diff --git a/client/src/hex.c b/client/src/hex.c
index 86df12f..55069dc 100644
--- a/client/src/hex.c
+++ b/client/src/hex.c
@@ -895,7 +895,14 @@ bool ray_hex_intersect(
     float intersect_distance = glm_vec3_dot(v0v2, q) / det;
     if(intersect_distance < *distance) {
       *distance = intersect_distance;
-      *vertex = (u > v) ? ((triangle+1) % 6)+1 : triangle+1;
+      float w = 1 - u - v;
+      if(u >= v && u >= w) {
+        *vertex = ((triangle + 1) % 6) + 1;
+      } else if(v >= u && v >= w) {
+        *vertex = triangle + 1;
+      } else {
+        *vertex = 0;
+      }
     }
   }
 
diff --git a/client/src/main.c b/client/src/main.c
index ef917e5..9837402 100644
--- a/client/src/main.c
+++ b/client/src/main.c
@@ -16,14 +16,23 @@
 #include <math.h>
 #include <stdlib.h>
 
-typedef struct EditorContextStruct { 
+typedef struct EditorDataStruct { 
   uint32_t selected_region;
   uint32_t last_selected_region;
 
   uint32_t last_clicked_region;
   uint32_t last_clicked_hex;
   uint32_t last_clicked_vertex;
-} EditorContext;
+} EditorData;
+
+#define COLOR_PICK_CONTAINER_ID 0x03
+typedef struct ColorUIDataStruct {
+  double current_hsv[3];
+  vec4 current;
+  vec4 saved[12];
+  char string[10];
+  int string_len;
+} ColorUIData;
 
 typedef struct ClientContextStruct {
   GLFWwindow* window;
@@ -48,7 +57,8 @@ typedef struct ClientContextStruct {
   float   zoom_speed;
   float   move_speed;
 
-  EditorContext editor;
+  EditorData editor;
+  ColorUIData color;
 } ClientContext;
 
 void* network_thread(void* data) {
@@ -58,6 +68,11 @@ void* network_thread(void* data) {
   return NULL;
 }
 
+uint32_t hex_color(vec4 color) {
+  // TODO: implement vec4 -> uint32 color conversion
+  return 0x0000000;
+}
+
 uint32_t add_hex_region(ClientContext* context) {
   HexRegion* region;
 
@@ -92,15 +107,6 @@ uint32_t add_hex_region(ClientContext* context) {
   return i;
 }
 
-#define COLOR_PICK_CONTAINER_ID 0x03
-typedef struct ColorUIDataStruct {
-  double current_hsv[3];
-  vec4 current;
-  vec4 saved[12];
-  char string[10];
-  int string_len;
-} ColorUIData;
-
 void update_hex_string(UIContext* ui, RenderContext* gpu, ColorUIData* data) {
   snprintf(data->string, 10, "#%02X%02X%02X%02X",
       (uint)rintf(data->current[0]*255),
@@ -607,7 +613,7 @@ VkResult color_ui(ClientContext* context) {
     .num_drawables = sizeof(drawables)/sizeof(GPUDrawable),
   };
 
-  ColorUIData* data = malloc(sizeof(ColorUIData));
+  ColorUIData* data = &context->color;
   data->string_len = 8;
   data->string[0] = '#';
   data->string[1] = '0';
@@ -1382,6 +1388,26 @@ void key_callback(GLFWwindow* window, int key, int scancode, int action, int mod
         }
       }
       break;
+
+    case GLFW_KEY_E:
+      if(action == GLFW_PRESS) {
+        HexRegion* region = context->hex->regions[context->hex->data.clicked_region];
+        if(region != NULL) {
+          region->data.hexes[context->hex->data.clicked_hex].color[context->hex->data.clicked_vertex] = hex_color(context->color.current); 
+          add_transfer(
+              &region->data.hexes[context->hex->data.clicked_hex].color[context->hex->data.clicked_vertex],
+              region->region,
+              offsetof(GPUHexRegion, hexes)
+              + sizeof(GPUHex)*context->hex->data.clicked_hex
+              + offsetof(GPUHex, color)
+              + sizeof(uint32_t)*(context->hex->data.clicked_vertex),
+              sizeof(uint32_t),
+              context->render->current_frame,
+              context->render);
+          update_hex_info_ui(context);
+        }
+      }
+      break;
   }
 }