36 lines
953 B
Text
36 lines
953 B
Text
|
#version 150 compatibility
|
||
|
|
|
||
|
|
in SphereData {
|
||
|
|
vec2 q_tilde;
|
||
|
|
float inv_e;
|
||
|
|
vec3 nml_e_eye;
|
||
|
|
vec3 nml_v_eye;
|
||
|
|
vec2 zw_e_clip;
|
||
|
|
vec2 zw_v_clip;
|
||
|
|
vec3 v_eye;
|
||
|
|
} Fin;
|
||
|
|
|
||
|
|
bool compute_sphere_intersection(out float depth, out vec3 p_eye, out vec3 n_eye, in bool show_backside = false)
|
||
|
|
{
|
||
|
|
// check for intersection
|
||
|
|
float q_tilde_squared_length = dot(Fin.q_tilde, Fin.q_tilde);
|
||
|
|
if (q_tilde_squared_length > 1.0)
|
||
|
|
return false;
|
||
|
|
|
||
|
|
// compute ray parameter
|
||
|
|
float beta = Fin.inv_e*sqrt(1.0 - q_tilde_squared_length);
|
||
|
|
float lambda = show_backside ? 1.0 / (1.0 - beta) : 1.0 / (1.0 + beta);
|
||
|
|
|
||
|
|
// depth correction
|
||
|
|
vec2 zw = Fin.zw_e_clip + lambda * Fin.zw_v_clip;
|
||
|
|
float z_clip = zw.x / zw.y;
|
||
|
|
depth = 0.5*(z_clip + 1.0); // transform from [-1,1] to [0,1]
|
||
|
|
|
||
|
|
// compute sphere position and normal in eye coordinates
|
||
|
|
p_eye = lambda*Fin.v_eye;
|
||
|
|
n_eye = normalize(Fin.nml_e_eye + lambda * Fin.nml_v_eye);
|
||
|
|
if (show_backside) {
|
||
|
|
n_eye = -n_eye;
|
||
|
|
}
|
||
|
|
return true;
|
||
|
|
}
|