graphics: count occlusion queries on the host GPU behind --occlusion-queries

tests/OcclusionQueriesTests.cpp

@@ -0,0 +1,55 @@
+#include "graphics/host_gpu/renderer/occlusionQueries.h"
+
+#include <array>
+#include <cstdio>
+#include <cstdlib>
+
+namespace {
+using namespace Libs::Graphics;
+
+#define CHECK(condition)                                                                           \
+	do {                                                                                           \
+		if (!(condition)) {                                                                        \
+			std::fprintf(stderr, "OcclusionQueriesTests:%d: %s\n", __LINE__, #condition);          \
+			std::abort();                                                                          \
+		}                                                                                          \
+	} while (false)
+
+using Results = std::array<uint64_t, OCCLUSION_QUERY_DBS * 2>;
+
+// The samples a query passed, as ZPass predication sums them; -1 before every counter is written.
+int64_t Passed(const Results& results) {
+	int64_t samples = 0;
+	for (uint32_t db = 0; db < OCCLUSION_QUERY_DBS; db++) {
+		const auto begin = results[db * 2];
+		const auto end   = results[db * 2 + 1];
+		if ((begin & end & OCCLUSION_QUERY_READY) == 0) {
+			return -1;
+		}
+		samples += static_cast<int64_t>(end - begin);
+	}
+	return samples;
+}
+
+void TestCounters() {
+	Results results {};
+	WriteZPassCounters(results.data(), 100, true);
+	CHECK(Passed(results) == -1);
+	WriteZPassCounters(results.data() + 1, 100, false);
+	CHECK(Passed(results) == 0);
+	WriteZPassCounters(results.data() + 1, 142, false);
+	CHECK(Passed(results) == 42);
+	CHECK(results[0] == (OCCLUSION_QUERY_READY | 100) && results[30] == OCCLUSION_QUERY_READY);
+
+	// A begin clears the end a previous query wrote late, so the query is not ready until its own.
+	WriteZPassCounters(results.data(), 142, true);
+	CHECK(Passed(results) == -1);
+	WriteZPassCounters(results.data() + 1, 150, false);
+	CHECK(Passed(results) == 8);
+}
+} // namespace
+
+int main() {
+	TestCounters();
+	std::puts("Occlusion query tests passed");
+}