Introduce vec2 lib to manage vector 2

tiny-engine/src/commonMain/kotlin/com/github/minigdx/tiny/lua/Vec2Lib.kt

@@ -0,0 +1,144 @@
+package com.github.minigdx.tiny.lua
+
+import com.github.mingdx.tiny.doc.TinyFunction
+import com.github.mingdx.tiny.doc.TinyLib
+import org.luaj.vm2.LuaTable
+import org.luaj.vm2.LuaValue
+import org.luaj.vm2.Varargs
+import org.luaj.vm2.lib.LibFunction
+import org.luaj.vm2.lib.TwoArgFunction
+
+@TinyLib("vec2", "Vector2 manipulation library.")
+class Vec2Lib : TwoArgFunction() {
+    override fun call(arg1: LuaValue, arg2: LuaValue): LuaValue {
+        val vector2 = LuaTable()
+        vector2["create"] = create()
+        vector2["add"] = add()
+        vector2["sub"] = sub()
+        vector2["dot"] = dot()
+        vector2["crs"] = crs()
+        vector2["mag"] = mag()
+        vector2["nor"] = nor()
+        vector2["scl"] = scl()
+        arg2.set("vec2", vector2)
+        arg2.get("package").get("loaded").set("vec2", vector2)
+        return vector2
+    }
+
+    @TinyFunction("Create a vector 2 as a table { x, y }")
+    class create : TwoArgFunction() {
+        override fun call(arg1: LuaValue, arg2: LuaValue): LuaValue {
+            val (x, y) = extract(arg1, arg2)
+            return v2(x, y)
+        }
+
+        override fun call(arg: LuaValue): LuaValue = super.call(arg)
+    }
+
+    @TinyFunction("Add vector2 to another vector2", example = VECTOR2_ADD)
+    class add : LibFunction() {
+        override fun invoke(args: Varargs): Varargs {
+            val (x1, y1, x2, y2) = extract(args)
+            return v2(
+                valueOf(x1.todouble() + x2.todouble()),
+                valueOf(y1.todouble() + y2.todouble()),
+            )
+        }
+    }
+
+    @TinyFunction("Subtract another vector to a vector", example = VECTOR2_SUB)
+    class sub : LibFunction() {
+        override fun invoke(args: Varargs): Varargs {
+            val (x1, y1, x2, y2) = extract(args)
+            return v2(
+                valueOf(x1.todouble() - x2.todouble()),
+                valueOf(y1.todouble() - y2.todouble()),
+            )
+        }
+    }
+
+    @TinyFunction("Dot product between two vectors")
+    class dot : LibFunction() {
+        override fun invoke(args: Varargs): Varargs {
+            val (x1, y1, x2, y2) = extract(args)
+            return valueOf(x1.todouble() * x2.todouble() + y1.todouble() * y2.todouble())
+        }
+    }
+
+    @TinyFunction("Calculate the magnitude (length) of a vector")
+    class mag : LibFunction() {
+        override fun invoke(args: Varargs): Varargs {
+            val (x1, y1) = extract(args)
+            return valueOf(kotlin.math.sqrt(x1.todouble() * x1.todouble() + y1.todouble() * y1.todouble()))
+        }
+    }
+
+    @TinyFunction("Normalize a vector")
+    class nor : LibFunction() {
+        override fun invoke(args: Varargs): Varargs {
+            val (x1, y1) = extract(args)
+            val len = kotlin.math.sqrt(x1.todouble() * x1.todouble() + y1.todouble() * y1.todouble())
+            if (len != 0.0) {
+                return v2(valueOf(x1.todouble() / len), valueOf(y1.todouble() / len))
+            } else {
+                return NIL
+            }
+        }
+    }
+
+    @TinyFunction("Cross product")
+    class crs : LibFunction() {
+        override fun invoke(args: Varargs): Varargs {
+            val (x1, y1, x2, y2) = extract(args)
+            return valueOf(
+                x1.todouble() * y2.todouble() - y1.todouble() * x2.todouble(),
+            )
+        }
+    }
+
+    @TinyFunction("Scale a vector", example = VECTOR2_SCL)
+    class scl : LibFunction() {
+        override fun invoke(args: Varargs): Varargs {
+            val (x1, y1, scale) = extract(args)
+            return v2(valueOf(x1.todouble() * scale.todouble()), valueOf(y1.todouble() * scale.todouble()))
+        }
+    }
+
+    companion object {
+        fun extract(arg1: LuaValue, arg2: LuaValue): List<LuaValue> {
+            return if (arg1.istable()) {
+                listOf(arg1.get("x"), arg2.get("y"))
+            } else {
+                listOf(arg1, arg2)
+            }
+        }
+
+        fun extract(args: Varargs): List<LuaValue> {
+            var index = 1
+            val result = mutableListOf<LuaValue>()
+            var current = args.arg(index)
+            while (index <= args.narg()) {
+                if (current.istable()) {
+                    result.add(current.get("x"))
+                    result.add(current.get("y"))
+                    index++
+                } else {
+                    if (args.narg() - index >= 0) {
+                        result.add(current)
+                        result.add(args.arg(++index))
+                        index++
+                    }
+                }
+                current = args.arg(index)
+            }
+            return result
+        }
+
+        fun v2(arg1: LuaValue, arg2: LuaValue): LuaTable {
+            return LuaTable().apply {
+                set("x", arg1)
+                set("y", arg2)
+            }
+        }
+    }
+}

