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-   -   How to render a texture of the transparent object and then blur it (https://forum.worldviz.com/showthread.php?t=2732)

whj 05-12-2010 04:16 PM

How to render a texture of the transparent object and then blur it
 
Hi,

I would like to have an object in Vizard that simulates blurred glass (glossy refraction) with varying degrees of blur. At low or zero blur, the object would be transparent, and at high blur it would be very blurry. I want the object to render such that if the object moves, whatever is behind the object is blurred.

I've tried to create a render texture and render node attached to the transparent object, and then apply a blur shader to the texture. I put some sample code provided by worldviz together, but can't seem to get it to behave appropriately. I've included it below. Is this the right approach or is there a better way?

Thanks in advance!

Code:

import viz
viz.go()

# add objects
viz.add('gallery.ive')

target = viz.add( 'box.wrl' )
target.setScale(1,1,0.001)
target.setPosition(0,2,1)
target.color(0.5,0.5,0.5)

# make it tranparent
target.alpha(0.4)


# shader programming
kernel = 50
size = 512

#Uniforms for shaders
srcImageUniform = viz.addUniformInt('srcImage',0)
blurScaleUniform = viz.addUniformFloat('blurScale',1.0)

blur_source = """
uniform sampler2D srcImage;
uniform float blurScale;
void main(void)
{
        vec4 color = vec4(0,0,0,0);
        %code%
        color.a = 1.0;
        gl_FragColor = color;
}"""
               
#Calculate weight and offsets for blur code
weights = []
offsets = []
mid = float(kernel - 1)
kernel *= 2
for i in xrange(0,kernel,2):
        offsets.append( ((i-mid) / 2.0) * (1.0 / size) )
        x = (i - mid) / mid
        weights.append( 0.05 + ((-(x*x) + 1.0) / 4.0) )
                       
#Normalize weights
total = sum(weights)
frac = 1.0 / total
weights = [ frac * x for x in weights]

#Create blur code for shaders
horz_blur_code = []
vert_blur_code = []
for w,o in zip(weights,offsets):
        horz_blur_code.append('color += ( texture2D( srcImage, gl_TexCoord[0].xy + vec2( %f*blurScale, 0.0 ) ) * %f );'%(o,w))
        vert_blur_code.append('color += ( texture2D( srcImage, gl_TexCoord[0].xy + vec2( 0.0, %f*blurScale ) ) * %f );'%(o,w))
                       
horzBlurShader = viz.addShader(frag=blur_source.replace('%code%','\n'.join( horz_blur_code ) ))
vertBlurShader = viz.addShader(frag=blur_source.replace('%code%','\n'.join( vert_blur_code ) ))


# apply shader on texture
for eye in [viz.RENDER_LEFT,viz.RENDER_RIGHT]:
                       
        #Render textures for ping-ponging
        tex1 = viz.addRenderTexture()
        tex2 = viz.addRenderTexture()
                       
        """
        Pass 1 renders the normal scene to a texture
        """
        pass1 = viz.addRenderNode(size=[size,size])
        pass1.attachTexture(tex1)
        pass1.setOrder(viz.PRE_RENDER,-5)
        pass1.disable(eye)
                       
        """
        Pass 2 renders the texture from pass 1 onto a quad.
        The quad has a shader attached which blurs the texture horizontally.
        """
        pass2 = viz.addRenderNode()
        pass2.setHUD(0,200,0,200,renderQuad=True)
        pass2.setSize(size,size)
        pass2.setBuffer(viz.RENDER_FBO)
        pass2.setOrder(viz.PRE_RENDER,-4)
        pass2.attachTexture(tex2)
        pass2.texture(tex1)
        pass2.apply(horzBlurShader)
        pass2.apply(srcImageUniform)
        pass2.apply(blurScaleUniform)
        pass2.disable(eye)
                       
        """
        Pass 3 renders the texture from pass 2 onto a quad.
        The quad has a shader attached which blurs the texture vertically.
        """
        pass3 = viz.addRenderNode()
        pass3.setHUD(0,200,0,200,renderQuad=True)
        pass3.setSize(size,size)
        pass3.setBuffer(viz.RENDER_FBO)
        pass3.setOrder(viz.PRE_RENDER,-3)
        pass3.attachTexture(tex1)
        pass3.texture(tex2)
        pass3.apply(vertBlurShader)
        pass3.apply(srcImageUniform)
        pass3.apply(blurScaleUniform)
        pass3.disable(eye)
                       
        """
        Pass 4 renders the final blurred texture to the screen
        """
        pass4 = viz.addRenderNode()
        pass4.setHUD(0,200,0,200,renderQuad=True)
        pass4.setOrder(viz.POST_RENDER,-1)
        pass4.texture(tex1)
        pass4.disable(eye)
                       
        #Save render nodes and blur uniform
        #d.passes += [pass1,pass2,pass3,pass4]
                       

# apply shader       
target.apply(horzBlurShader)
target.apply(vertBlurShader)
target.apply(srcImageUniform)
target.apply(blurScaleUniform)


jde 09-25-2012 03:15 PM

We're trying to accomplish the same thing. Any luck with this issue?


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