Fix portability use of std::clamp (#596)

libultraship/libultraship/Lib/Fast3D/gfx_pc.cpp

@@ -33,6 +33,7 @@
 #include "../../Environment.h"
 #include "../../GameVersions.h"
 #include "../../ResourceMgr.h"
+#include "../../Utils.h"
 
 // OTRTODO: fix header files for these
 extern "C" {
@@ -1062,8 +1063,8 @@ static void gfx_sp_vertex(size_t n_vertices, size_t dest_index, const Vtx *verti
                 dotx /= 127.0f;
                 doty /= 127.0f;
 
-                std::clamp(dotx, -1.0f, 1.0f);
-                std::clamp(doty, -1.0f, 1.0f);
+                dotx = math::clamp(dotx, -1.0f, 1.0f);
+                doty = math::clamp(doty, -1.0f, 1.0f);
 
                 if (rsp.geometry_mode & G_TEXTURE_GEN_LINEAR) {
                                     // Not sure exactly what formula we should use to get accurate values
@@ -1115,7 +1116,7 @@ static void gfx_sp_vertex(size_t n_vertices, size_t dest_index, const Vtx *verti
             if (winv < 0.0f) winv = std::numeric_limits<int16_t>::max();
 
             float fog_z = z * winv * rsp.fog_mul + rsp.fog_offset;
-            std::clamp(fog_z, 0.0f, 255.0f);
+            fog_z = math::clamp(fog_z, 0.0f, 255.0f);
             d->color.a = fog_z; // Use alpha variable to store fog factor
         } else {
             d->color.a = v->cn[3];

libultraship/libultraship/Utils.cpp

@@ -5,6 +5,13 @@
 #define strdup _strdup
 #endif
 
+namespace math {
+	float clamp(float d, float min, float max) {
+		const float t = d < min ? min : d;
+		return t > max ? max : t;
+	}
+}
+
 namespace Utils {
 	std::vector<std::string> SplitText(const std::string text, char separator = ' ', bool keep_quotes = false) {
 		std::vector<std::string> args;

libultraship/libultraship/Utils.h

@@ -3,6 +3,10 @@
 #include <string>
 #include <vector>
 
-namespace Utils {
-    std::vector<std::string> SplitText(const std::string& text, char separator, bool keep_quotes);
+namespace math {
+	float clamp(float d, float min, float max);
+}
+
+namespace Utils {
+	std::vector<std::string> SplitText(const std::string& text, char separator, bool keep_quotes);
 }