mirror of
https://github.com/ZDoom/gzdoom-gles.git
synced 2024-11-25 13:41:05 +00:00
58 lines
1.8 KiB
GLSL
58 lines
1.8 KiB
GLSL
/*
|
|
Original Lens Distortion Algorithm from SSontech
|
|
http://www.ssontech.com/content/lensalg.htm
|
|
|
|
If (u,v) are the coordinates of a feature in the undistorted perfect
|
|
image plane, then (u', v') are the coordinates of the feature on the
|
|
distorted image plate, ie the scanned or captured image from the
|
|
camera. The distortion occurs radially away from the image center,
|
|
with correction for the image aspect ratio (image_aspect = physical
|
|
image width/height), as follows:
|
|
|
|
r2 = image_aspect*image_aspect*u*u + v*v
|
|
f = 1 + r2*(k + kcube*sqrt(r2))
|
|
u' = f*u
|
|
v' = f*v
|
|
|
|
The constant k is the distortion coefficient that appears on the lens
|
|
panel and through Sizzle. It is generally a small positive or negative
|
|
number under 1%. The constant kcube is the cubic distortion value found
|
|
on the image preprocessor's lens panel: it can be used to undistort or
|
|
redistort images, but it does not affect or get computed by the solver.
|
|
When no cubic distortion is needed, neither is the square root, saving
|
|
time.
|
|
|
|
Chromatic Aberration example,
|
|
using red distord channel with green and blue undistord channel:
|
|
|
|
k = vec3(-0.15, 0.0, 0.0);
|
|
kcube = vec3(0.15, 0.0, 0.0);
|
|
*/
|
|
|
|
in vec2 TexCoord;
|
|
out vec4 FragColor;
|
|
|
|
uniform sampler2D InputTexture;
|
|
uniform float Aspect; // image width/height
|
|
uniform float Scale; // 1/max(f)
|
|
uniform vec4 k; // lens distortion coefficient
|
|
uniform vec4 kcube; // cubic distortion value
|
|
|
|
void main()
|
|
{
|
|
vec2 position = (TexCoord - vec2(0.5));
|
|
|
|
vec2 p = vec2(position.x * Aspect, position.y);
|
|
float r2 = dot(p, p);
|
|
vec3 f = vec3(1.0) + r2 * (k.rgb + kcube.rgb * sqrt(r2));
|
|
|
|
vec3 x = f * position.x * Scale + 0.5;
|
|
vec3 y = f * position.y * Scale + 0.5;
|
|
|
|
vec3 c;
|
|
c.r = texture(InputTexture, vec2(x.r, y.r)).r;
|
|
c.g = texture(InputTexture, vec2(x.g, y.g)).g;
|
|
c.b = texture(InputTexture, vec2(x.b, y.b)).b;
|
|
|
|
FragColor = vec4(c, 1.0);
|
|
}
|