crt-distort-coordinates

Do a barrel distortion to a given texture coordinate to emulate a curved CRT screen.

Index

Functions

ApproxAtan2

                float2 ApproxAtan2(
                  float2 y, 
                  float2 x)
              

Description

Do a fast approximation of a two-component atan2 calculation. This is only accurate near 0 (it only uses a few terms from its taylor series, so becomes increasingly inaccurate away from the origin. But it is good enough for our purposes.

Called by DistortCRTCoordinates.

Parameters

y

Type: float2

The y component(s) of the angle (corresponding to the sine of the angle(s)).

x

Type: float2

The x component(s) of the angle (corresponding to the cosine of the output angle(s)).

Return Value

Type: float2

A pair of angles, one for each y, x pair of inputs.

DistortCRTCoordinates

                float2 DistortCRTCoordinates(
                  float2 texCoord,
                  float2 distortion)              
              

Description

Do a barrel distortion to a given texture coordinate to emulate a curved CRT screen.

Called by generate-screen-texture and rgb-to-crt.

Parameters

texCoord

Type: float2

The original texture coordinate, intended to come straight from the full-render-target quad, in [-1..1] range (not standard [0..1])

distortion

Type: float2

A (horizontal, vertical) distortion pair which describes the effective curvature of the virtual screen.

Return Value

Type: float2

The texture coordinates, distorted to emulate being on a curved screen.