remove ui namespace which is not really used, move CameraData in camera_modes.h to avoid the inclusion of canva.h

src/brush.h

@@ -2,8 +2,6 @@
 #include "rtt.h"
 #include "shader.h"
 
-NS_START
-
 class Brush
 {
 public:
@@ -89,7 +87,7 @@ public:
     float m_dist = 0;
     float m_step = 0;
     Camera m_camera;
-    ui::Brush m_brush;
+    Brush m_brush;
     cbuffer<float, 3> m_curve_angles;
     cbuffer<float, 10> m_pressure_buff;
     cbuffer<glm::vec3, 3> m_hsv_jitter;
@@ -99,12 +97,10 @@ public:
     std::vector<StrokeSample> m_samples;
     int m_last_kp;
     std::minstd_rand prng;
-    void start(const ui::Brush& brush);
+    void start(const Brush& brush);
     void add_point(glm::vec3 pos, float pressure);
     void reset(bool clear_keypoints = false);
     bool has_sample();
     std::vector<StrokeSample> compute_samples();
     StrokeSample randomize_sample(const glm::vec3& pos, float pressure, float curve_angle);
 };
-
-NS_END