Introduce depth buffer finally

src/engine/Texture.zig

@@ -12,6 +12,7 @@ pub const Usage = enum {
     normal,
     occlusion_roughness_metallic,
     emissive,
+    depth,
 
     pub fn vkFormat(self: Usage) vk.Format {
         return switch (self) {
@@ -19,6 +20,7 @@ pub const Usage = enum {
             .normal => .r8g8b8a8_snorm,
             .occlusion_roughness_metallic => .r8g8b8a8_unorm,
             .emissive => .r16g16b16a16_sfloat,
+            .depth => .d32_sfloat,
         };
     }
 
@@ -28,6 +30,7 @@ pub const Usage = enum {
             .normal => 4,
             .occlusion_roughness_metallic => 4,
             .emissive => 4,
+            .depth => 1,
         };
     }
 
@@ -37,6 +40,7 @@ pub const Usage = enum {
             .normal => i8,
             .occlusion_roughness_metallic => u8,
             .emissive => f16,
+            .depth => f32,
         };
     }
 
@@ -80,6 +84,11 @@ pub fn init(engine: *Engine, init_info: InitInfo) !Texture {
     };
     const transfer_queue_family = engine.transfer_queue.allocation.family;
 
+    const queue_family_indices: []const u32 = if (init_info.usage == .depth)
+        &.{target_queue_family}
+    else
+        &.{ target_queue_family, transfer_queue_family };
+
     const image = try engine.createImage(.{
         .image_type = .@"2d",
         .format = init_info.usage.vkFormat(),
@@ -93,10 +102,11 @@ pub fn init(engine: *Engine, init_info: InitInfo) !Texture {
         .samples = .{ .@"1_bit" = true },
         .tiling = .optimal,
         .usage = .{
-            .transfer_dst_bit = true,
-            .sampled_bit = true,
+            .depth_stencil_attachment_bit = init_info.usage == .depth,
+            .transfer_dst_bit = init_info.usage != .depth,
+            .sampled_bit = init_info.usage != .depth,
         },
-        .queue_family_indices = &.{ target_queue_family, transfer_queue_family },
+        .queue_family_indices = queue_family_indices,
         .initial_layout = .undefined,
     });
     errdefer engine.destroyImage(image);
@@ -112,7 +122,10 @@ pub fn init(engine: *Engine, init_info: InitInfo) !Texture {
         .view_type = .@"2d",
         .format = init_info.usage.vkFormat(),
         .subresource_range = .{
-            .aspect_mask = .{ .color_bit = true },
+            .aspect_mask = .{
+                .color_bit = init_info.usage != .depth,
+                .depth_bit = init_info.usage == .depth,
+            },
             .base_mip_level = 0,
             .level_count = 1,
             .base_array_layer = 0,
@@ -167,6 +180,7 @@ pub fn writeRaw(self: Texture, engine: *Engine, data: []const u8) !void {
     const texel_count = try std.math.mul(u32, self.width, self.height);
     const byte_length = try std.math.mul(u32, texel_count, self.usage.bytesPerTexel());
     std.debug.assert(data.len == byte_length);
+    std.debug.assert(self.usage != .depth);
 
     var staging_buffer = try StagingBuffer.init(engine, .{
         .capacity = @intCast(byte_length),