diff --git a/src/main.rs b/src/main.rs
index 1649c2d..eeb1010 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -79,8 +79,10 @@ fn main() {
     let layouts = renderer.get_layouts();
 
     let mesh_pass = pass::mesh::MeshPass::new(device.to_owned(), layouts.to_owned(), viewport.config.format);
+    let debug_pass = pass::debug::DebugPass::new(device.to_owned(), layouts.to_owned(), viewport.config.format);
 
     renderer.add_pass(mesh_pass);
+    renderer.add_pass(debug_pass);
 
     event_loop.run(move |event, _, control_flow| match event {
         Event::RedrawRequested(_) => {
diff --git a/src/pass.rs b/src/pass.rs
index e5c438a..6e881c1 100644
--- a/src/pass.rs
+++ b/src/pass.rs
@@ -3,6 +3,7 @@
 use crate::phase::Phase;
 use std::sync::Arc;
 
+pub mod debug;
 pub mod mesh;
 
 /// Viewport data shared by all passes, once the [ViewportPhase] group is
diff --git a/src/pass/debug.rs b/src/pass/debug.rs
new file mode 100644
index 0000000..fc5b037
--- /dev/null
+++ b/src/pass/debug.rs
@@ -0,0 +1,172 @@
+use super::*;
+use crate::RenderLayouts;
+
+#[repr(C)]
+#[derive(Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
+pub struct Vertex {
+    pub position: [f32; 3],
+    pub color: [f32; 3],
+}
+
+const VERTEX_ATTRS: &[wgpu::VertexAttribute] =
+    &wgpu::vertex_attr_array![0 => Float32x3, 1 => Float32x3];
+
+impl Vertex {
+    pub fn desc() -> wgpu::VertexBufferLayout<'static> {
+        wgpu::VertexBufferLayout {
+            array_stride: std::mem::size_of::<Self>() as wgpu::BufferAddress,
+            step_mode: wgpu::VertexStepMode::Vertex,
+            attributes: VERTEX_ATTRS,
+        }
+    }
+}
+
+pub type Index = u32;
+
+pub struct FrameData {
+    vertex_capacity: usize,
+    vertices: wgpu::Buffer,
+    index_capacity: usize,
+    indices: wgpu::Buffer,
+    index_num: usize,
+}
+
+pub struct DebugPass {
+    device: Arc<wgpu::Device>,
+    pipeline: wgpu::RenderPipeline,
+    target_format: wgpu::TextureFormat,
+}
+
+impl DebugPass {
+    pub fn new(
+        device: Arc<wgpu::Device>,
+        layouts: Arc<RenderLayouts>,
+        target_format: wgpu::TextureFormat,
+    ) -> Self {
+        let shader = device.create_shader_module(&wgpu::include_wgsl!("mesh_shader.wgsl"));
+
+        let pipeline_layout = device.create_pipeline_layout(&wgpu::PipelineLayoutDescriptor {
+            label: Some("DebugPass Pipeline Layout"),
+            bind_group_layouts: &[&layouts.bind_viewport],
+            push_constant_ranges: &[],
+        });
+
+        let pipeline = device.create_render_pipeline(&wgpu::RenderPipelineDescriptor {
+            label: Some("DebugPass Pipeline"),
+            layout: Some(&pipeline_layout),
+            vertex: wgpu::VertexState {
+                module: &shader,
+                entry_point: "vs_main",
+                buffers: &[Vertex::desc()],
+            },
+            fragment: Some(wgpu::FragmentState {
+                module: &shader,
+                entry_point: "fs_main",
+                targets: &[wgpu::ColorTargetState {
+                    format: target_format,
+                    blend: Some(wgpu::BlendState::REPLACE),
+                    write_mask: wgpu::ColorWrites::ALL,
+                }],
+            }),
+            primitive: wgpu::PrimitiveState {
+                topology: wgpu::PrimitiveTopology::LineList,
+                strip_index_format: None,
+                front_face: wgpu::FrontFace::Ccw,
+                cull_mode: None,
+                polygon_mode: wgpu::PolygonMode::Fill,
+                unclipped_depth: false,
+                conservative: false,
+            },
+            depth_stencil: None,
+            multisample: wgpu::MultisampleState {
+                count: 1,
+                mask: !0,
+                alpha_to_coverage_enabled: false,
+            },
+            multiview: None,
+        });
+
+        Self {
+            device,
+            pipeline,
+            target_format,
+        }
+    }
+}
+
+impl RenderPass for DebugPass {
+    type FrameData = FrameData;
+
+    fn create_frame_data(&self) -> FrameData {
+        let vertex_capacity = 1024 * 1024; // TODO resizable buffers
+        let vertices = self.device.create_buffer(&wgpu::BufferDescriptor {
+            label: Some("DebugPass Vertex Buffer"),
+            size: (vertex_capacity * std::mem::size_of::<Vertex>()) as wgpu::BufferAddress,
+            mapped_at_creation: false,
+            usage: wgpu::BufferUsages::VERTEX | wgpu::BufferUsages::COPY_DST,
+        });
+
+        let index_capacity = 1024 * 1024; // TODO resizable buffers
+        let indices = self.device.create_buffer(&wgpu::BufferDescriptor {
+            label: Some("DebugPass Index Buffer"),
+            size: (index_capacity * std::mem::size_of::<Index>()) as wgpu::BufferAddress,
+            mapped_at_creation: false,
+            usage: wgpu::BufferUsages::INDEX | wgpu::BufferUsages::COPY_DST,
+        });
+
+        let index_num = 0;
+
+        FrameData {
+            vertex_capacity,
+            vertices,
+            index_capacity,
+            indices,
+            index_num,
+        }
+    }
+
+    fn begin_frame(&self, data: &mut FrameData, phases: &mut Vec<Phase>, queue: &wgpu::Queue) {
+        phases.push(Phase::Overlay);
+
+        let vertices = &[
+            Vertex {
+                position: [0.0, 0.0, -1.0],
+                color: [1.0, 0.0, 0.0],
+            },
+            Vertex {
+                position: [0.0, 0.0, 1.0],
+                color: [0.0, 0.0, 1.0],
+            },
+        ];
+        queue.write_buffer(&data.vertices, 0, bytemuck::cast_slice(vertices));
+
+        let indices = &[0u32, 1u32];
+        queue.write_buffer(&data.indices, 0, bytemuck::cast_slice(indices));
+
+        data.index_num = 2;
+    }
+
+    fn record_render(&self, data: PhaseData<&FrameData>) -> Option<wgpu::RenderBundle> {
+        println!("DebugPass::record_render(phase: {:?})", data.phase);
+
+        let mut cmds =
+            self.device
+                .create_render_bundle_encoder(&wgpu::RenderBundleEncoderDescriptor {
+                    label: Some("DebugPass Render Bundle"),
+                    color_formats: &[self.target_format],
+                    depth_stencil: None,
+                    sample_count: 1,
+                    multiview: None,
+                });
+
+        cmds.set_pipeline(&self.pipeline);
+        cmds.set_bind_group(0, data.bind_viewport, &[]);
+        cmds.set_vertex_buffer(0, data.frame_data.vertices.slice(..));
+        cmds.set_index_buffer(data.frame_data.indices.slice(..), wgpu::IndexFormat::Uint32);
+
+        let index_range = 0..(data.frame_data.index_num as u32);
+        cmds.draw_indexed(index_range, 0, 0..1);
+
+        Some(cmds.finish(&wgpu::RenderBundleDescriptor::default()))
+    }
+}