Add support for Lua in world, and create the Lua Pattern (pattern can be defined with a lua function)

source/pattern/luapattern.h

@@ -0,0 +1,107 @@
+/*
+ *  DoRayMe - a quick and dirty Raytracer
+ *  Lua based Pattern header
+ *
+ *  Created by Manoël Trapier
+ *  Copyright (c) 2020 986-Studio.
+ *
+ */
+#ifndef DORAYME_LUAPATTERN_H
+#define DORAYME_LUAPATTERN_H
+
+#include <pattern.h>
+#include <stdio.h>
+#include <string.h>
+
+#ifndef ENABLE_LUA_SUPPORT
+#error Cannot use the Lua Pattern generator with no Lua support disabled!
+#endif
+
+extern "C" {
+#include <lua.h>
+}
+
+class LuaPattern : public Pattern
+{
+private:
+    lua_State *L;
+    char funcName[50];
+
+public:
+    LuaPattern(Colour a, Colour b) : Pattern(a, b), L(nullptr) { };
+
+    void setLua(lua_State *L) {
+        this->L = L;
+    };
+
+    void setLuaFunctionName(const char *name) {
+        strncpy(this->funcName, name, 50);
+    }
+
+    Colour patternAt(Tuple point)
+    {
+        int isnum;
+        double r, g, b;
+
+        lua_getglobal(this->L, this->funcName);
+        lua_pushnumber(this->L, point.x);
+        lua_pushnumber(this->L, point.y);
+        lua_pushnumber(this->L, point.z);
+
+        lua_createtable(L, 3, 0);
+        lua_pushnumber(L, this->a.x);
+        lua_setfield(L, -2, "r");
+        lua_pushnumber(L, this->a.y);
+        lua_setfield(L, -2, "g");
+        lua_pushnumber(L, this->a.z);
+        lua_setfield(L, -2, "b");
+
+        lua_createtable(L, 3, 0);
+        lua_pushnumber(L, this->b.x);
+        lua_setfield(L, -2, "r");
+        lua_pushnumber(L, this->b.y);
+        lua_setfield(L, -2, "g");
+        lua_pushnumber(L, this->b.z);
+        lua_setfield(L, -2, "b");
+
+        if (lua_pcall(this->L, 5, 3, 0) != LUA_OK)
+        {
+            printf("Error running the Lua function '%s': %s\n", this->funcName,
+                    lua_tostring(this->L, -1));
+            return Colour(0, 0, 0);
+        }
+
+        r = lua_tonumberx(this->L, -3, &isnum);
+        if (!isnum)
+        {
+            printf("Error: function '%s' must return numbers\n", this->funcName);
+            lua_pop(this->L, 1);
+            return Colour(0, 0, 0);
+        }
+        g = lua_tonumberx(this->L, -2, &isnum);
+        if (!isnum)
+        {
+            printf("Error: function '%s' must return numbers\n", this->funcName);
+            lua_pop(this->L, 1);
+            return Colour(0, 0, 0);
+        }
+        b = lua_tonumberx(this->L, -1, &isnum);
+        if (!isnum)
+        {
+            printf("Error: function '%s' must return numbers\n", this->funcName);
+            lua_pop(this->L, 1);
+            return Colour(0, 0, 0);
+        }
+
+        lua_pop(this->L, 1);
+        return Colour(r, g, b);
+    }
+
+    void dumpMe(FILE *fp) {
+        fprintf(fp, "\"Type\": \"Lua\",\n");
+        Pattern::dumpMe(fp);
+    }
+
+};
+
+#endif /* DORAYME_LUAPATTERN_H */