[Bf-blender-cvs] [a389636] framebuffer: GPU python code example

[Dalai Felinto]

Commit: a38963657e914a651e0c8a6e76062aca5603eab1
Author: Dalai Felinto
Date:   Mon Oct 19 16:34:43 2015 -0200
Branches: framebuffer
https://developer.blender.org/rBa38963657e914a651e0c8a6e76062aca5603eab1

GPU python code example

===================================================================

A	doc/python_api/examples/gpu.offscreen.1.py

===================================================================

diff --git a/doc/python_api/examples/gpu.offscreen.1.py b/doc/python_api/examples/gpu.offscreen.1.py
new file mode 100644
index 0000000..8e7f223
--- /dev/null
+++ b/doc/python_api/examples/gpu.offscreen.1.py
@@ -0,0 +1,172 @@
+import bpy
+from bgl import *
+
+class VIEW3D_OT_OffScreenDraw(bpy.types.Operator):
+    """"""
+    bl_idname = "view3d.offscreen_draw"
+    bl_label = "Offscreen Draw"
+
+    _handle_calc = None
+    _handle_draw = None
+    is_enabled = False
+
+    @classmethod
+    def poll(cls, context):
+        return context.area.type == 'VIEW_3D'
+
+    @staticmethod
+    def handle_add(self, context):
+        VIEW3D_OT_OffScreenDraw._handle_draw = bpy.types.SpaceView3D.draw_handler_add(
+            self.draw_callback_px, (context, ), 'WINDOW', 'POST_PIXEL')
+
+    @staticmethod
+    def handle_remove():
+        if VIEW3D_OT_OffScreenDraw._handle_draw is not None:
+            bpy.types.SpaceView3D.draw_handler_remove(VIEW3D_OT_OffScreenDraw._handle_draw, 'WINDOW')
+
+        VIEW3D_OT_OffScreenDraw._handle_draw = None
+
+    def modal(self, context, event):
+        if context.area:
+            context.area.tag_redraw()
+
+        return {'PASS_THROUGH'}
+
+    def invoke(self, context, event):
+        if VIEW3D_OT_OffScreenDraw.is_enabled:
+            VIEW3D_OT_OffScreenDraw.handle_remove()
+            VIEW3D_OT_OffScreenDraw.is_enabled = False
+
+            if context.area:
+                context.area.tag_redraw()
+
+            return {'FINISHED'}
+
+        else:
+            if not self.init(context):
+                self.report({'ERROR'}, "Error initializing offscreen buffer. More details in the console")
+                return {'CANCELLED'}
+
+            VIEW3D_OT_OffScreenDraw.handle_add(self, context)
+            VIEW3D_OT_OffScreenDraw.is_enabled = True
+
+            if context.area:
+                context.area.tag_redraw()
+
+            context.window_manager.modal_handler_add(self)
+            return {'RUNNING_MODAL'}
+
+    def init(self, context):
+        import gpu
+        scene = context.scene
+        aspect_ratio = scene.render.resolution_x / scene.render.resolution_y
+
+        try:
+            self._offscreen = gpu.offscreen.new(512, int(512 / aspect_ratio), 0)
+            self._texture = self._offscreen.color_object
+
+        except Exception as E:
+            print(E)
+            return False
+
+        if not self._offscreen:
+            return False
+
+        return True
+
+    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)
+
+    def _update_offscreen(self, context, offscreen):
+        scene = context.scene
+        camera = scene.camera
+
+        modelview_matrix = camera.matrix_world.inverted()
+        projection_matrix = camera.calc_matrix_camera()
+
+        offscreen.draw_view3d(
+                scene,
+                context.space_data,
+                context.region,
+                projection_matrix,
+                modelview_matrix)
+
+    def _opengl_draw(self, 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])
+
+
+def register():
+    bpy.utils.register_class(VIEW3D_OT_OffScreenDraw)
+
+
+def unregister():
+    bpy.utils.unregister_class(VIEW3D_OT_OffScreenDraw)
+
+
+if __name__ == "__main__":
+    register()