_end2) >= gradient_scaled;
+    var reached_both = reached1 && reached2;
+
+    // If the side is not reached, we continue to explore in this direction.
+    if (!reached1) {
+        uv1 -= offset;
+    }
+    if (!reached2) {
+        uv2 += offset;
+    }
+
+    if (!reached_both) {
+        for (var i = 2; i < ITERATIONS; i++) {
+            // If needed, read luma in 1st direction, compute delta.
+            if (!reached1) {
+                luma_end1 = rgb2luma(textureSampleLevel(t_screen, s_screen, uv1, 0.0).xyz);
+                luma_end1 = luma_end1 - luma_local_average;
+            }
+            // If needed, read luma in opposite direction, compute delta.
+            if (!reached2) {
+                luma_end2 = rgb2luma(textureSampleLevel(t_screen, s_screen, uv2, 0.0).xyz);
+                luma_end2 = luma_end2 - luma_local_average;
+            }
+            // If the luma deltas at the current extremities is larger than the local gradient, we have reached the side of the edge.
+            reached1 = abs(luma_end1) >= gradient_scaled;
+            reached2 = abs(luma_end2) >= gradient_scaled;
+            reached_both = reached1 && reached2;
+
+            // If the side is not reached, we continue to explore in this direction, with a variable quality.
+            if (!reached1) {
+                uv1 -= offset * QUALITY(i);
+            }
+            if (!reached2) {
+                uv2 += offset * QUALITY(i);
+            }
+
+            // If both sides have been reached, stop the exploration
+            if (reached_both) {
+                break;
+            }
+        }
+    }
+
+    // Compute the distances to each extremity of the edge.
+    var distance1 = select(tex_coords.y - uv1.y, tex_coords.x - uv1.x, is_horizontal);
+    var distance2 = select(uv2.y - tex_coords.y, uv2.x - tex_coords.x, is_horizontal);
+
+    // In which direction is the extremity of the edge closer?
+    let is_direction1 = distance1 < distance2;
+    let distance_final = min(distance1, distance2);
+
+    // Length of the edge.
+    let edge_thickness = (distance1 + distance2);
+
+    // UV offset: read in the direction of the closest side of the edge.
+    let pixel_offset = -distance_final / edge_thickness + 0.5;
+
+    // Is the luma at center smaller than the local average?
+    let is_luma_center_smaller = luma_center < luma_local_average;
+
+    // If the luma at center is smaller than at its neighbour, the delta luma at each end should
+    // be positive (same variation). (in the direction of the closer side of the edge.)
+    var direction_luma_end: f32;
+    if (is_direction1) {
+        direction_luma_end = luma_end1;
+    } else {
+        direction_luma_end = luma_end2;
+    }
+    let correct_variation = (direction_luma_end < 0.0) != is_luma_center_smaller;
+
+    // If the luma variation is incorrect, do not offset.
+    var final_offset = select(0.0, pixel_offset, correct_variation);
+ 
+    // Sub-pixel shifting
+    // Full weighted average of the luma over the 3x3 neighborhood.
+    let luma_average = (1.0 / 12.0) * (2.0 * (luma_down_up + luma_left_right) + luma_left_corners + luma_right_corners);
+    // Ratio of the delta between the global average and the center luma, over the luma range
+    // in the 3x3 neighborhood.
+    let sub_pixel_offset1 = clamp(abs(luma_average - luma_center) / luma_range, 0.0, 1.0);
+    let sub_pixel_offset2 = (-2.0 * sub_pixel_offset1 + 3.0) * sub_pixel_offset1 * sub_pixel_offset1;
+    // Compute a sub-pixel offset based on this delta.
+    let sub_pixel_offset_final = sub_pixel_offset2 * sub_pixel_offset2 * SUBPIXEL_QUALITY;
+
+    // Pick the biggest of the two offsets.
+    final_offset = max(final_offset, sub_pixel_offset_final);
+
+    var final_uv = tex_coords;
+    if (is_horizontal) {
+        final_uv.y += final_offset * step_length;
+    } else {
+        final_uv.x += final_offset * step_length;
+    }
+
+    let color = textureSampleLevel(t_screen, s_screen, final_uv, 0.0).xyz;
+    return vec4<f32>(color, 1.0);
+}