added uniform buffers, small tweaks

- fixed aspect ratio being the inverse of what it's supposed to be
- use std::chrono::high_resolution_clock instead of system_clock
- convert ellapsed time to float representing seconds
- renamed engine::math::Matrix4::projection to perspective
- use [0,1] instead of [-1,1] for the range of z values, to be aligned
  with vulkan
- added engine::math::Matrix4::{look_at,transpose}

1 files changed, 25 insertions, 3 deletions

diff --git a/src/math/mat4.hpp b/src/math/mat4.hpp
index dfc5a75..1b01e26 100644
--- a/src/math/mat4.hpp
+++ b/src/math/mat4.hpp
@@ -77,16 +77,29 @@ struct Matrix4 {
         };
     }
 
-    static constexpr Matrix4 projection(float fov, float aspect_ratio, float min_z, float max_z) {
+    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 {{
-            aspect_ratio * inv_tan, 0.f,      0.f,                    0.f,
+            inv_tan / aspect_ratio, 0.f,      0.f,                    0.f,
             0.f,                    -inv_tan, 0.f,                    0.f,
-            0.f,                    0.f,      -2.f / (max_z - min_z), -(max_z + min_z) / (max_z - min_z),
+            0.f,                    0.f,      -1.f / (max_z - min_z), -min_z / (max_z - min_z),
             0.f,                    0.f,      -1.f,                   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_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);
+    }
+
     // TODO: should be Quaternion::to_mat4
     static constexpr Matrix4 from_quaternion(const Quaternion& q) {
         return {
@@ -154,6 +167,15 @@ struct Matrix4 {
             { values[ 3], values[ 7], values[11], values[15] },
         }};
     }
+
+    constexpr Matrix4 transpose() 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],
+        };
+    }
 };
 
 constexpr Matrix4 operator*(float fac, const Matrix4& m) {