Implement playable Mac client and rendering validation

extension/tests/water_depth_test.cpp

@@ -0,0 +1,17 @@
+#include "water_depth.h"
+#include <cassert>
+#include <cstdio>
+#include <limits>
+#include <initializer_list>
+int main() {
+	for (double scale : {0.25, 0.5, 1.0, 2.0}) {
+		assert(mtgodot::water_depth_alpha(-1, scale) == 0);
+		assert(mtgodot::water_depth_alpha(0, scale) == 0);
+		assert(std::abs(mtgodot::water_depth_alpha(100 * scale, scale) - 0.25) < 1e-6);
+		assert(std::abs(mtgodot::water_depth_alpha(320 * scale, scale) - 0.8) < 1e-6);
+		assert(std::abs(mtgodot::water_depth_alpha(1000 * scale, scale) - 0.8) < 1e-6);
+	}
+	assert(mtgodot::water_depth_alpha(100, 0) == 0);
+	assert(mtgodot::water_depth_alpha(std::numeric_limits<double>::quiet_NaN(), 1) == 0);
+	std::puts("PASS: water depth reference (raw depth, shoreline, cap, height scale)");
+}