slang-shaders/stereoscopic-3d/shaders/fubax_vr/VR.slang

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#version 450
/*
/// VR shader ///
Make any game VR and any screen with lenses a VR headset.
Thanks to this shader you'll be able to correct distortions of any lens types
(DIY, experimental) and chromatic aberration.
Also if a game outputs depth pass you can have a stereo-3D vision thanks to
the parallax mapping (which needs some further improvement).
Copyright (c) 2019 Jacob Max Fober
This work is licensed under the Creative Commons
Attribution-NonCommercial-ShareAlike 4.0 International License.
To view a copy of this license, visit
http://creativecommons.org/licenses/by-nc-sa/4.0/
If you want to use it commercially, contact me at jakub.m.fober@pm.me
If you have questions, visit https://reshade.me/forum/shader-discussion/
I'm author of most of equations present here,
beside Brown-Conrady distortion correction model and
Parallax Steep and Occlusion mapping which
I changed and adopted from various sources.
Version 0.4.2 alpha
*/
layout(push_constant) uniform Push
{
vec4 SourceSize;
vec4 OutputSize;
uint FrameCount;
} params;
#include "fubax_vr_params.inc"
#pragma stage vertex
layout(location = 0) in vec4 Position;
layout(location = 1) in vec2 TexCoord;
layout(location = 0) out vec2 texcoord;
void main()
{
gl_Position = global.MVP * Position;
texcoord = TexCoord * 1.00001;
}
#pragma stage fragment
layout(location = 0) in vec2 texcoord;
layout(location = 0) out vec4 FragColor;
layout(set = 0, binding = 2) uniform sampler2D Source;
#include "fubax_vr_shared_funcs.inc"
void main()
{
// Get display aspect ratio (horizontal/vertical resolution)
const float rAspect = params.OutputSize.x*params.OutputSize.w;
// Divide screen in two
vec2 UvCoord = StereoSwitch? StereoVision(texcoord, IPD) : texcoord;
// Generate negative-positive stereo mask
float StereoMask = step(0.5, texcoord.x)*2.0-1.0;
// Correct lens distortion
if(PerspectiveSwitch)
{
// Center coordinates
UvCoord = UvCoord*2.0-1.0;
UvCoord.x *= rAspect;
vec2 StereoCoord = UvCoord; // Save coordinates for Brown-Conrady correction
// Base distortion correction
if(bool(FOV)) // If FOV is not equal 0
{
float radFOV = radians(FOV);
// Calculate radius
float Radius = length(UvCoord);
// Apply base lens correction
switch(LensType)
{
case 0:
{ UvCoord *= Orthographic(radFOV, Radius); break; }
case 1:
{ UvCoord *= Equisolid(radFOV, Radius); break; }
case 2:
{ UvCoord *= Equidistant(radFOV, Radius); break; }
case 3:
{ UvCoord *= Stereographic(radFOV, Radius); break; }
}
};
// Lens geometric aberration correction (Brown-Conrady model)
float Diagonal = rAspect;
Diagonal *= StereoSwitch ? 0.5 : 1.0;
Diagonal = length(vec2(Diagonal, 1.0));
float InvDiagonal2 = 1.0 / pow(Diagonal, 2);
StereoCoord /= Diagonal; // Normalize diagonally
float Radius2 = dot(StereoCoord, StereoCoord); // Squared radius
float correctionK = kRadial(Radius2, K.x, K.y, K.z, K.w);
// Apply negative-positive stereo mask for tangental distortion (flip side)
float SideScreenSwitch = (StereoSwitch) ? StereoMask : 1.0;
vec2 correctionP = pTangental(
StereoCoord,
Radius2,
P.x * SideScreenSwitch,
P.y,
P.z,
0.0
);
// Expand background to vertical border (but not for test grid for ease of calibration)
UvCoord /= TestGrid ? vec2(1.0) : vec2(kRadial(InvDiagonal2, K.x, K.y, K.z, K.w));
UvCoord = UvCoord * correctionK + correctionP; // Apply lens correction
// Scale image
UvCoord /= TestGrid ? vec2(1.0) : vec2(ImageScale);
// Revert aspect ratio to square
UvCoord.x /= rAspect;
// Move origin back to left top corner
UvCoord = UvCoord*0.5 + vec2(0.5);
}
// Display test grid
if(TestGrid) {
FragColor = vec4(Grid(UvCoord, rAspect), 1.0);
return;
}
/* Disable for RetroArch since there's no depth buffer
// Create parallax effect
if(ParallaxSwitch)
{
float ParallaxDirection = ParallaxOffset*0.01;
// For stereo-vison flip direction on one side
ParallaxDirection *= StereoSwitch ? StereoMask : 1.0;
// Apply parallax effect
UvCoord = Parallax(
UvCoord,
ParallaxDirection,
ParallaxCenter,
ParallaxMaskScalar,
ParallaxSteps
);
}
*/
// added by hunterk to adjust aspect ratio of the image
vec2 corrected_size = params.SourceSize.xy * vec2(img_ar.x / img_ar.y, 1.0)
* vec2(params.SourceSize.y / params.SourceSize.x, 1.0);
float full_scale = params.OutputSize.y / params.SourceSize.y;
vec2 scale = (params.OutputSize.xy / corrected_size) / full_scale;
vec2 middle = vec2(0.49999, 0.49999);
vec2 diff = UvCoord.xy - middle;
vec2 screen_coord = middle + diff * scale;
UvCoord = ((screen_coord - vec2(0.5)) * imgzoom) + vec2(0.5);
// Sample image with black borders to display
vec3 Image = mix(
texture(Source, UvCoord).rgb, // Display image
vec3(0.0), // Black borders
BorderMaskAA(UvCoord) // Anti-aliased border mask
);
// Display image
FragColor = vec4(Image, 1.0);
}