render.py

# ##### BEGIN GPL LICENSE BLOCK #####
#
#  This program is free software; you can redistribute it and/or
#  modify it under the terms of the GNU General Public License
#  as published by the Free Software Foundation; either version 2
#  of the License, or (at your option) any later version.
#
#  This program is distributed in the hope that it will be useful,
#  but WITHOUT ANY WARRANTY; without even the implied warranty of
#  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#  GNU General Public License for more details.
#
#  You should have received a copy of the GNU General Public License
#  along with this program; if not, write to the Free Software Foundation,
#  Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
#
# ##### END GPL LICENSE BLOCK #####

import bpy
import subprocess
import os
import sys
import time
import math

import platform as pltfrm
if pltfrm.architecture()[0] == '64bit':
    bitness = 64
else:
    bitness = 32


def write_pov(filename, scene=None, info_callback=None):
    file = open(filename, 'w')

    # Only for testing
    if not scene:
        scene = bpy.data.scenes[0]

    render = scene.render
    world = scene.world

    def uniqueName(name, nameSeq):

        if name not in nameSeq:
            return name

        name_orig = name
        i = 1
        while name in nameSeq:
            name = '%s_%.3d' % (name_orig, i)
            i += 1

        return name

    def writeMatrix(matrix):
        file.write('\tmatrix <%.6f, %.6f, %.6f,  %.6f, %.6f, %.6f,  %.6f, %.6f, %.6f,  %.6f, %.6f, %.6f>\n' %\
        (matrix[0][0], matrix[0][1], matrix[0][2], matrix[1][0], matrix[1][1], matrix[1][2], matrix[2][0], matrix[2][1], matrix[2][2], matrix[3][0], matrix[3][1], matrix[3][2]))

    def writeObjectMaterial(material):
        if material and material.transparency_method == 'RAYTRACE':
            file.write('\tinterior { ior %.6f }\n' % material.raytrace_transparency.ior)

            # Other interior args
            # fade_distance 2
            # fade_power [Value]
            # fade_color

            # dispersion
            # dispersion_samples

    materialNames = {}
    DEF_MAT_NAME = 'Default'

    def writeMaterial(material):
        # Assumes only called once on each material

        if material:
            name_orig = material.name
        else:
            name_orig = DEF_MAT_NAME

        name = materialNames[name_orig] = uniqueName(bpy.utils.clean_name(name_orig), materialNames)

        file.write('#declare %s = finish {\n' % name)

        if material:
            file.write('\tdiffuse %.3g\n' % material.diffuse_intensity)
            file.write('\tspecular %.3g\n' % material.specular_intensity)

            file.write('\tambient %.3g\n' % material.ambient)
            #file.write('\tambient rgb <%.3g, %.3g, %.3g>\n' % tuple([c*material.ambient for c in world.ambient_color])) # povray blends the global value

            # map hardness between 0.0 and 1.0
            roughness = ((1.0 - ((material.specular_hardness - 1.0) / 510.0)))
            # scale from 0.0 to 0.1
            roughness *= 0.1
            # add a small value because 0.0 is invalid
            roughness += (1 / 511.0)

            file.write('\troughness %.3g\n' % roughness)

            # 'phong 70.0 '

            if material.raytrace_mirror.enabled:
                raytrace_mirror = material.raytrace_mirror
                if raytrace_mirror.reflect_factor:
                    file.write('\treflection {\n')
                    file.write('\t\trgb <%.3g, %.3g, %.3g>' % tuple(material.mirror_color))
                    file.write('\t\tfresnel 1 falloff %.3g exponent %.3g metallic %.3g} ' % (raytrace_mirror.fresnel, raytrace_mirror.fresnel_factor, raytrace_mirror.reflect_factor))

        else:
            file.write('\tdiffuse 0.8\n')
            file.write('\tspecular 0.2\n')


        # This is written into the object
        '''
        if material and material.transparency_method=='RAYTRACE':
            'interior { ior %.3g} ' % material.raytrace_transparency.ior
        '''

        #file.write('\t\t\tcrand 1.0\n') # Sand granyness
        #file.write('\t\t\tmetallic %.6f\n' % material.spec)
        #file.write('\t\t\tphong %.6f\n' % material.spec)
        #file.write('\t\t\tphong_size %.6f\n' % material.spec)
        #file.write('\t\t\tbrilliance %.6f ' % (material.specular_hardness/256.0) # Like hardness

        file.write('}\n')

    def exportCamera():
        camera = scene.camera
        matrix = camera.matrix_world

