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uniform sampler2D bgl_RenderedTexture;
uniform float bgl_RenderedTextureWidth;
uniform float bgl_RenderedTextureHeight;
const vec4 kappa = vec4(1.0,0.7,1.0,1.0);
float screen_width = bgl_RenderedTextureWidth;
float screen_height = bgl_RenderedTextureHeight;
const float scaleFactor = 0.85;
const vec2 leftCenter = vec2(0.25, 0.5);
const vec2 rightCenter = vec2(0.75, 0.5);
const float separation = -0.00;
// Scales input texture coordinates for distortion.
vec2 hmdWarp(vec2 LensCenter, vec2 texCoord, vec2 Scale, vec2 ScaleIn, float eta) {
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 * eta * 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);
vec3 eta = vec3(1.00,1.018,1.042); //refraction indices
float as = float(screen.x / 2.0) / float(screen.y);
vec2 Scale = vec2(0.47, as);
vec2 ScaleIn = vec2(2.0 * scaleFactor, 1.0 / as * scaleFactor);
vec2 texCoord = (gl_TexCoord[0].st);
vec2 texCoordSeparated = texCoord;
vec2 tcR = vec2(0.0);
vec2 tcG = vec2(0.0);
vec2 tcB = vec2(0.0);
vec4 color = vec4(0.0);
if (texCoord.x < 0.5) {
texCoordSeparated.x += separation;
tcR = hmdWarp(leftCenter, texCoordSeparated, Scale, ScaleIn, eta.r );
tcG = hmdWarp(leftCenter, texCoordSeparated, Scale, ScaleIn, eta.g );
tcB = hmdWarp(leftCenter, texCoordSeparated, Scale, ScaleIn, eta.b );
color.r = texture2D(bgl_RenderedTexture, tcR).r;
color.g = texture2D(bgl_RenderedTexture, tcG).g;
color.b = texture2D(bgl_RenderedTexture, tcB).b;
if (!validate(tcR, 1))
color = vec4(0.0);
} else {
texCoordSeparated.x -= separation;
tcR = hmdWarp(rightCenter, texCoordSeparated, Scale, ScaleIn, eta.r );
tcG = hmdWarp(rightCenter, texCoordSeparated, Scale, ScaleIn, eta.g );
tcB = hmdWarp(rightCenter, texCoordSeparated, Scale, ScaleIn, eta.b );
color.r = texture2D(bgl_RenderedTexture, tcR).r;
color.g = texture2D(bgl_RenderedTexture, tcG).g;
color.b = texture2D(bgl_RenderedTexture, tcB).b;
if (!validate(tcR, 0))
color = vec4(0.0);
}
gl_FragColor = color;
}