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// Oculus DK1 lens distortion shader for multiple eyes
// shader is adapted from Oculus DK1 distortion shader by
// Lubosz Sarnecki(lubosz.wordpress.com/)
uniform sampler2D bgl_RenderedTexture;
uniform float bgl_RenderedTextureWidth;
uniform float bgl_RenderedTextureHeight;
const vec4 kappa = vec4(1.0,1.7,0.7,15.0);
float screen_width = bgl_RenderedTextureWidth;
float screen_height = bgl_RenderedTextureHeight;
const float scaleFactor = 0.8;
const vec2 leftCenter = vec2(0.25, 0.5);
const vec2 rightCenter = vec2(0.75, 0.5);
const float separation = 0.01;
// 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;
vec2 texCoordSeparated = texCoord;
vec2 tc = vec2(0);
vec4 color = vec4(0);
// ad hoc enhanced separation to allow proper viewing factor
float ad_hoc_enhance_stereo = 4.0;
if (texCoord.x < 0.5) {
texCoordSeparated.x -= ad_hoc_enhance_stereo *separation;
tc = hmdWarp(leftCenter, texCoordSeparated, Scale, ScaleIn );
color = texture2D(bgl_RenderedTexture, tc);
if (!validate(tc, 1))
color = vec4(0);
} else {
texCoordSeparated.x += ad_hoc_enhance_stereo *separation;
tc = hmdWarp(rightCenter, texCoordSeparated, Scale, ScaleIn);
color = texture2D(bgl_RenderedTexture, tc);
if (!validate(tc, 0))
color = vec4(0);
}
gl_FragColor = color;
}