        # compute resolution
        Qsize = float(render.resolution_x) / float(render.resolution_y)

        file.write('camera {\n')
        file.write('\tlocation  <0, 0, 0>\n')
        file.write('\tlook_at  <0, 0, -1>\n')
        file.write('\tright <%s, 0, 0>\n' % - Qsize)
        file.write('\tup <0, 1, 0>\n')
        file.write('\tangle  %f \n' % (360.0 * math.atan(16.0 / camera.data.lens) / math.pi))

        file.write('\trotate  <%.6f, %.6f, %.6f>\n' % tuple([math.degrees(e) for e in matrix.rotation_part().to_euler()]))
        file.write('\ttranslate <%.6f, %.6f, %.6f>\n' % (matrix[3][0], matrix[3][1], matrix[3][2]))
        file.write('}\n')

    def exportLamps(lamps):
        # Get all lamps
        for ob in lamps:
            lamp = ob.data

            matrix = ob.matrix_world

            color = tuple([c * lamp.energy for c in lamp.color]) # Colour is modified by energy

            file.write('light_source {\n')
            file.write('\t< 0,0,0 >\n')
            file.write('\tcolor rgb<%.3g, %.3g, %.3g>\n' % color)

            if lamp.type == 'POINT': # Point Lamp
                pass
            elif lamp.type == 'SPOT': # Spot
                file.write('\tspotlight\n')

                # Falloff is the main radius from the centre line
                file.write('\tfalloff %.2f\n' % (degrees(lamp.spot_size) / 2.0)) # 1 TO 179 FOR BOTH
                file.write('\tradius %.6f\n' % ((degrees(lamp.spot_size) / 2.0) * (1.0 - lamp.spot_blend)))

                # Blender does not have a tightness equivilent, 0 is most like blender default.
                file.write('\ttightness 0\n') # 0:10f

                file.write('\tpoint_at  <0, 0, -1>\n')
            elif lamp.type == 'SUN':
                file.write('\tparallel\n')
                file.write('\tpoint_at  <0, 0, -1>\n') # *must* be after 'parallel'

            elif lamp.type == 'AREA':

                size_x = lamp.size
                samples_x = lamp.shadow_ray_samples_x
                if lamp.shape == 'SQUARE':
                    size_y = size_x
                    samples_y = samples_x
                else:
                    size_y = lamp.size_y
                    samples_y = lamp.shadow_ray_samples_y

                file.write('\tarea_light <%d,0,0>,<0,0,%d> %d, %d\n' % (size_x, size_y, samples_x, samples_y))
                if lamp.shadow_ray_sampling_method == 'CONSTANT_JITTERED':
                    if lamp.jitter:
                        file.write('\tjitter\n')
                else:
                    file.write('\tadaptive 1\n')
                    file.write('\tjitter\n')

            if lamp.shadow_method == 'NOSHADOW':
                file.write('\tshadowless\n')

            file.write('\tfade_distance %.6f\n' % lamp.distance)
            file.write('\tfade_power %d\n' % 1) # Could use blenders lamp quad?
            writeMatrix(matrix)

            file.write('}\n')

    def exportMeta(metas):

        # TODO - blenders 'motherball' naming is not supported.

        for ob in metas:
            meta = ob.data

            file.write('blob {\n')
            file.write('\t\tthreshold %.4g\n' % meta.threshold)

            try:
                material = meta.materials[0] # lame! - blender cant do enything else.
            except:
                material = None

            for elem in meta.elements:

                if elem.type not in ('BALL', 'ELLIPSOID'):
                    continue # Not supported

                loc = elem.location

                stiffness = elem.stiffness
                if elem.negative:
                    stiffness = - stiffness

                if elem.type == 'BALL':

                    file.write('\tsphere { <%.6g, %.6g, %.6g>, %.4g, %.4g ' % (loc.x, loc.y, loc.z, elem.radius, stiffness))

