Python - 3DView Border Select

Question

I am scripting a plugin in Blender Python (using the newest Blender version, 2.69) and I want to select a region with the Border Select tool in the 3DViewport. I have looked this up in the documentation, and it is extremely confusing.

http://www.blender.org/documentation/blender_python_api_2_69_release/bpy.ops.view3d.html?highlight=select_border#bpy.ops.view3d.select_border

I need an example on how this is supposed to work. Every time I just put the following in my script, it gives this error.

bpy.ops.view3d.select_border(gesture_mode=0, xmin=0, xmax=0, ymin=0, ymax=0, extend=True)

(Note, the large black spots in the picture are where I took out my folder structure ;) )

Thanks in Advance!

Answer 1

The first problem is the context view3d.select_border() should be called inside the 3D_VIEW region, the second problem is the gesture mode which should be 3 for the function to work.

A minimal code example will be :

for area in bpy.context.screen.areas:
    if area.type == 'VIEW_3D':
        override = bpy.context.copy()
        override['area'] = area
        override['region'] = area.regions[4]
        bpy.ops.view3d.select_border(override, gesture_mode=3, xmin=0, xmax=600, ymin=0, ymax=600, extend=True)
        break   

And this is more extended example which implement the border selection tool ( when you press B ) the following script is a modal operator with bgl drawing function to draw the box of selection.

• run the script
• in the 3d view hit Space and type Simple Box
• start selecting by holding the LMB and end selection by releasing it

---

import bpy
import bgl
from mathutils import Vector
from bpy.props import IntProperty, BoolProperty


def draw_callback_px(self, context):

    bgl.glEnable(bgl.GL_BLEND)
    bgl.glColor4f(1.0, 1.0, 1.0, 0.5)
    bgl.glLineWidth(2)

    if self.selecting :
        # when selecting draw dashed line box
        bgl.glEnable(bgl.GL_LINE_STIPPLE)
        bgl.glLineStipple(2, 0x3333)
        bgl.glBegin(bgl.GL_LINE_LOOP)

        bgl.glVertex2i(self.min_x, self.min_y)
        bgl.glVertex2i(self.min_x, self.max_y)
        bgl.glVertex2i(self.max_x, self.max_y)
        bgl.glVertex2i(self.max_x, self.min_y)

        bgl.glEnd()

        bgl.glDisable(bgl.GL_LINE_STIPPLE)
    else :
        # before selection starts draw infinite cross
        bgl.glBegin(bgl.GL_LINES)

        bgl.glVertex2i(0, self.max_y)
        bgl.glVertex2i(context.area.width, self.max_y)        

        bgl.glVertex2i(self.max_x, 0)
        bgl.glVertex2i(self.max_x, context.area.height)

        bgl.glEnd()

    # restore opengl defaults
    bgl.glLineWidth(1)
    bgl.glDisable(bgl.GL_BLEND)
    bgl.glColor4f(0.0, 0.0, 0.0, 1.0)


class SelectOperator(bpy.types.Operator):
    """simple box selection """
    bl_idname = "view3d.box_select"
    bl_label = "Simple Box Select Operator"

    min_x = IntProperty(default = 0)
    min_y = IntProperty(default = 0)
    max_x = IntProperty()
    max_y = IntProperty()

    selecting = BoolProperty(default = False) # just for drawing in bgl

    def modal(self, context, event):
        context.area.tag_redraw()
        if event.type == 'MOUSEMOVE': # just for drawing the box
            self.max_x = event.mouse_region_x
            self.max_y = event.mouse_region_y

        elif event.type == 'LEFTMOUSE':
            if event.value == 'PRESS': # start selection
                self.selecting = True
                self.min_x = event.mouse_region_x
                self.min_y = event.mouse_region_y

            if event.value == 'RELEASE': # end of selection
                #we have to sort the coordinates before passing them to select_border()
                self.max_x = max(event.mouse_region_x, self.min_x)
                self.max_y = max(event.mouse_region_y, self.min_y)
                self.min_x = min(event.mouse_region_x, self.min_x)
                self.min_y = min(event.mouse_region_y, self.min_y)

                bpy.ops.view3d.select_border(gesture_mode=3, xmin=self.min_x, xmax=self.max_x, ymin=self.min_y, ymax=self.max_y, extend=True)
                bpy.types.SpaceView3D.draw_handler_remove(self._handle, 'WINDOW')    
                return {'FINISHED'}

        elif event.type in {'RIGHTMOUSE', 'ESC'}:
            bpy.types.SpaceView3D.draw_handler_remove(self._handle, 'WINDOW')
            return {'CANCELLED'}

        return {'RUNNING_MODAL'}

    def invoke(self, context, event):

        if context.space_data.type == 'VIEW_3D':
            args = (self, context)
            self._handle = bpy.types.SpaceView3D.draw_handler_add(draw_callback_px, args, 'WINDOW', 'POST_PIXEL')
            context.window_manager.modal_handler_add(self)
            return {'RUNNING_MODAL'}
        else:
            self.report({'WARNING'}, "Active space must be a View3d")
            return {'CANCELLED'}


def register():
    bpy.utils.register_class(SelectOperator)


def unregister():
    bpy.utils.unregister_class(SelectOperator)


if __name__ == "__main__":
    register()