diff --git a/TODO.md b/TODO.md
index c0864dd..3b4b39d 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,8 +1,5 @@
 
 ## TODO:
-- restructure some entity/render_group stuffs
-	- add interface to render_group for glBindBuffer->glBufferSubData?
-		- hexgrid.cpp then wouldn't need to call gl functions directly
 - init HexGrid render groups in hgInit and remove slCreateHexRenderGroups
 - position entities on grid hexes
 - pathfinding
diff --git a/src/hexgrid.cpp b/src/hexgrid.cpp
index 7dd28fc..4644f23 100644
--- a/src/hexgrid.cpp
+++ b/src/hexgrid.cpp
@@ -97,18 +97,12 @@ hgAddHex(hexgrid& hg, v3f hex_coords, render_group* rg_filled, render_group* rg_
 			populateLineGLBuffers(hg, new_hex, rg_lines);
 
 			// NOTE: we could send just a part of the buffer if performance ends up being bad here
-			glBindBuffer(GL_ARRAY_BUFFER, vb_f.buffer_id);
-			glBufferSubData(GL_ARRAY_BUFFER, 0, vb_f.count * sizeof(GLfloat), vb_f.buffer);
-			glBindBuffer(GL_ARRAY_BUFFER, nb_f.buffer_id);
-			glBufferSubData(GL_ARRAY_BUFFER, 0, nb_f.count * sizeof(GLfloat), nb_f.buffer);
-			glBindBuffer(GL_ARRAY_BUFFER, ub_f.buffer_id);
-			glBufferSubData(GL_ARRAY_BUFFER, 0, ub_f.count * sizeof(GLfloat), ub_f.buffer);
-			glBindBuffer(GL_ARRAY_BUFFER, vb_l.buffer_id);
-			glBufferSubData(GL_ARRAY_BUFFER, 0, vb_l.count * sizeof(GLfloat), vb_l.buffer);
-			glBindBuffer(GL_ARRAY_BUFFER, nb_l.buffer_id);
-			glBufferSubData(GL_ARRAY_BUFFER, 0, nb_l.count * sizeof(GLfloat), nb_l.buffer);
-			glBindBuffer(GL_ARRAY_BUFFER, ub_l.buffer_id);
-			glBufferSubData(GL_ARRAY_BUFFER, 0, ub_l.count * sizeof(GLfloat), ub_l.buffer);
+			rgUpdateGLBuffer(vb_f);
+			rgUpdateGLBuffer(nb_f);
+			rgUpdateGLBuffer(ub_f);
+			rgUpdateGLBuffer(vb_l);
+			rgUpdateGLBuffer(nb_l);
+			rgUpdateGLBuffer(ub_l);
 
 			return true;
 		} else {
@@ -155,18 +149,12 @@ hgRemoveHex(hexgrid& hg, v3f hex_coords, render_group* rg_filled, render_group*
 		}
 
 		// NOTE: we do need to update the whole buffer when removing data
-		glBindBuffer(GL_ARRAY_BUFFER, vb_f.buffer_id);
-		glBufferSubData(GL_ARRAY_BUFFER, 0, vb_f.count * sizeof(GLfloat), vb_f.buffer);
-		glBindBuffer(GL_ARRAY_BUFFER, nb_f.buffer_id);
-		glBufferSubData(GL_ARRAY_BUFFER, 0, nb_f.count * sizeof(GLfloat), nb_f.buffer);
-		glBindBuffer(GL_ARRAY_BUFFER, ub_f.buffer_id);
-		glBufferSubData(GL_ARRAY_BUFFER, 0, ub_f.count * sizeof(GLfloat), ub_f.buffer);
-		glBindBuffer(GL_ARRAY_BUFFER, vb_l.buffer_id);
-		glBufferSubData(GL_ARRAY_BUFFER, 0, vb_l.count * sizeof(GLfloat), vb_l.buffer);
-		glBindBuffer(GL_ARRAY_BUFFER, nb_l.buffer_id);
-		glBufferSubData(GL_ARRAY_BUFFER, 0, nb_l.count * sizeof(GLfloat), nb_l.buffer);
-		glBindBuffer(GL_ARRAY_BUFFER, ub_l.buffer_id);
-		glBufferSubData(GL_ARRAY_BUFFER, 0, ub_l.count * sizeof(GLfloat), ub_l.buffer);
+		rgUpdateGLBuffer(vb_f);
+		rgUpdateGLBuffer(nb_f);
+		rgUpdateGLBuffer(ub_f);
+		rgUpdateGLBuffer(vb_l);
+		rgUpdateGLBuffer(nb_l);
+		rgUpdateGLBuffer(ub_l);
 
 		return true;
 	}
@@ -192,8 +180,7 @@ hgUpdateUVBuffer(hexgrid& hg, render_group* rg)
 		}
 	}
 
-	glBindBuffer(GL_ARRAY_BUFFER, uv_buf.buffer_id);
-	glBufferSubData(GL_ARRAY_BUFFER, 0, uv_buf.count * sizeof(GLfloat), uv_buf.buffer);
+	rgUpdateGLBuffer(uv_buf);
 }
 
 hex_info*
diff --git a/src/render_group.cpp b/src/render_group.cpp
index 76b3118..ff1cd0d 100644
--- a/src/render_group.cpp
+++ b/src/render_group.cpp
@@ -159,6 +159,13 @@ rgInitGLIndexBuffer(gl_index_buffer* index_buffer, GLenum usage, GLenum target)
 	glBufferData(target, index_buffer->count * sizeof(uint), index_buffer->buffer, usage);
 }
 
+void
+rgUpdateGLBuffer(gl_buffer& buffer)
+{
+	glBindBuffer(GL_ARRAY_BUFFER, buffer.buffer_id);
+	glBufferSubData(GL_ARRAY_BUFFER, 0, buffer.count * sizeof(GLfloat), buffer.buffer);
+}
+
 void
 rgDraw(render_group* rg, glm::mat4 model_matrix,
 	glm::mat4 view_matrix, glm::mat4 projection_matrix,
diff --git a/src/render_group.h b/src/render_group.h
index 7cb08d1..d04a368 100644
--- a/src/render_group.h
+++ b/src/render_group.h
@@ -84,6 +84,8 @@ void rgInitGLFloatBuffer(gl_buffer* buffer, GLenum usage, GLenum target);
 
 void rgInitGLIndexBuffer(gl_index_buffer* index_buffer, GLenum usage, GLenum target);
 
+void rgUpdateGLBuffer(gl_buffer& buffer);
+
 void rgDraw(render_group* rg, glm::mat4 model_matrix,
 		glm::mat4 view_matrix, glm::mat4 projection_matrix,
 		rg_point_light* lights, uint num_lights,