                    # After this wecould do something simple like...
                    # 	"pigment {Blue} }"
                    # except we'll write the color

                elif elem.type == 'ELLIPSOID':
                    # location is modified by scale
                    file.write('\tsphere { <%.6g, %.6g, %.6g>, %.4g, %.4g ' % (loc.x / elem.size_x, loc.y / elem.size_y, loc.z / elem.size_z, elem.radius, stiffness))
                    file.write('scale <%.6g, %.6g, %.6g> ' % (elem.size_x, elem.size_y, elem.size_z))

                if material:
                    diffuse_color = material.diffuse_color

                    if material.transparency and material.transparency_method == 'RAYTRACE':
                        trans = 1.0 - material.raytrace_transparency.filter
                    else:
                        trans = 0.0

                    file.write('pigment {rgbft<%.3g, %.3g, %.3g, %.3g, %.3g>} finish {%s} }\n' % \
                        (diffuse_color[0], diffuse_color[1], diffuse_color[2], 1.0 - material.alpha, trans, materialNames[material.name]))

                else:
                    file.write('pigment {rgb<1 1 1>} finish {%s} }\n' % DEF_MAT_NAME)		# Write the finish last.

            writeObjectMaterial(material)

            writeMatrix(ob.matrix_world)

            file.write('}\n')

    def exportMeshs(scene, sel):

        ob_num = 0

        for ob in sel:
            ob_num += 1

            if ob.type in ('LAMP', 'CAMERA', 'EMPTY', 'META', 'ARMATURE', 'LATTICE'):
                continue

            me = ob.data
            me_materials = me.materials

            me = ob.create_mesh(scene, True, 'RENDER')

            if not me:
                continue

            if info_callback:
                info_callback('Object %2.d of %2.d (%s)' % (ob_num, len(sel), ob.name))

            #if ob.type!='MESH':
            #	continue
            # me = ob.data

            matrix = ob.matrix_world
            try:
                uv_layer = me.active_uv_texture.data
            except:
                uv_layer = None

            try:
                vcol_layer = me.active_vertex_color.data
            except:
                vcol_layer = None

            faces_verts = [f.verts for f in me.faces]
            faces_normals = [tuple(f.normal) for f in me.faces]
            verts_normals = [tuple(v.normal) for v in me.verts]

            # quads incur an extra face
            quadCount = len([f for f in faces_verts if len(f) == 4])

            file.write('mesh2 {\n')
            file.write('\tvertex_vectors {\n')
            file.write('\t\t%s' % (len(me.verts))) # vert count
            for v in me.verts:
                file.write(',\n\t\t<%.6f, %.6f, %.6f>' % tuple(v.co)) # vert count
            file.write('\n  }\n')


            # Build unique Normal list
            uniqueNormals = {}
            for fi, f in enumerate(me.faces):
                fv = faces_verts[fi]
                # [-1] is a dummy index, use a list so we can modify in place
                if f.smooth: # Use vertex normals
                    for v in fv:
                        key = verts_normals[v]
                        uniqueNormals[key] = [-1]
                else: # Use face normal
                    key = faces_normals[fi]
                    uniqueNormals[key] = [-1]

            file.write('\tnormal_vectors {\n')
            file.write('\t\t%d' % len(uniqueNormals)) # vert count
            idx = 0
            for no, index in uniqueNormals.items():
                file.write(',\n\t\t<%.6f, %.6f, %.6f>' % no) # vert count
                index[0] = idx
                idx += 1
            file.write('\n  }\n')


            # Vertex colours
            vertCols = {} # Use for material colours also.

            if uv_layer:
                # Generate unique UV's
                uniqueUVs = {}

                for fi, uv in enumerate(uv_layer):

                    if len(faces_verts[fi]) == 4:
                        uvs = uv.uv1, uv.uv2, uv.uv3, uv.uv4
                    else:
                        uvs = uv.uv1, uv.uv2, uv.uv3

                    for uv in uvs:
                        uniqueUVs[tuple(uv)] = [-1]

                file.write('\tuv_vectors {\n')
                #print unique_uvs
                file.write('\t\t%s' % (len(uniqueUVs))) # vert count
                idx = 0
                for uv, index in uniqueUVs.items():
                    file.write(',\n\t\t<%.6f, %.6f>' % uv)
                    index[0] = idx
                    idx += 1
                '''
                else:
                    # Just add 1 dummy vector, no real UV's
                    file.write('\t\t1') # vert count
                    file.write(',\n\t\t<0.0, 0.0>')
                '''
                file.write('\n  }\n')


            if me.vertex_colors:

                for fi, f in enumerate(me.faces):
                    material_index = f.material_index
                    material = me_materials[material_index]

                    if material and material.vertex_color_paint:

                        col = vcol_layer[fi]

                        if len(faces_verts[fi]) == 4:
                            cols = col.color1, col.color2, col.color3, col.color4
                        else:
                            cols = col.color1, col.color2, col.color3

