From b5ced3af46c96ceb959fbbf1addfeba3bd4f76d5 Mon Sep 17 00:00:00 2001
From: Jon Santmyer <jon@jonsantmyer.com>
Date: Wed, 15 Apr 2026 16:53:58 -0400
Subject: first commit. working body rendering

---
 src/canvas.rs | 176 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 176 insertions(+)
 create mode 100644 src/canvas.rs

(limited to 'src/canvas.rs')

diff --git a/src/canvas.rs b/src/canvas.rs
new file mode 100644
index 0000000..dbcac7f
--- /dev/null
+++ b/src/canvas.rs
@@ -0,0 +1,176 @@
+use wgpu::RenderPipeline;
+
+use crate::wgpuctx::WgpuCtx;
+use crate::texture::Texture;
+use crate::vertex::Vertex;
+use crate::wgpuctx::pipeline::RenderPipelineBuilder;
+
+struct CanvasTexture
+{
+    pub texture: Texture,
+    buffer: wgpu::Buffer
+}
+
+pub struct Canvas
+{
+    pipeline: wgpu::RenderPipeline,
+    vertex_buffer: wgpu::Buffer,
+    texture: CanvasTexture,
+    
+    position: winit::dpi::LogicalPosition<f32>,
+    size: winit::dpi::LogicalSize<f32>
+}
+
+impl Canvas
+{
+    fn create_canvas_texture(
+        wgpuctx: &WgpuCtx,
+        canvas_size: winit::dpi::LogicalSize<f32>,
+        window_size: winit::dpi::PhysicalSize<u32>)
+    -> CanvasTexture
+    {
+        let canvas_physical_size = winit::dpi::PhysicalSize::<u32>::new(
+            (window_size.width as f32 * canvas_size.width).floor() as u32,
+            (window_size.height as f32 * canvas_size.height).floor() as u32
+        );
+
+        CanvasTexture::new(wgpuctx, canvas_physical_size)
+    }
+
+    pub fn new(
+        wgpuctx: &WgpuCtx,
+        window_size: winit::dpi::PhysicalSize<u32>,
+        position: winit::dpi::LogicalPosition<f32>,
+        size: winit::dpi::LogicalSize<f32>
+    ) -> Result<Self, ()> {
+
+        let pos_x = position.x * 2.0 - 1.0;
+        let pos_y = position.y * 2.0 - 1.0;
+        let size_x = size.width * 2.0;
+        let size_y = size.height * 2.0;
+
+        let vertices: &[Vertex] = &[
+            Vertex { position: [ pos_x,        pos_y,        0.0 ], uv: [ 0.0, 1.0 ] },
+            Vertex { position: [ pos_x+size_x, pos_y,        0.0 ], uv: [ 1.0, 1.0 ] },
+            Vertex { position: [ pos_x+size_x, pos_y+size_y, 0.0 ], uv: [ 1.0, 0.0 ] },
+            Vertex { position: [ pos_x+size_x, pos_y+size_y, 0.0 ], uv: [ 1.0, 0.0 ] },
+            Vertex { position: [ pos_x,        pos_y+size_y, 0.0 ], uv: [ 0.0, 0.0 ] },
+            Vertex { position: [ pos_x,        pos_y,        0.0 ], uv: [ 0.0, 1.0 ] },
+        ];
+
+        let vertex_buffer = wgpuctx.create_buffer_init(
+            &wgpu::util::BufferInitDescriptor {
+                label: Some("Vertex Buffer"),
+                contents: bytemuck::cast_slice(vertices),
+                usage: wgpu::BufferUsages::VERTEX
+            }
+        );
+
+        let shader = wgpuctx.create_shader(
+            wgpu::include_wgsl!(concat!(
+                    env!("CARGO_MANIFEST_DIR"), 
+                    "/assets/shaders/canvas.wgsl")
+        ));
+
+        let canvas_texture = Canvas::create_canvas_texture(wgpuctx, size, window_size);
+
+        let render_pipeline = RenderPipelineBuilder::new(
+            &shader)
+            .add_bindgroup(&canvas_texture.texture.bindgrouplayout)
+            .add_vertex_layout(Vertex::descr())
+            .build(Some("Canvas render pipleine"), wgpuctx);
+        
+        Ok(Self {
+            pipeline: render_pipeline,
+            vertex_buffer: vertex_buffer,
+            texture: canvas_texture,
+            position: position,
+            size: size
+        })
+    }
+
+    pub fn resize(
+        &mut self,
+        wgpuctx: &WgpuCtx,
+        width: u32,
+        height: u32)
+    {
+        let window_size = winit::dpi::PhysicalSize::new(width, height);
+        self.texture = Canvas::create_canvas_texture(wgpuctx, self.size, window_size);
+    }
+
+    pub fn present(
+        &mut self,
+        screen_pass: &mut wgpu::RenderPass
+        )
+    -> Result<(), wgpu::SurfaceError> {
+
+        screen_pass.set_pipeline(&self.pipeline);
+        self.texture.texture.use_on_pass(screen_pass, 0);
+        screen_pass.set_vertex_buffer(0, self.vertex_buffer.slice(..));
+        screen_pass.draw(0..6,0..1);
+        Ok(())
+    }
+
+    pub fn view(&self)
+    -> &wgpu::TextureView
+    {
+        self.texture.texture.view()
+    }
+} //impl Canvas
+
+impl CanvasTexture
+{
+    pub fn new(
+        wgpuctx: &WgpuCtx,
+        size: winit::dpi::PhysicalSize<u32>)
+    -> Self
+    {
+        let u32_size = std::mem::size_of::<u32>() as u32;
+        
+        let buffer_size = (u32_size * size.width * size.height) as wgpu::BufferAddress;
+        let buffer_descr = wgpu::BufferDescriptor {
+            size: buffer_size,
+            usage: wgpu::BufferUsages::COPY_DST,
+            label: None,
+            mapped_at_creation: false
+        };
+
+        let texture = wgpuctx.new_render_texture(size);
+        let buffer = wgpuctx.create_buffer(&buffer_descr);
+
+        Self {
+            texture: texture,
+            buffer: buffer
+        }
+    }
+}
+
+impl WgpuCtx
+{
+    pub fn new_render_texture(
+        &self,
+        size: winit::dpi::PhysicalSize<u32>)
+    -> Texture
+    {
+       let descr = wgpu::TextureDescriptor {
+            size: wgpu::Extent3d {
+                width: size.width,
+                height: size.height,
+                depth_or_array_layers: 1
+            },
+            mip_level_count: 1,
+            sample_count: 1,
+            dimension: wgpu::TextureDimension::D2,
+            format: wgpu::TextureFormat::Bgra8UnormSrgb,
+            view_formats: &[
+                wgpu::TextureFormat::Bgra8UnormSrgb
+            ],
+            usage: wgpu::TextureUsages::TEXTURE_BINDING |
+                   wgpu::TextureUsages::COPY_SRC |
+                   wgpu::TextureUsages::RENDER_ATTACHMENT,
+            label: None
+        };
+        self.new_texture(descr)
+    }
+}
-- 
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