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Fragment shader for Oculus Rift distortion in GStreamer glshader
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#extension GL_ARB_texture_rectangle : enable | |
uniform sampler2DRect bgl_RenderedTexture; | |
const vec4 kappa = vec4(1.0,1.7,0.7,15.0); | |
const float screen_width = 1920.0; | |
const float screen_height = 1080.0; | |
const float scaleFactor = 0.9; | |
const vec2 leftCenter = vec2(0.25, 0.5); | |
const vec2 rightCenter = vec2(0.75, 0.5); | |
const float separation = -0.05; | |
// Scales input texture coordinates for distortion. | |
vec2 hmdWarp(vec2 LensCenter, vec2 texCoord, vec2 Scale, vec2 ScaleIn) { | |
vec2 theta = (texCoord - LensCenter) * ScaleIn; | |
float rSq = theta.x * theta.x + theta.y * theta.y; | |
vec2 rvector = theta * (kappa.x + kappa.y * rSq + kappa.z * rSq * rSq + kappa.w * rSq * rSq * rSq); | |
vec2 tc = LensCenter + Scale * rvector; | |
return tc; | |
} | |
bool validate(vec2 tc, int left_eye) { | |
//keep within bounds of texture | |
if ((left_eye == 1 && (tc.x < 0.0 || tc.x > 0.5)) || | |
(left_eye == 0 && (tc.x < 0.5 || tc.x > 1.0)) || | |
tc.y < 0.0 || tc.y > 1.0) { | |
return false; | |
} | |
return true; | |
} | |
void main() { | |
vec2 screen = vec2(screen_width, screen_height); | |
float as = float(screen.x / 2.0) / float(screen.y); | |
vec2 Scale = vec2(0.5, as); | |
vec2 ScaleIn = vec2(2.0 * scaleFactor, 1.0 / as * scaleFactor); | |
vec2 texCoord = (gl_TexCoord[0].st / screen); | |
vec2 texCoordSeparated = texCoord; | |
vec2 tc = vec2(0); | |
vec4 color = vec4(0); | |
if (texCoord.x < 0.5) { | |
texCoordSeparated.x += separation; | |
tc = hmdWarp(leftCenter, texCoordSeparated, Scale, ScaleIn ); | |
color = texture2DRect(bgl_RenderedTexture, tc * screen); | |
if (!validate(tc, 1)) | |
color = vec4(0); | |
} else { | |
texCoordSeparated.x -= separation; | |
tc = hmdWarp(rightCenter, texCoordSeparated, Scale, ScaleIn); | |
color = texture2DRect(bgl_RenderedTexture, tc * screen); | |
if (!validate(tc, 0)) | |
color = vec4(0); | |
} | |
gl_FragColor = color; | |
} |
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