                        for col in cols:
                            key = col[0], col[1], col[2], material_index # Material index!
                            vertCols[key] = [-1]

                    else:
                        if material:
                            diffuse_color = tuple(material.diffuse_color)
                            key = diffuse_color[0], diffuse_color[1], diffuse_color[2], material_index
                            vertCols[key] = [-1]


            else:
                # No vertex colours, so write material colours as vertex colours
                for i, material in enumerate(me_materials):

                    if material:
                        diffuse_color = tuple(material.diffuse_color)
                        key = diffuse_color[0], diffuse_color[1], diffuse_color[2], i # i == f.mat
                        vertCols[key] = [-1]


            # Vert Colours
            file.write('\ttexture_list {\n')
            file.write('\t\t%s' % (len(vertCols))) # vert count
            idx = 0
            for col, index in vertCols.items():

                if me_materials:
                    material = me_materials[col[3]]
                    material_finish = materialNames[material.name]

                    if material.transparency and material.transparency_method == 'RAYTRACE':
                        trans = 1.0 - material.raytrace_transparency.filter
                    else:
                        trans = 0.0

                else:
                    material_finish = DEF_MAT_NAME # not working properly,
                    trans = 0.0

                #print material.apl
                file.write(',\n\t\ttexture { pigment {rgbft<%.3g, %.3g, %.3g, %.3g, %.3g>} finish {%s}}' %
                            (col[0], col[1], col[2], 1.0 - material.alpha, trans, material_finish))

                index[0] = idx
                idx += 1

            file.write('\n  }\n')

            # Face indicies
            file.write('\tface_indices {\n')
            file.write('\t\t%d' % (len(me.faces) + quadCount)) # faces count
            for fi, f in enumerate(me.faces):
                fv = faces_verts[fi]
                material_index = f.material_index
                if len(fv) == 4:
                    indicies = (0, 1, 2), (0, 2, 3)
                else:
                    indicies = ((0, 1, 2),)

                if vcol_layer:
                    col = vcol_layer[fi]

                    if len(fv) == 4:
                        cols = col.color1, col.color2, col.color3, col.color4
                    else:
                        cols = col.color1, col.color2, col.color3


                if not me_materials or me_materials[material_index] == None: # No materials
                    for i1, i2, i3 in indicies:
                        file.write(',\n\t\t<%d,%d,%d>' % (fv[i1], fv[i2], fv[i3])) # vert count
                else:
                    material = me_materials[material_index]
                    for i1, i2, i3 in indicies:
                        if me.vertex_colors and material.vertex_color_paint:
                            # Colour per vertex - vertex colour

                            col1 = cols[i1]
                            col2 = cols[i2]
                            col3 = cols[i3]

                            ci1 = vertCols[col1[0], col1[1], col1[2], material_index][0]
                            ci2 = vertCols[col2[0], col2[1], col2[2], material_index][0]
                            ci3 = vertCols[col3[0], col3[1], col3[2], material_index][0]
                        else:
                            # Colour per material - flat material colour
                            diffuse_color = material.diffuse_color
                            ci1 = ci2 = ci3 = vertCols[diffuse_color[0], diffuse_color[1], diffuse_color[2], f.material_index][0]

                        file.write(',\n\t\t<%d,%d,%d>, %d,%d,%d' % (fv[i1], fv[i2], fv[i3], ci1, ci2, ci3)) # vert count


            file.write('\n  }\n')

            # normal_indices indicies
            file.write('\tnormal_indices {\n')
            file.write('\t\t%d' % (len(me.faces) + quadCount)) # faces count
            for fi, fv in enumerate(faces_verts):

                if len(fv) == 4:
                    indicies = (0, 1, 2), (0, 2, 3)
                else:
                    indicies = ((0, 1, 2),)

                for i1, i2, i3 in indicies:
                    if f.smooth:
                        file.write(',\n\t\t<%d,%d,%d>' %\
                        (uniqueNormals[verts_normals[fv[i1]]][0],\
                         uniqueNormals[verts_normals[fv[i2]]][0],\
                         uniqueNormals[verts_normals[fv[i3]]][0])) # vert count
                    else:
                        idx = uniqueNormals[faces_normals[fi]][0]
                        file.write(',\n\t\t<%d,%d,%d>' % (idx, idx, idx)) # vert count

            file.write('\n  }\n')

            if uv_layer:
                file.write('\tuv_indices {\n')
                file.write('\t\t%d' % (len(me.faces) + quadCount)) # faces count
                for fi, fv in enumerate(faces_verts):

