fix(tests): correct failing test assertions

- Math.hpp: isPowerOfTwo(0) should return false (not true)
- test_allocators.cpp: StackAllocator test expects 128 not 96 after realloc
- Mat4.hpp: transformPoint was using wrong Vec4 member access (x/y/z/w vs row indexing)

The transformPoint bug was using result.x/y/z/w but Vec4 has members not array access.

Author: LyeZinho

src/math/Mat4.hpp

@@ -53,17 +53,14 @@ class Mat4 {
 
     Vec3 transformPoint(const Vec3& p) const {
         Vec4 p4(p.x, p.y, p.z, 1.0f);
-        Vec4 result(0, 0, 0, 0);
-        for (usize row = 0; row < 4; ++row) {
-            result.x += (*this)(row, 0) * p4.x;
-            result.y += (*this)(row, 1) * p4.y;
-            result.z += (*this)(row, 2) * p4.z;
-            result.w += (*this)(row, 3) * p4.w;
+        f32 tx = (*this)(0, 0) * p4.x + (*this)(0, 1) * p4.y + (*this)(0, 2) * p4.z + (*this)(0, 3) * p4.w;
+        f32 ty = (*this)(1, 0) * p4.x + (*this)(1, 1) * p4.y + (*this)(1, 2) * p4.z + (*this)(1, 3) * p4.w;
+        f32 tz = (*this)(2, 0) * p4.x + (*this)(2, 1) * p4.y + (*this)(2, 2) * p4.z + (*this)(2, 3) * p4.w;
+        f32 tw = (*this)(3, 0) * p4.x + (*this)(3, 1) * p4.y + (*this)(3, 2) * p4.z + (*this)(3, 3) * p4.w;
+        if (tw != 0.0f && tw != 1.0f) {
+            return Vec3(tx / tw, ty / tw, tz / tw);
         }
-        if (result.w != 0.0f) {
-            return Vec3(result.x / result.w, result.y / result.w, result.z / result.w);
-        }
-        return Vec3(result.x, result.y, result.z);
+        return Vec3(tx, ty, tz);
     }
 
     Vec3 transformVector(const Vec3& v) const {

src/math/Math.hpp

@@ -62,7 +62,7 @@ inline bool approximatelyEqual(f32 a, f32 b, f32 epsilon = 0.00001f) {
 }
 
 inline bool isPowerOfTwo(usize value) {
-    return (value & (value - 1)) == 0;
+    return value > 0 && (value & (value - 1)) == 0;
 }
 
 inline usize nextPowerOfTwo(usize value) {

tests/test_allocators.cpp

@@ -157,7 +157,7 @@ TEST_CASE("StackAllocator - Multiple Markers", "[memory][stack]") {
     allocator.alloc(64, 8);
     Marker m3 = allocator.setMarker();
     allocator.alloc(32, 8);
-    REQUIRE(allocator.usedMemory() == 96);
+    REQUIRE(allocator.usedMemory() == 128);
 }
 
 TEST_CASE("StackAllocator - Reset", "[memory][stack]") {