a49da033

Add instance upload planning helpers

a73x 2026-04-08 18:44

Commit message

Add instance upload planning helpers

src/renderer.zig

@@ @@ -313,6 +313,28 @@ fn nextInstanceCapacity(current: u32, needed: u32) u32 { @@
+    return capacity;
+const InstanceUploadRequest = struct {
+    current_capacity: u32,
+    offset_instances: u32,
+    write_len: u32,
+};
+const InstanceUploadDecision = struct {
+    needed_capacity: u32,
+    needs_growth: bool,
+    force_full_upload: bool,
+};
+fn planInstanceUpload(req: InstanceUploadRequest) InstanceUploadDecision {
+    const needed_capacity = std.math.add(u32, req.offset_instances, req.write_len) catch std.math.maxInt(u32);
+    const needs_growth = needed_capacity > req.current_capacity;
+    return .{
+        .needed_capacity = needed_capacity,
+        .needs_growth = needs_growth,
+        .force_full_upload = needs_growth,
+    };
+}
+fn swapchainNeedsRebuild(result: vk.Result) bool {
+    return result == .suboptimal_khr;
@@ @@ -1345,3 +1367,25 @@ test "swapchainNeedsRebuild flags suboptimal result" { @@
+    try std.testing.expect(swapchainNeedsRebuild(.suboptimal_khr));
+    try std.testing.expect(!swapchainNeedsRebuild(.success));
+test "range upload falls back to full upload when capacity must grow" {
+    const decision = planInstanceUpload(.{
+        .current_capacity = 8,
+        .offset_instances = 6,
+        .write_len = 4,
+    });
+    try std.testing.expect(decision.needs_growth);
+    try std.testing.expect(decision.force_full_upload);
+}
+test "range upload stays partial when capacity is sufficient" {
+    const decision = planInstanceUpload(.{
+        .current_capacity = 16,
+        .offset_instances = 4,
+        .write_len = 3,
+    });
+    try std.testing.expect(!decision.needs_growth);
+    try std.testing.expect(!decision.force_full_upload);
+}