Use cube and pyramid primitives

src/main.zig

@@ -47,7 +47,7 @@ depth_texture_view: *gpu.TextureView,
 pipeline: *gpu.RenderPipeline,
 scene_uniform_buffer: *gpu.Buffer,
 scene_uniform_bind_group: *gpu.BindGroup,
-primitive_data: [2]PrimitiveData,
+primitive_data: []PrimitiveData,
 object_data: []ObjectData,
 
 pub fn init(app: *App) !void {
@@ -128,10 +128,15 @@ pub fn init(app: *App) !void {
     }
 
     // Set up the primitives we want to render.
-    app.primitive_data = .{
-        primitives.createTrianglePrimitive(1.0),
-        primitives.createSquarePrimitive(1.0),
-    };
+    // Using `dupe` to allocate a slice here allows easily adjusting the
+    // primitives to use, without changing the type of `primitive_data`.
+    app.primitive_data = try app.allocator.dupe(PrimitiveData, &.{
+        // primitives.createTrianglePrimitive(1.0),
+        // primitives.createSquarePrimitive(0.8),
+        // primitives.createCirclePrimitive(0.5, 24),
+        primitives.createCubePrimitive(0.65),
+        primitives.createPyramidPrimitive(0.75),
+    });
 
     // Set up object related uniform buffers and bind groups.
     // This uploads data to the GPU about all the object we
@@ -239,6 +244,7 @@ pub fn deinit(app: *App) void {
     defer app.pipeline.release();
     defer app.scene_uniform_buffer.release();
     defer app.scene_uniform_bind_group.release();
+    defer app.allocator.free(app.primitive_data);
     defer for (app.primitive_data) |p| {
         p.vertex_buffer.release();
         p.index_buffer.release();

src/primitives.zig

@@ -100,3 +100,110 @@ pub fn createSquarePrimitive(width: f32) PrimitiveData {
         },
     );
 }
+
+pub fn createCirclePrimitive(radius: f32, comptime sides: usize) PrimitiveData {
+    if (sides < 3) @compileError("sides must be at least 3");
+
+    var vertices: [sides]VertexData = undefined;
+    for (&vertices, 0..) |*vertex, i| {
+        const angle = std.math.tau / @as(f32, @floatFromInt(sides)) * @as(f32, @floatFromInt(i));
+        vertex.* = vert(@sin(angle) * radius, @cos(angle) * radius, 0.0);
+    }
+
+    var indices: [(sides - 2) * 3]u32 = undefined;
+    for (0..(sides - 2)) |i| {
+        indices[i * 3 + 0] = 0;
+        indices[i * 3 + 1] = @as(u32, @intCast(i)) + 1;
+        indices[i * 3 + 2] = @as(u32, @intCast(i)) + 2;
+    }
+
+    return createPrimitive(&vertices, &indices);
+}
+
+pub fn createCubePrimitive(width: f32) PrimitiveData {
+    const half_width = width / 2.0;
+    return createPrimitive(
+        // zig fmt: off
+        &.{
+            // Right (+X)
+            vert( half_width,  half_width, -half_width),
+            vert( half_width, -half_width, -half_width),
+            vert( half_width,  half_width,  half_width),
+            vert( half_width, -half_width,  half_width),
+            // Left (-X)
+            vert(-half_width,  half_width,  half_width),
+            vert(-half_width, -half_width,  half_width),
+            vert(-half_width,  half_width, -half_width),
+            vert(-half_width, -half_width, -half_width),
+            // Top (+Y)
+            vert( half_width,  half_width, -half_width),
+            vert( half_width,  half_width,  half_width),
+            vert(-half_width,  half_width, -half_width),
+            vert(-half_width,  half_width,  half_width),
+            // Bottom (-Y)
+            vert(-half_width, -half_width, -half_width),
+            vert(-half_width, -half_width,  half_width),
+            vert( half_width, -half_width, -half_width),
+            vert( half_width, -half_width,  half_width),
+            // Front (+Z)
+            vert( half_width,  half_width,  half_width),
+            vert( half_width, -half_width,  half_width),
+            vert(-half_width,  half_width,  half_width),
+            vert(-half_width, -half_width,  half_width),
+            // Back (-Z)
+            vert(-half_width,  half_width, -half_width),
+            vert(-half_width, -half_width, -half_width),
+            vert( half_width,  half_width, -half_width),
+            vert( half_width, -half_width, -half_width),
+        },
+        &.{
+             0,  1,  2,    3,  2,  1, // Right
+             4,  5,  6,    7,  6,  5, // Left
+             8,  9, 10,   11, 10,  9, // Top
+            12, 13, 14,   15, 14, 13, // Bottom
+            16, 17, 18,   19, 18, 17, // Front
+            20, 21, 22,   23, 22, 21, // Back
+        },
+        // zig fmt: on
+    );
+}
+
+pub fn createPyramidPrimitive(width: f32) PrimitiveData {
+    const half_width = width / 2.0;
+    return createPrimitive(
+        // zig fmt: off
+        &.{
+            // Right
+            vert(        0.0,  half_width,         0.0),
+            vert( half_width, -half_width, -half_width),
+            vert( half_width, -half_width,  half_width),
+            // Left
+            vert(        0.0,  half_width,         0.0),
+            vert(-half_width, -half_width,  half_width),
+            vert(-half_width, -half_width, -half_width),
+            // Front
+            vert(        0.0,  half_width,         0.0),
+            vert( half_width, -half_width,  half_width),
+            vert(-half_width, -half_width,  half_width),
+            // Back
+            vert(        0.0,  half_width,         0.0),
+            vert(-half_width, -half_width, -half_width),
+            vert( half_width, -half_width, -half_width),
+            // Bottom
+            vert(-half_width, -half_width, -half_width),
+            vert(-half_width, -half_width,  half_width),
+            vert( half_width, -half_width, -half_width),
+            vert( half_width, -half_width,  half_width),
+        },
+        &.{
+             0,  1,  2, // Right
+             3,  4,  5, // Left
+             6,  7,  8, // Front
+             9, 10, 11, // Back
+            // Bottom
+            12, 13, 14,
+            15, 14, 13,
+        },
+        // zig fmt: on
+    );
+}