[Fix] (MG_Util/ShaderTranspiler): add preprocessing to remove name-collided glsl functions

MobileGL/MG_Util/ShaderTranspiler/ShaderSourceProcessor.cpp

@@ -8,6 +8,89 @@
 
 #include "ShaderSourceProcessor.h"
 
+#include <cctype>
+
+namespace {
+    using MobileGL::SizeT;
+
+    bool IsIdentifierChar(char ch) {
+        return (ch >= '0' && ch <= '9') || (ch >= 'A' && ch <= 'Z') || (ch >= 'a' && ch <= 'z') || ch == '_';
+    }
+
+    bool HasSingleLineFunctionDefinition(const MobileGL::String& source, const MobileGL::String& functionName) {
+        SizeT lineStart = 0;
+        while (lineStart < source.size()) {
+            SizeT lineEnd = source.find('\n', lineStart);
+            if (lineEnd == MobileGL::String::npos) {
+                lineEnd = source.size();
+            }
+
+            SizeT functionPos = source.find(functionName, lineStart);
+            while (functionPos != MobileGL::String::npos && functionPos < lineEnd) {
+                const bool hasLeftBoundary = functionPos == 0 || !IsIdentifierChar(source[functionPos - 1]);
+                const SizeT functionEnd = functionPos + functionName.size();
+                const bool hasRightBoundary =
+                    functionEnd >= source.size() || !IsIdentifierChar(source[functionEnd]);
+                if (hasLeftBoundary && hasRightBoundary) {
+                    SizeT probe = functionEnd;
+                    while (probe < lineEnd && std::isspace(static_cast<unsigned char>(source[probe]))) {
+                        probe++;
+                    }
+                    if (probe < lineEnd && source[probe] == '(') {
+                        const SizeT closingParen = source.find(')', probe);
+                        if (closingParen != MobileGL::String::npos && closingParen < lineEnd) {
+                            probe = closingParen + 1;
+                            while (probe < lineEnd && std::isspace(static_cast<unsigned char>(source[probe]))) {
+                                probe++;
+                            }
+                            if (probe < lineEnd && source[probe] == '{') {
+                                return true;
+                            }
+                        }
+                    }
+                }
+
+                functionPos = source.find(functionName, functionPos + functionName.size());
+            }
+
+            lineStart = lineEnd + 1;
+        }
+
+        return false;
+    }
+
+    void RenameFunctionInvocations(MobileGL::String& source, const MobileGL::String& from, const MobileGL::String& to) {
+        SizeT pos = 0;
+        while ((pos = source.find(from, pos)) != MobileGL::String::npos) {
+            const bool hasLeftBoundary = pos == 0 || !IsIdentifierChar(source[pos - 1]);
+            const SizeT end = pos + from.size();
+            const bool hasRightBoundary = end >= source.size() || !IsIdentifierChar(source[end]);
+
+            SizeT probe = end;
+            while (probe < source.size() && std::isspace(static_cast<unsigned char>(source[probe]))) {
+                probe++;
+            }
+
+            if (hasLeftBoundary && hasRightBoundary && probe < source.size() && source[probe] == '(') {
+                source.replace(pos, from.size(), to);
+                pos += to.size();
+                continue;
+            }
+
+            pos = end;
+        }
+    }
+
+    void RenameBuiltinShadowingFunction(MobileGL::String& source, const char* from, const char* to) {
+        const MobileGL::String fromName = from;
+        if (!HasSingleLineFunctionDefinition(source, fromName)) {
+            return;
+        }
+
+        RenameFunctionInvocations(source, fromName, to);
+    }
+} // namespace
+
 namespace MobileGL {
     namespace MG_Util {
         namespace ShaderTranspiler {
@@ -75,6 +158,10 @@ namespace MobileGL {
                         source = replacement;
                     }
                 }
+
+                // Some shader packs define helpers with built-in GLSL names such as round().
+                // These may pass OpenGL-style validation but fail when recompiled for Vulkan/SPIR-V generation.
+                RenameBuiltinShadowingFunction(source, "round", "mg_round");
             }
 
         } // namespace ShaderTranspiler