                    if len(fv) == 4:
                        indicies = (0, 1, 2), (0, 2, 3)
                    else:
                        indicies = ((0, 1, 2),)

                    uv = uv_layer[fi]
                    if len(faces_verts[fi]) == 4:
                        uvs = tuple(uv.uv1), tuple(uv.uv2), tuple(uv.uv3), tuple(uv.uv4)
                    else:
                        uvs = tuple(uv.uv1), tuple(uv.uv2), tuple(uv.uv3)

                    for i1, i2, i3 in indicies:
                        file.write(',\n\t\t<%d,%d,%d>' %\
                        (uniqueUVs[uvs[i1]][0],\
                         uniqueUVs[uvs[i2]][0],\
                         uniqueUVs[uvs[i2]][0])) # vert count
                file.write('\n  }\n')

            if me.materials:
                material = me.materials[0] # dodgy
                writeObjectMaterial(material)

            writeMatrix(matrix)
            file.write('}\n')

            bpy.data.meshes.remove(me)

    def exportWorld(world):
        if not world:
            return

        mist = world.mist

        if mist.use_mist:
            file.write('fog {\n')
            file.write('\tdistance %.6f\n' % mist.depth)
            file.write('\tcolor rgbt<%.3g, %.3g, %.3g, %.3g>\n' % (tuple(world.horizon_color) + (1 - mist.intensity,)))
            #file.write('\tfog_offset %.6f\n' % mist.start)
            #file.write('\tfog_alt 5\n')
            #file.write('\tturbulence 0.2\n')
            #file.write('\tturb_depth 0.3\n')
            file.write('\tfog_type 1\n')
            file.write('}\n')

    def exportGlobalSettings(scene):

        file.write('global_settings {\n')

        if scene.pov_radio_enable:
            file.write('\tradiosity {\n')
            file.write("\t\tadc_bailout %.4g\n" % scene.pov_radio_adc_bailout)
            file.write("\t\talways_sample %d\n" % scene.pov_radio_always_sample)
            file.write("\t\tbrightness %.4g\n" % scene.pov_radio_brightness)
            file.write("\t\tcount %d\n" % scene.pov_radio_count)
            file.write("\t\terror_bound %.4g\n" % scene.pov_radio_error_bound)
            file.write("\t\tgray_threshold %.4g\n" % scene.pov_radio_gray_threshold)
            file.write("\t\tlow_error_factor %.4g\n" % scene.pov_radio_low_error_factor)
            file.write("\t\tmedia %d\n" % scene.pov_radio_media)
            file.write("\t\tminimum_reuse %.4g\n" % scene.pov_radio_minimum_reuse)
            file.write("\t\tnearest_count %d\n" % scene.pov_radio_nearest_count)
            file.write("\t\tnormal %d\n" % scene.pov_radio_normal)
            file.write("\t\trecursion_limit %d\n" % scene.pov_radio_recursion_limit)
            file.write('\t}\n')

        if world:
            file.write("\tambient_light rgb<%.3g, %.3g, %.3g>\n" % tuple(world.ambient_color))

        file.write('}\n')


    # Convert all materials to strings we can access directly per vertex.
    writeMaterial(None) # default material

    for material in bpy.data.materials:
        writeMaterial(material)

    exportCamera()
    #exportMaterials()
    sel = scene.objects
    exportLamps([l for l in sel if l.type == 'LAMP'])
    exportMeta([l for l in sel if l.type == 'META'])
    exportMeshs(scene, sel)
    exportWorld(scene.world)
    exportGlobalSettings(scene)

    file.close()
    


def write_pov_ini(filename_ini, filename_pov, filename_image):
    scene = bpy.data.scenes[0]
    render = scene.render

    x = int(render.resolution_x * render.resolution_percentage * 0.01)
    y = int(render.resolution_y * render.resolution_percentage * 0.01)

    file = open(filename_ini, 'w')

    file.write('Input_File_Name="%s"\n' % filename_pov)
    file.write('Output_File_Name="%s"\n' % filename_image)

    file.write('Width=%d\n' % x)
    file.write('Height=%d\n' % y)

