toggle ui with Tab, add hsv jitter

engine/brush.h

@@ -26,11 +26,15 @@ public:
     float m_jitter_angle = 0;
     float m_jitter_spread = 0;
     float m_jitter_flow = 0;
+    float m_jitter_hue = 0;
+    float m_jitter_sat = 0;
+    float m_jitter_val = 0;
     int m_blend_mode = 0;
 };
 
 struct StrokeSample
 {
+    glm::vec3 col = { 0, 0, 0 };
     glm::vec2 pos = { 0, 0 };
     glm::vec2 origin = { 0,0 };
     float size = 0;