Add padding to fix alignment

stevenhuyn · Apr 30, 2023 · b01657b · b01657b
1 parent 3f3e2f4
commit b01657b
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Showing 2 changed files with 7 additions and 14 deletions.
diff --git a/cubeway/src/compute.wgsl b/cubeway/src/compute.wgsl
@@ -4,6 +4,7 @@ struct SimParams {
 
 struct Instance {
     position: vec3<f32>,
+    unused: f32,
     rotation: vec4<f32>,
 }
 
@@ -17,9 +18,8 @@ struct Instances {
 fn main(@builtin(global_invocation_id) GlobalInvocationID: vec3<u32>) {
     var index = GlobalInvocationID.x;
 
-    instanceBuffer[index * 7u].position.y -= 0.001;
 
     if index < 100u {
-        let bufferIndex = u32(f32(index) * 7.0);
+        instanceBuffer[index].position.y -= 0.001;
     }
 }
diff --git a/cubeway/src/lib.rs b/cubeway/src/lib.rs
@@ -57,6 +57,7 @@ impl Vertex {
 #[derive(Debug, Copy, Clone, bytemuck::Pod, bytemuck::Zeroable)]
 struct Instance {
     position: [f32; 3],
+    _pad: f32,
     rotation: [f32; 4],
 }
 
@@ -75,7 +76,7 @@ impl Instance {
                     format: wgpu::VertexFormat::Float32x3,
                 },
                 wgpu::VertexAttribute {
-                    offset: mem::size_of::<[f32; 3]>() as wgpu::BufferAddress,
+                    offset: 16 as wgpu::BufferAddress,
                     shader_location: 3,
                     format: wgpu::VertexFormat::Float32x4,
                 },
@@ -195,20 +196,12 @@ impl State {
                         z: z as f32,
                     } - INSTANCE_DISPLACEMENT;
 
-                    let rotation = if position.is_zero() {
-                        // this is needed so an object at (0, 0, 0) won't get scaled to zero
-                        // as Quaternions can effect scale if they're not created correctly
-                        cgmath::Quaternion::from_axis_angle(
-                            cgmath::Vector3::unit_z(),
-                            cgmath::Deg(0.0),
-                        )
-                    } else {
-                        cgmath::Quaternion::from_axis_angle(position.normalize(), cgmath::Deg(45.0))
-                    };
+                    // let rotation = cgmath::Quaternion::zero();
 
                     Instance {
                         position: position.into(),
-                        rotation: rotation.into(),
+                        _pad: 0.0,
+                        rotation: [1., 0., 0., 0.],
                     }
                 })
             })