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Re: [Help]Linear Interpolation of Three Values
I'm guessing you meant that last bit to be "A:0.0 = B"? If not, replace color.b in this code with 0. Something like this should work... float a = color.a * 2; float r = lerp (color.b, color.g, a); a -= 1; r = lerp (r, color.r, a); You could branch it... but I suspect lerping is easier on the shader. They still don't really… -
Re: [Help]Linear Interpolation of Three Values
I'm trying to understand something. In Cg or HLSL the Lerp function does not clamp the parameter value used to interpolate, so when the alpha value is 0.0 the result will be surprising. When alpha is zero: a = 0.0 * 2 x = lerp( B, G, a ) // x = B a -= 1 // a = -1 x = lerp( x, R, a ) // This is x*(1-a) + R*a // x is now 2*B… -
Re: [Help]Linear Interpolation of Three Values
Oh right, yeah. You'll want saturate(a), rather than a inside the lerp then. Can't do clamp outside when defining a otherwise you're clamping a value that needs to span a range of 2. float a = color.a * 2;float r = lerp (color.b, color.g, saturate(a));a -= 1;r = lerp (r, color.r, saturate(a)); -
[Help]Linear Interpolation of Three Values
I'm working on a shader that would use the Alpha to distinguish which RGB channel of a texture to display. My thoughts on how this would work are; A:1.0 = R, A:0.5 = G, A:0.0 = B, Is it possible to build this using Linear Interpolation nodes? If not what would be the correct approach? I'm working with the Strumpy Shader… -
Re: [Help]Linear Interpolation of Three Values
@Farfarer Thanks that worked perfectly, I did some research after I posted and realized the Step Node is A<=B, which was exactly what I needed. Also I corrected the original post. -
Re: [Help]Linear Interpolation of Three Values
Kryzon that's a great reference, I'll definitely be reading more into it. The saturation worked great but I now need to toy with the >.5 end of the spectrum. -
Re: [Help]Linear Interpolation of Three Values
Here is an untested alternative that avoids branching, using the fact that a boolean value can be cast to numeric values in Cg or HLSL. const float a = color.a;float rR = color.r * (float)( a >= 0.66 && a <= 1.0 );float rG = color.g * (float)( a > 0.33 && a < 0.66 );float rB = color.b * (float)( a >= 0.0 && a <= 0.33 );//… -
Re: [Help]Linear Interpolation of Three Values
I understand what you mean. Using Saturate\Clamp only when using 'a' (not when setting its value) is what works. Saturate is a quick way to write Clamp( value, 0.0, 1.0 ). It clamps a value to the range [0, 1]. Saturate is part of the "intrinsic functions" of the shading language. You can find the documentation (the… -
Re: [Help]Linear Interpolation of Three Values
Thanks for the continued help guys! I am unfamiliar with what Saturate does, I looked through both the UDK and Shaderforge Node guides and can only seem to find Desaturate. Would this work the same way if I inverted the product? -
Re: [Help]Linear Interpolation of Three Values
edit: nevermind.
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