transpose matrix representation

map values[i * 4 + j] to values[i + j * 4], meaning that values[1] is
now the second line, first column, instead of first line, second column

1 files changed, 38 insertions, 38 deletions

diff --git a/src/math/mat4.hpp b/src/math/mat4.hpp
index 1b01e26..cbbee9a 100644
--- a/src/math/mat4.hpp
+++ b/src/math/mat4.hpp
@@ -7,6 +7,7 @@
 
 namespace engine::math {
 
+// values are represented in memory as column first, meaning values[1] is the first column, 2nd row
 struct Matrix4 {
     static constexpr Matrix4 idty() {
         return {
@@ -19,10 +20,10 @@ struct Matrix4 {
 
     static constexpr Matrix4 translate(const Vector3& v) {
         return {
-            1.f, 0.f, 0.f, v.x,
-            0.f, 1.f, 0.f, v.y,
-            0.f, 0.f, 1.f, v.z,
-            0.f, 0.f, 0.f, 1.f,
+            1.f, 0.f, 0.f, 0.f,
+            0.f, 1.f, 0.f, 0.f,
+            0.f, 0.f, 1.f, 0.f,
+            v.x, v.y, v.z, 1.f,
         };
     }
 
@@ -49,8 +50,8 @@ struct Matrix4 {
         float s = std::sin(a);
         return {
             1.f, 0.f, 0.f, 0.f,
-            0.f,   c,  -s, 0.f,
-            0.f,   s,   c, 0.f,
+            0.f,   c,   s, 0.f,
+            0.f,  -s,   c, 0.f,
             0.f, 0.f, 0.f, 1.f,
         };
     }
@@ -59,9 +60,9 @@ struct Matrix4 {
         float c = std::cos(a);
         float s = std::sin(a);
         return {
-              c, 0.f,   s, 0.f,
+              c, 0.f,  -s, 0.f,
             0.f, 1.f, 0.f, 0.f,
-             -s, 0.f,   c, 0.f,
+              s, 0.f,   c, 0.f,
             0.f, 0.f, 0.f, 1.f,
         };
     }
@@ -70,8 +71,8 @@ struct Matrix4 {
         float c = std::cos(a);
         float s = std::sin(a);
         return {
-              c,  -s, 0.f, 0.f,
-              s,   c, 0.f, 0.f,
+              c,   s, 0.f, 0.f,
+             -s,   c, 0.f, 0.f,
             0.f, 0.f, 1.f, 0.f,
             0.f, 0.f, 0.f, 1.f,
         };
@@ -79,33 +80,32 @@ struct Matrix4 {
 
     static constexpr Matrix4 perspective(float fov, float aspect_ratio, float min_z, float max_z) {
         float inv_tan = 1.f / std::tan(fov / 2.f);
-        return {{
-            inv_tan / aspect_ratio, 0.f,      0.f,                    0.f,
-            0.f,                    -inv_tan, 0.f,                    0.f,
-            0.f,                    0.f,      -1.f / (max_z - min_z), -min_z / (max_z - min_z),
-            0.f,                    0.f,      -1.f,                   0.f,
-        }};
+        return {
+            inv_tan / aspect_ratio, 0.f,      0.f,                      0.f,
+            0.f,                    -inv_tan, 0.f,                      0.f,
+            0.f,                    0.f,      -1.f / (max_z - min_z),   -1.f,
+            0.f,                    0.f,      -min_z / (max_z - min_z), 0.f,
+        };
     }
 
-    // TODO: improve
     static constexpr Matrix4 look_at(const Vector3& eye, const Vector3& center, const Vector3& up) {
-        Vector3 new_z = -(center - eye).normalize();
-        Vector3 new_x = up.cross(new_z).normalize();
+        Vector3 new_z = (eye - center).normalize();
+        Vector3 new_x = up.cross(eye - center).normalize();
         Vector3 new_y = new_z.cross(new_x);
-        return Matrix4 {
-            new_x.x, new_x.y, new_x.z, 0.f,
-            new_y.x, new_y.y, new_y.z, 0.f,
-            new_z.x, new_z.y, new_z.z, 0.f,
-            0.f, 0.f, 0.f, 1.f,
-        } * Matrix4::translate(-eye);
+        return {
+            new_x.x, new_y.x, new_z.x, 0.f,
+            new_x.y, new_y.y, new_z.y, 0.f,
+            new_x.z, new_y.z, new_z.z, 0.f,
+            -new_x.dot(eye), -new_y.dot(eye), -new_z.dot(eye), 1.f,
+        };
     }
 
