[Shader JIT] Add caching

src/core/PICA/dynapica/shader_rec.cpp

@@ -1,7 +1,14 @@
 #include "PICA/dynapica/shader_rec.hpp"
+#include "cityhash.hpp"
 
 #ifdef PANDA3DS_SHADER_JIT_SUPPORTED
+void ShaderJIT::reset() {
+	cache.clear();
+}
+
 void ShaderJIT::prepare(PICAShader& shaderUnit) {
-	printf("HAPPY HAPPY HAPPY\n");
+	// We construct a shader hash from both the code and operand descriptor hashes
+	// This is so that if only one of them changes, we still properly recompile the shader
+	Hash hash = shaderUnit.getCodeHash() ^ shaderUnit.getOpdescHash();
 }
 #endif // PANDA3DS_SHADER_JIT_SUPPORTED