1 files changed, 63 insertions, 0 deletions
diff --git a/src/gfx/util.rs b/src/gfx/util.rs
new file mode 100644
index 0000000..f93accd
--- /dev/null
+++ b/src/gfx/util.rs
@@ -0,0 +1,63 @@
+use cgmath::Matrix4;
+use wgpu::util::DeviceExt;
+
+pub struct MatrixUniform {
+    buffer: wgpu::Buffer,
+    pub bind_group: wgpu::BindGroup,
+}
+
+impl MatrixUniform {
+    pub fn new(
+        device: &wgpu::Device,
+        bind_group_layout: &wgpu::BindGroupLayout,
+        init: Matrix4<f32>,
+        name: &str,
+        writable: bool,
+    ) -> Self {
+        let uniform: [[f32; 4]; 4] = init.into();
+
+        let mut usage = wgpu::BufferUsages::UNIFORM;
+
+        if writable {
+            usage |= wgpu::BufferUsages::COPY_DST;
+        }
+
+        let buffer = device.create_buffer_init(&wgpu::util::BufferInitDescriptor {
+            label: Some(&format!("{name}.buffer")),
+            contents: bytemuck::cast_slice(&[uniform]),
+            usage,
+        });
+
+        let bind_group = device.create_bind_group(&wgpu::BindGroupDescriptor {
+            layout: bind_group_layout,
+            entries: &[wgpu::BindGroupEntry {
+                binding: 0,
+                resource: buffer.as_entire_binding(),
+            }],
+            label: Some(&format!("{name}.bind_group")),
+        });
+
+        Self { buffer, bind_group }
+    }
+
+    pub fn layout(device: &wgpu::Device, name: &str) -> wgpu::BindGroupLayout {
+        device.create_bind_group_layout(&wgpu::BindGroupLayoutDescriptor {
+            entries: &[wgpu::BindGroupLayoutEntry {
+                binding: 0,
+                visibility: wgpu::ShaderStages::VERTEX,
+                ty: wgpu::BindingType::Buffer {
+                    ty: wgpu::BufferBindingType::Uniform,
+                    has_dynamic_offset: false,
+                    min_binding_size: None,
+                },
+                count: None,
+            }],
+            label: Some(&format!("{name}.bind_group_layout")),
+        })
+    }
+
+    pub fn set(&self, queue: &wgpu::Queue, to: Matrix4<f32>) {
+        let uniform: [[f32; 4]; 4] = to.into();
+        queue.write_buffer(&self.buffer, 0, bytemuck::cast_slice(&[uniform]));
+    }
+}