[update] mesh rendering in push_constants.

Author: vmarcella

lambda/examples/push_constants.rs

@@ -99,6 +99,24 @@ pub fn push_constants_to_bytes(push_constants: &PushConstant) -> &[u32] {
   return bytes;
 }
 
+fn make_transform(
+  translate: [f32; 3],
+  angle: f32,
+  scale: f32,
+) -> [[f32; 4]; 4] {
+  let c = angle.cos() * scale;
+  let s = angle.sin() * scale;
+
+  let [x, y, z] = translate;
+
+  return [
+    [c, 0.0, s, 0.0],
+    [0.0, scale, 0.0, 0.0],
+    [-s, 0.0, c, 0.0],
+    [x, y, z, 1.0],
+  ];
+}
+
 // --------------------------------- COMPONENT ---------------------------------
 
 pub struct PushConstantsExample {
@@ -190,6 +208,7 @@ impl Component for PushConstantsExample {
   }
 
   fn on_event(&mut self, event: lambda::core::events::Events) {
+    // Only handle resizes.
     match event {
       lambda::core::events::Events::Window { event, issued_at } => {
         match event {
@@ -216,16 +235,12 @@ impl Component for PushConstantsExample {
     render_context: &mut lambda::core::render::RenderContext,
   ) -> Vec<lambda::core::render::command::RenderCommand> {
     self.frame_number += 1;
-    let mut camera = [0.0, 0.0, -2.0];
+    let camera = [0.0, 0.0, -2.0];
     let view: [[f32; 4]; 4] = matrix::translation_matrix(camera);
 
     // Create a projection matrix.
-    let mut projection: [[f32; 4]; 4] = matrix::perspective_matrix(
-      0.25,
-      (self.width / self.height) as f32,
-      0.1,
-      200.0,
-    );
+    let projection: [[f32; 4]; 4] =
+      matrix::perspective_matrix(0.25, (4 / 3) as f32, 0.1, 100.0);
 
     // Rotate model.
     let model: [[f32; 4]; 4] = matrix::rotate_matrix(
@@ -236,6 +251,8 @@ impl Component for PushConstantsExample {
 
     // Create render matrix.
     let mesh_matrix = projection.multiply(&view).multiply(&model);
+    let mesh_matrix =
+      make_transform([0.0, 0.0, 0.5], self.frame_number as f32 * 0.01, 0.5);
 
     // Create viewport.
     let viewport =
@@ -245,7 +262,7 @@ impl Component for PushConstantsExample {
       .render_pipeline
       .expect("No render pipeline actively set for rendering.");
 
-    let mut commands = vec![
+    return vec![
       RenderCommand::SetViewports {
         start_at: 0,
         viewports: vec![viewport.clone()],
@@ -280,11 +297,8 @@ impl Component for PushConstantsExample {
       RenderCommand::Draw {
         vertices: 0..self.mesh.as_ref().unwrap().vertices().len() as u32,
       },
+      RenderCommand::EndRenderPass,
     ];
-
-    commands.push(RenderCommand::EndRenderPass);
-
-    return commands;
   }
 }
 

lambda/src/math/matrix.rs

@@ -103,7 +103,7 @@ pub fn rotate_matrix<
 
   let angle_in_radians = turns_to_radians(angle_in_turns);
   let cosine_of_angle = angle_in_radians.cos();
-  let sin_of_angle = -angle_in_radians.sin();
+  let sin_of_angle = angle_in_radians.sin();
 
   let t = 1.0 - cosine_of_angle;
   let x = axis_to_rotate.at(0);
@@ -112,27 +112,42 @@ pub fn rotate_matrix<
 
   let mut rotation_matrix = OutputMatrix::default();
 
-  let rotation = [
-    [
-      t * x * x + cosine_of_angle,
-      t * x * y - (sin_of_angle * z),
-      t * x * z + (sin_of_angle * y),
-      0.0,
-    ],
-    [
-      t * x * y + (sin_of_angle * z),
-      t * y * y + cosine_of_angle,
-      t * y * z - (sin_of_angle * x),
-      0.0,
-    ],
-    [
-      t * x * z - (sin_of_angle * y),
-      t * y * z - (sin_of_angle * x),
-      t * z * z + cosine_of_angle,
-      0.0,
-    ],
-    [0.0, 0.0, 0.0, 1.0],
-  ];
+  let rotation = match (x as u8, y as u8, z as u8) {
+    (0, 0, 0) => {
+      // No rotation
+      return matrix_to_rotate;
+    }
+    (0, 0, 1) => {
+      // Rotate around z-axis
+      [
+        [cosine_of_angle, sin_of_angle, 0.0, 0.0],
+        [-sin_of_angle, cosine_of_angle, 0.0, 0.0],
+        [0.0, 0.0, 1.0, 0.0],
+        [0.0, 0.0, 0.0, 1.0],
+      ]
+    }
+    (0, 1, 0) => {
+      // Rotate around y-axis
+      [
+        [cosine_of_angle, 0.0, -sin_of_angle, 0.0],
+        [0.0, 1.0, 0.0, 0.0],
+        [sin_of_angle, 0.0, cosine_of_angle, 0.0],
+        [0.0, 0.0, 0.0, 1.0],
+      ]
+    }
+    (1, 0, 0) => {
+      // Rotate around x-axis
+      [
+        [1.0, 0.0, 0.0, 0.0],
+        [0.0, cosine_of_angle, sin_of_angle, 0.0],
+        [0.0, -sin_of_angle, cosine_of_angle, 0.0],
+        [0.0, 0.0, 0.0, 1.0],
+      ]
+    }
+    _ => {
+      panic!("Axis must be a unit vector")
+    }
+  };
 
   for i in 0..rows {
     for j in 0..columns {