GPU Off-Screen Buffer (gpu.offscreen)
This module provides access to offscreen rendering functions.
# Draws an off-screen buffer and display it in the corner of the view.
import bpy
from bgl import *
class OffScreenDraw(bpy.types.Operator):
bl_idname = "view3d.offscreen_draw"
bl_label = "View3D Offscreen Draw"
_handle_calc = None
_handle_draw = None
is_enabled = False
# manage draw handler
@staticmethod
def draw_callback_px(self, context):
scene = context.scene
aspect_ratio = scene.render.resolution_x / scene.render.resolution_y
self._update_offscreen(context, self._offscreen)
self._opengl_draw(context, self._texture, aspect_ratio, 0.2)
@staticmethod
def handle_add(self, context):
OffScreenDraw._handle_draw = bpy.types.SpaceView3D.draw_handler_add(
self.draw_callback_px, (self, context),
'WINDOW', 'POST_PIXEL',
)
@staticmethod
def handle_remove():
if OffScreenDraw._handle_draw is not None:
bpy.types.SpaceView3D.draw_handler_remove(OffScreenDraw._handle_draw, 'WINDOW')
OffScreenDraw._handle_draw = None
# off-screen buffer
@staticmethod
def _setup_offscreen(context):
import gpu
scene = context.scene
aspect_ratio = scene.render.resolution_x / scene.render.resolution_y
try:
offscreen = gpu.offscreen.new(512, int(512 / aspect_ratio))
except Exception as e:
print(e)
offscreen = None
return offscreen
@staticmethod
def _update_offscreen(context, offscreen):
scene = context.scene
render = scene.render
camera = scene.camera
modelview_matrix = camera.matrix_world.inverted()
projection_matrix = camera.calc_matrix_camera(
render.resolution_x,
render.resolution_y,
render.pixel_aspect_x,
render.pixel_aspect_y,
)
offscreen.draw_view3d(
scene,
context.space_data,
context.region,
projection_matrix,
modelview_matrix,
)
@staticmethod
def _opengl_draw(context, texture, aspect_ratio, scale):
"""
OpenGL code to draw a rectangle in the viewport
"""
glDisable(GL_DEPTH_TEST)
# view setup
glMatrixMode(GL_PROJECTION)
glPushMatrix()
glLoadIdentity()
glMatrixMode(GL_MODELVIEW)
glPushMatrix()
glLoadIdentity()
glOrtho(-1, 1, -1, 1, -15, 15)
gluLookAt(0.0, 0.0, 1.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0)
act_tex = Buffer(GL_INT, 1)
glGetIntegerv(GL_TEXTURE_2D, act_tex)
viewport = Buffer(GL_INT, 4)
glGetIntegerv(GL_VIEWPORT, viewport)
width = int(scale * viewport[2])
height = int(width / aspect_ratio)
glViewport(viewport[0], viewport[1], width, height)
glScissor(viewport[0], viewport[1], width, height)
# draw routine
glEnable(GL_TEXTURE_2D)
glActiveTexture(GL_TEXTURE0)
glBindTexture(GL_TEXTURE_2D, texture)
texco = [(1, 1), (0, 1), (0, 0), (1, 0)]
verco = [(1.0, 1.0), (-1.0, 1.0), (-1.0, -1.0), (1.0, -1.0)]
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL)
glColor4f(1.0, 1.0, 1.0, 1.0)
glBegin(GL_QUADS)
for i in range(4):
glTexCoord3f(texco[i][0], texco[i][1], 0.0)
glVertex2f(verco[i][0], verco[i][1])
glEnd()
# restoring settings
glBindTexture(GL_TEXTURE_2D, act_tex[0])
glDisable(GL_TEXTURE_2D)
# reset view
glMatrixMode(GL_PROJECTION)
glPopMatrix()
glMatrixMode(GL_MODELVIEW)
glPopMatrix()
glViewport(viewport[0], viewport[1], viewport[2], viewport[3])
glScissor(viewport[0], viewport[1], viewport[2], viewport[3])
# operator functions
@classmethod
def poll(cls, context):
return context.area.type == 'VIEW_3D'
def modal(self, context, event):
if context.area:
context.area.tag_redraw()
return {'PASS_THROUGH'}
def invoke(self, context, event):
if OffScreenDraw.is_enabled:
self.cancel(context)
return {'FINISHED'}
else:
self._offscreen = OffScreenDraw._setup_offscreen(context)
if self._offscreen:
self._texture = self._offscreen.color_texture
else:
self.report({'ERROR'}, "Error initializing offscreen buffer. More details in the console")
return {'CANCELLED'}
OffScreenDraw.handle_add(self, context)
OffScreenDraw.is_enabled = True
if context.area:
context.area.tag_redraw()
context.window_manager.modal_handler_add(self)
return {'RUNNING_MODAL'}
def cancel(self, context):
OffScreenDraw.handle_remove()
OffScreenDraw.is_enabled = False
if context.area:
context.area.tag_redraw()
def register():
bpy.utils.register_class(OffScreenDraw)
def unregister():
bpy.utils.unregister_class(OffScreenDraw)
if __name__ == "__main__":
register()
new(width, height, samples=0)
Return a GPUOffScreen.
- param width
Horizontal dimension of the buffer.
- type width
int`
- param height
Vertical dimension of the buffer.
- type height
int`
- param samples
OpenGL samples to use for MSAA or zero to disable.
- type samples
int
- return
Newly created off-screen buffer.
- rtype
gpu.GPUOffscreen
- class gpu.offscreen.GPUOffscreen
- This object gives access to off screen buffers.
bind(save=True)
Bind the offscreen object.
- param save
save OpenGL current states.
- type save
bool
draw_view3d(scene, view3d, region, modelview_matrix, projection_matrix)
Draw the 3d viewport in the offscreen object.
- param scene
Scene to draw.
- type scene
bpy.types.Scene- param view3d
3D View to get the drawing settings from.
- type view3d
bpy.types.SpaceView3D- param region
Region of the 3D View.
- type region
bpy.types.Region- param modelview_matrix
ModelView Matrix.
- type modelview_matrix
- param projection_matrix
Projection Matrix.
- type projection_matrix
free()
Free the offscreen object The framebuffer, texture and render objects will no longer be accessible.
unbind(restore=True)
Unbind the offscreen object.
- param restore
restore OpenGL previous states.
- type restore
bool
- color_texture
Color texture.
- Type
int
- height
Texture height.
- Type
int
- width
Texture width.
- Type
int