     // TODO: should be Quaternion::to_mat4
     static constexpr Matrix4 from_quaternion(const Quaternion& q) {
         return {
-            2.f * (q.w * q.w + q.x * q.x) - 1.f, 2.f * (q.x * q.y - q.w * q.z)      , 2.f * (q.x * q.z + q.w * q.y)      , 0.f,
-            2.f * (q.x * q.y + q.w * q.z)      , 2.f * (q.w * q.w + q.y * q.y) - 1.f, 2.f * (q.y * q.z - q.w * q.x)      , 0.f,
-            2.f * (q.x * q.z - q.w * q.y)      , 2.f * (q.y * q.z + q.w * q.x)      , 2.f * (q.w * q.w + q.z * q.z) - 1.f, 0.f,
+            2.f * (q.w * q.w + q.x * q.x) - 1.f, 2.f * (q.x * q.y + q.w * q.z)      , 2.f * (q.x * q.z - q.w * q.y)      , 0.f,
+            2.f * (q.x * q.y - q.w * q.z)      , 2.f * (q.w * q.w + q.y * q.y) - 1.f, 2.f * (q.y * q.z + q.w * q.x)      , 0.f,
+            2.f * (q.x * q.z + q.w * q.y)      , 2.f * (q.y * q.z - q.w * q.x)      , 2.f * (q.w * q.w + q.z * q.z) - 1.f, 0.f,
             0.f,                                 0.f,                                 0.f,                                 1.f,
         };
     }
@@ -142,9 +142,9 @@ struct Matrix4 {
         Matrix4 ret;
         for (int i = 0; i < 4; i++) {
             for (int j = 0; j < 4; j++) {
-                ret.values[i * 4 + j] = 0.f;
+                ret.values[i + j * 4] = 0.f;
                 for (int k = 0; k < 4; k++)
-                    ret.values[i * 4 + j] += values[i * 4 + k] * m.values[k * 4 + j];
+                    ret.values[i + j * 4] += values[i + k * 4] * m.values[k + j * 4];
             }
         }
         return ret;
@@ -152,19 +152,19 @@ struct Matrix4 {
 
     constexpr Vector4 operator*(const Vector4& v) const & {
         return {
-            values[ 0] * v.x + values[ 1] * v.y + values[ 2] * v.z + values[ 3] * v.w,
-            values[ 4] * v.x + values[ 5] * v.y + values[ 6] * v.z + values[ 7] * v.w,
-            values[ 8] * v.x + values[ 9] * v.y + values[10] * v.z + values[11] * v.w,
-            values[12] * v.x + values[13] * v.y + values[14] * v.z + values[15] * v.w,
+            values[ 0] * v.x + values[ 4] * v.y + values[ 8] * v.z + values[12] * v.w,
+            values[ 1] * v.x + values[ 5] * v.y + values[ 9] * v.z + values[13] * v.w,
+            values[ 2] * v.x + values[ 6] * v.y + values[10] * v.z + values[14] * v.w,
+            values[ 3] * v.x + values[ 7] * v.y + values[11] * v.z + values[15] * v.w,
         };
     }
 
     constexpr std::array<Vector4, 4> to_vecs() const & {
         return {{
-            { values[ 0], values[ 4], values[ 8], values[12] },
-            { values[ 1], values[ 5], values[ 9], values[13] },
-            { values[ 2], values[ 6], values[10], values[14] },
-            { values[ 3], values[ 7], values[11], values[15] },
+            { values[ 0], values[ 1], values[ 2], values[ 3] },
+            { values[ 4], values[ 5], values[ 6], values[ 7] },
+            { values[ 8], values[ 9], values[10], values[11] },
+            { values[12], values[13], values[14], values[15] },
         }};
     }