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/*
[configuration]
[OptionRangeFloat]
GUIName = Distortion amount
OptionName = DISTORTION_FACTOR
MinValue = 1.0
MaxValue = 10.0
StepAmount = 0.5
DefaultValue = 4.0
[OptionRangeFloat]
GUIName = Eye Distance Offset
OptionName = EYE_OFFSET
MinValue = 0.0
MaxValue = 10.0
StepAmount = 0.25
DefaultValue = 5.0
[OptionRangeFloat]
GUIName = Zoom adjustment
OptionName = SIZE_ADJUST
MinValue = 0.0
MaxValue = 1.0
StepAmount = 0.025
DefaultValue = 0.5
[OptionRangeFloat]
GUIName = Aspect Ratio adjustment
OptionName = ASPECT_ADJUST
MinValue = 0.0
MaxValue = 1.0
StepAmount = 0.025
DefaultValue = 0.5
[/configuration]
*/
void main()
{
// Base Cardboard distortion parameters
float factor = GetOption(DISTORTION_FACTOR) * 0.01f;
float ka = factor * 3.0f;
float kb = factor * 5.0f;
// size and aspect adjustment
float sizeAdjust = 1.0f - GetOption(SIZE_ADJUST) + 0.5f;
float aspectAdjustment = 1.25f - GetOption(ASPECT_ADJUST);
// offset centering per eye
float stereoOffset = GetOption(EYE_OFFSET) * 0.01f;
float offsetAdd;
// layer0 = left eye, layer1 = right eye
if (src_layer == 1)
{
offsetAdd = stereoOffset;
}
else
{
offsetAdd = 0.0 - stereoOffset;
}
// convert coordinates to NDC space
float2 fragPos = (GetCoordinates() - 0.5f - float2(offsetAdd, 0.0f)) * 2.0f;
// Calculate the source location "radius" (distance from the centre of the viewport)
float destR = length(fragPos);
// find the radius multiplier
float srcR = destR * sizeAdjust + ( ka * pow(destR, 2.0) + kb * pow(destR, 4.0));
// Calculate the source vector (radial)
float2 correctedRadial = normalize(fragPos) * srcR;
// fix aspect ratio
float2 widenedRadial = correctedRadial * float2(aspectAdjustment, 1.0f);
// Transform the coordinates (from [-1,1]^2 to [0, 1]^2)
float2 uv = (widenedRadial/2.0f) + float2(0.5f, 0.5f) + float2(offsetAdd, 0.0f);
// Sample the texture at the source location
if (clamp(uv, 0.0, 1.0) != uv)
{
// black if beyond bounds
SetOutput(float4(0.0, 0.0, 0.0, 0.0));
}
else
{
SetOutput(SampleLocation(uv));
}
}
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