tiny-engine/src/commonMain/kotlin/com/github/minigdx/tiny/lua/Vec2LibExamples.kt

@@ -0,0 +1,65 @@
+package com.github.minigdx.tiny.lua
+
+//language=Lua
+const val VECTOR2_ADD = """
+function _init()
+    gfx.camera(-128, -128)
+
+    local v1 = vec2.create(32, 38)
+    local v2 = vec2.create(20, 2)
+
+    gfx.cls()
+    print("v1", 2, 15, 10)
+    shape.line(0, 0, v1.x, v1.y, 10)
+    print("v2", 23, 3, 9)
+    shape.line(0, 0, v2.x, v2.y, 9)
+
+    local v3 = vec2.add(v1, v2)
+
+    print("v1 + v2", 30, 15, 11)
+    gfx.dither(0xAAAA)
+    shape.line(0, 0, v3.x, v3.y, 11)
+    gfx.dither()
+end
+"""
+
+//language=Lua
+const val VECTOR2_SUB = """
+function _init()
+    gfx.camera(-128, -128)
+
+    local v1 = vec2.create(32, 38)
+    local v2 = vec2.create(20, 2)
+
+    gfx.cls()
+    print("v1", 18, 15, 10)
+    shape.line(0, 0, v1.x, v1.y, 10)
+    print("v2", 23, 3, 9)
+    shape.line(0, 0, v2.x, v2.y, 9)
+
+    local v3 = vec2.sub(v1, v2)
+
+    print("v1 - v2", 0, 40, 11)
+    gfx.dither(0xAAAA)
+    shape.line(0, 0, v3.x, v3.y, 11)
+    gfx.dither()
+end
+"""
+
+//language=Lua
+const val VECTOR2_SCL = """
+function _init()
+    gfx.camera(-128, -128)
+
+    local v1 = vec2.create(32, 38)
+    local v2 = vec2.scl(v1, 2)
+
+    gfx.cls()
+    print("v1 scaled", 8, 60, 11)
+    gfx.dither(0xAAAA)
+    shape.line(0, 0, v2.x, v2.y, 11)
+    gfx.dither()
+    print("v1", 18, 15, 10)
+    shape.line(0, 0, v1.x, v1.y, 10)
+end
+"""

tiny-engine/src/commonMain/kotlin/com/github/minigdx/tiny/resources/GameScript.kt

@@ -17,6 +17,7 @@ import com.github.minigdx.tiny.lua.SprLib
 import com.github.minigdx.tiny.lua.StdLib
 import com.github.minigdx.tiny.lua.TinyBaseLib
 import com.github.minigdx.tiny.lua.TinyLib
+import com.github.minigdx.tiny.lua.Vec2Lib
 import org.luaj.vm2.Globals
 import org.luaj.vm2.LoadState
 import org.luaj.vm2.LuaError
@@ -83,6 +84,7 @@ class GameScript(
         load(DebugLib(this@GameScript.resourceAccess))
         load(KeysLib())
         load(MathLib())
+        load(Vec2Lib())
         load(tinyLib)
         load(sprLib)
         load(JuiceLib())