Add SKN and CMX parser, add HarmonyMath

Author: MrPowerGamerBR

README.md

@@ -57,6 +57,12 @@ By the default the IFF reader does not attempt to decode any of the chunk data,
 * The Sims Online's FAR3 archive are weird... `packingslips.dat` files don't seem to have any name?!
 * It looks like floors in The Sims Complete Collection (not in HomeCrafter, heck, not even in The Sims Legacy Collection!) HATES SPR2 that uses any pixel command except 0x06 and 0x03
   * I think it is because floors are encoded with the flag 1 (only color channel) and, while Legacy Collection and HomeCrafter does not care about that, Complete Collection does care about it and trips out after encountering an unexpected flag.
+* Figuring out how the game handles the SKN <-> CMX <-> BMP relation is confusing...
+  * The game uses the bitmap in the `skn` file, but it ONLY seems to use it for accessories
+  * **TODO:** ACTUALLY DOCUMENT THIS ^^^
+* The reason why we use `harmonymath` instead of JOML is because we want to use the lib on the browser too, which is why we haphazardly ported some of the JOML classes to Kotlin Multiplatform 
+* The SKN/CMX parser seems to work fine, it is used for [SneakySims's Website](https://sneakysims.net) for skin rendering preview
+
 ### Reading SPR# Images and Converting
 
 ```kotlin

harmonymath/README.md

@@ -0,0 +1,7 @@
+# HarmonyMath
+
+Math libraries for Kotlin Multiplatform.
+
+The classes are mostly straight to Kotlin JOML classes. 
+
+For SneakyLib, HarmonyMath is used for quaternions and other 3D model related things, and it is also used in the SneakySims website for 3D skin rendering using WebGL2.

harmonymath/build.gradle.kts

@@ -0,0 +1,53 @@
+plugins {
+    kotlin("multiplatform")
+    id("maven-publish")
+}
+
+group = "net.perfectdreams.harmony.math"
+
+repositories {
+    mavenCentral()
+}
+
+kotlin {
+    jvmToolchain(21)
+
+    jvm {
+        withJava()
+    }
+
+    js(IR) {
+        browser()
+    }
+
+    sourceSets {
+        val commonMain by getting {
+            dependencies {
+                implementation(kotlin("stdlib-common"))
+            }
+        }
+
+        val jsMain by getting {
+            dependencies {
+            }
+        }
+
+        val jvmTest by getting {
+            dependencies {
+                implementation(kotlin("test"))
+                // https://mvnrepository.com/artifact/org.joml/joml
+                implementation("org.joml:joml:1.10.8")
+            }
+        }
+    }
+}
+
+publishing {
+    repositories {
+        maven {
+            name = "PerfectDreams"
+            url = uri("https://repo.perfectdreams.net/")
+            credentials(PasswordCredentials::class)
+        }
+    }
+}

harmonymath/src/commonMain/kotlin/net/perfectdreams/harmony/math/HarmonyMath.kt

@@ -0,0 +1,33 @@
+package net.perfectdreams.harmony.math
+
+import kotlin.math.PI
+import kotlin.math.sqrt
+
+object HarmonyMath {
+    const val PI_f = PI.toFloat()
+    const val PI_OVER_2_f = (PI * 0.5).toFloat()
+    const val PI_TIMES_2_f = PI_f * 2.0f
+    private const val DEGREES_TO_RADIANS: Double = 0.017453292519943295
+
+    fun fma(a: Float, b: Float, c: Float): Float {
+        return a * b + c
+    }
+
+    fun cosFromSin(sin: Float, angle: Float): Float {
+        // sin(x)^2 + cos(x)^2 = 1
+        val cos: Float = sqrt(1.0f - sin * sin)
+        val a: Float = angle + PI_OVER_2_f
+        var b: Float = a - (a / PI_TIMES_2_f).toInt() * PI_TIMES_2_f
+        if (b < 0.0) b = PI_TIMES_2_f + b
+        if (b >= PI_f) return -cos
+        return cos
+    }
+
+    fun invsqrt(r: Float): Float {
+        return 1.0f / sqrt(r)
+    }
+
+    fun toRadians(angdeg: Double): Double {
+        return angdeg * DEGREES_TO_RADIANS
+    }
+}