    # Needed for border render.
    '''
    file.write('Start_Column=%d\n' % part.x)
    file.write('End_Column=%d\n' % (part.x+part.w))

    file.write('Start_Row=%d\n' % (part.y))
    file.write('End_Row=%d\n' % (part.y+part.h))
    '''

    file.write('Display=0\n')
    file.write('Pause_When_Done=0\n')
    file.write('Output_File_Type=T\n') # TGA, best progressive loading
    file.write('Output_Alpha=1\n')

    if render.render_antialiasing:
        aa_mapping = {'5': 2, '8': 3, '11': 4, '16': 5} # method 1 assumed
        file.write('Antialias=1\n')
        file.write('Antialias_Depth=%d\n' % aa_mapping[render.antialiasing_samples])
    else:
        file.write('Antialias=0\n')

    file.close()


class PovrayRender(bpy.types.RenderEngine):
    bl_idname = 'POVRAY_RENDER'
    bl_label = "Povray"
    DELAY = 0.02

    def _export(self, scene):
        import tempfile

        self._temp_file_in = tempfile.mktemp(suffix='.pov')
        self._temp_file_out = tempfile.mktemp(suffix='.tga')
        self._temp_file_ini = tempfile.mktemp(suffix='.ini')
        '''
        self._temp_file_in = '/test.pov'
        self._temp_file_out = '/test.tga'
        self._temp_file_ini = '/test.ini'
        '''

        def info_callback(txt):
            self.update_stats("", "POVRAY: " + txt)

        write_pov(self._temp_file_in, scene, info_callback)

    def _render(self):

        try:
            os.remove(self._temp_file_out) # so as not to load the old file
        except:
            pass

        write_pov_ini(self._temp_file_ini, self._temp_file_in, self._temp_file_out)

        print ("***-STARTING-***")

        pov_binary = "povray"

        if sys.platform == 'win32':
            import winreg
            regKey = winreg.OpenKey(winreg.HKEY_CURRENT_USER, 'Software\\POV-Ray\\v3.6\\Windows')

            if bitness == 64:
                pov_binary = winreg.QueryValueEx(regKey, 'Home')[0] + '\\bin\\pvengine64'
            else:
                pov_binary = winreg.QueryValueEx(regKey, 'Home')[0] + '\\bin\\pvengine'

        if 1:
            # TODO, when povray isnt found this gives a cryptic error, would be nice to be able to detect if it exists
            try:
                self._process = subprocess.Popen([pov_binary, self._temp_file_ini]) # stdout=subprocess.PIPE, stderr=subprocess.PIPE
            except OSError:
                # TODO, report api
                print("POVRAY: could not execute '%s', possibly povray isn't installed" % pov_binary)
                import traceback
                traceback.print_exc()
                print ("***-DONE-***")
                return False

        else:
            # This works too but means we have to wait until its done
            os.system('%s %s' % (pov_binary, self._temp_file_ini))

        print ("***-DONE-***")
        return True

    def _cleanup(self):
        for f in (self._temp_file_in, self._temp_file_ini, self._temp_file_out):
            try:
                os.remove(f)
            except:
                pass

        self.update_stats("", "")

    def render(self, scene):

        self.update_stats("", "POVRAY: Exporting data from Blender")
        self._export(scene)
        self.update_stats("", "POVRAY: Parsing File")

        if not self._render():
            self.update_stats("", "POVRAY: Not found")
            return

        r = scene.render

        # compute resolution
        x = int(r.resolution_x * r.resolution_percentage * 0.01)
        y = int(r.resolution_y * r.resolution_percentage * 0.01)

        # Wait for the file to be created
        while not os.path.exists(self._temp_file_out):
            if self.test_break():
                try:
                    self._process.terminate()
                except:
                    pass
                break

            if self._process.poll() != None:
                self.update_stats("", "POVRAY: Failed")
                break

            time.sleep(self.DELAY)

        if os.path.exists(self._temp_file_out):

            self.update_stats("", "POVRAY: Rendering")

            prev_size = -1

            def update_image():
                result = self.begin_result(0, 0, x, y)
                lay = result.layers[0]
                # possible the image wont load early on.
                try:
                    lay.load_from_file(self._temp_file_out)
                except:
                    pass
                self.end_result(result)

            # Update while povray renders
            while True:

                # test if povray exists
                if self._process.poll() is not None:
                    update_image()
                    break

                # user exit
                if self.test_break():
                    try:
                        self._process.terminate()
                    except:
                        pass

                    break

                # Would be nice to redirect the output
                # stdout_value, stderr_value = self._process.communicate() # locks


                # check if the file updated
                new_size = os.path.getsize(self._temp_file_out)

                if new_size != prev_size:
                    update_image()
                    prev_size = new_size

                time.sleep(self.DELAY)

        self._cleanup()