scripted/simpleImageFile.py

#-
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#+

########################################################################
# DESCRIPTION:
#
# Produces a simple image file plug-in.
#
# This plug-in registers a new image file format against file extension ".moo".
# Loading any ".moo" image file will produce a procedurally generated colour
# spectrum including values outside of 0 to 1.
#
# Usage:
#   (1) Run the script:
#
#   import maya.cmds
#   maya.cmds.loadPlugin("simpleImageFile.py")
#   
#   (2) Perform the following:
#       
#       - Create a poly plane.
#       - Assign a shader to it.
#       - Assign a file texture to the shader.
#       - Make a copy of a project/image file and name it test.moo.
#       - Assign the test.moo image to the file texture.
#       - Turn on hardware texturing.
#       - Render the scene.
#
########################################################################

import maya.OpenMaya as OpenMaya
import maya.OpenMayaMPx as OpenMayaMPx
import maya.OpenMayaRender as OpenMayaRender

import sys

kImagePluginName = "spSimpleImageFile"

# Use MGLFunctionTable to make openGL calls
glRenderer = OpenMayaRender.MHardwareRenderer.theRenderer()
glFT = glRenderer.glFunctionTable()

        
# Class definition
class SimpleImageFile(OpenMayaMPx.MPxImageFile):
    
    # init
    def __init__(self):
        OpenMayaMPx.MPxImageFile.__init__(self)
    
    #   
    # DESCRIPTION:
    #   Configure the image characteristics. A real image file
    #   format plugin would extract these values from the image
    #   file header.
    #
    #################################################################
    def open( self, pathname, info ):
        
        if info is not None:
            info.width( 512 )
            info.height( 512 )
            info.channels( 3 )
            info.pixelType( OpenMaya.MImage.kFloat )

            # Only necessary if your format defines a native
            # hardware texture loader
            info.hardwareType( OpenMaya.MImageFileInfo.kHwTexture2D)        
        
    #
    # DESCRIPTION:
    # Load the contents of this image file into an MImage. A real
    # file format plugin would extract the pixel data from the image
    # file here.
    #
    #################################################################
    def load( self, image, idx ):
        width = 512
        height = 512
    
        # Create a floating point image and fill it with
        # a pretty rainbow test image.
        #   
        image.create( width, height, 3, OpenMaya.MImage.kFloat )
        self.populateTestImage( image.floatPixels(), width, height )        
        
    #
    # DESCRIPTION:
    # Load the contents of this image file into an OpenGL texture. A 
    # real file format plugin would extract the pixel data from the 
    # image file here.
    #
    #################################################################
    def glLoad( self, info, imageNumber ):
        w = info.width()
        h = info.height()

        # Create a floating point image and fill it with
        # a pretty rainbow test image.
        #
        image = OpenMaya.MImage()
        image.create( w, h, 3, OpenMaya.MImage.kFloat )
        self.populateTestImage( image.floatPixels(), w, h )
    
        # Now load it into OpenGL as a floating point image
        glFT.glTexImage2D( OpenMayaRender.MGL_TEXTURE_2D, 0, \
            OpenMayaRender.MGL_RGB, w, h, 0, OpenMayaRender.MGL_RGB, \
            OpenMayaRender.MGL_FLOAT, pixelsPtr )


    #
    # DESCRIPTION:
    # Helper method to populate our procedural test image
    #
    #################################################################
    def populateTestImage( self, pixels, w, h ):
        #
        rainbowScale = 4.0
        index = 0
        for y in range( 0, h ):
            g = rainbowScale * y / float(h)         
            for x in range( 0, w ):
                r = rainbowScale * x / float(w)
                OpenMaya.MScriptUtil.setFloatArray( pixels, index, r )
                index+=1
                OpenMaya.MScriptUtil.setFloatArray( pixels, index, g )
                index+=1
                b = rainbowScale * 1.5 - r - g
                OpenMaya.MScriptUtil.setFloatArray( pixels, index, b )
                index+=1
                
# creator
def creator():
    return OpenMayaMPx.asMPxPtr( SimpleImageFile() )    


# initialize plugin
def initializePlugin( mObject ):
    mPlugin = OpenMayaMPx.MFnPlugin(mObject, "Autodesk", "1.0", "Any")  
    #
    extensions = ["moo"]    
    try:
        mPlugin.registerImageFile( kImagePluginName, creator, extensions )
    except:
        sys.stderr.write( "Failed to register image plugin: %s" % kImagePluginName )
        raise
        
# uninitialize plugin
def uninitializePlugin( mObject ):
    mPlugin = OpenMayaMPx.MFnPlugin( mObject )
    try:
        mPlugin.deregisterImageFile( kImagePluginName )
    except:
        sys.stderr.write( "Failed to deregister image: %s" % kImagePluginName )
        raise