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#version 330 core
layout(location = 0) in vec3 position; // Position of the vertex
layout(location = 1) in vec3 normal; // Normal of the vertex
layout(location = 2) in vec3 texCoords; // Normal of the vertex
uniform float depth = -1000.f;
uniform float skyHeight = 500.f;
uniform sampler2D normSamp;
out vec3 normal_worldSpace;
out vec3 pos;
out vec3 newPos;
out vec4 col;
out float refractProb;
vec4 refractToFloor(vec3 l, vec3 p, vec3 n, float d) {
// Refracts incoming light direction l through normal n at point p until hits floor at depth d
vec3 w_o = normalize(l);
float cos_theta_i = dot(-w_o, n);
float n_i = 1;
float n_t = 1.33f;
float determinant = 1.f - (pow((n_i / n_t), 2.f) * (1.f - pow(cos_theta_i, 2.f)));
float r0 = pow((n_i - n_t) / (n_i + n_t), 2.f); // variable required to calculate probability of reflection
float prob_to_refl = r0 + ((1 - r0) * pow((1 - cos_theta_i), 5.f));
if (determinant >= 0) {
float cos_theta_t = sqrt(determinant);
vec3 w_t = (n_i / n_t) * w_o + ((n_i / n_t) * cos_theta_i - cos_theta_t) * n;
float dist = p.z - d;
float depthScale = dist / w_t.z;
// vec3 groundContactPoint = -(w_t * depthScale) + p;
vec3 groundContactPoint = (w_t * depthScale) + p;
return vec4(groundContactPoint, 1.f - prob_to_refl);
} else {
return vec4(0, 0, 0, 0);
}
}
void main() {
normal_worldSpace = normal;
pos = position;
vec4 sampledNormal = texture(normSamp, vec2((pos + 1) / 2));
sampledNormal = (sampledNormal * 2.f) - 1.f;
col = sampledNormal;
vec4 newPosAndProb = refractToFloor(vec3(0, 0, 1), pos, normalize(vec3(sampledNormal)), 0.005f);
newPos = vec3(newPosAndProb[0], newPosAndProb[1], 0.f);
refractProb = newPosAndProb[3];
// newPos = pos;
gl_Position = vec4(newPos, 1.f);
}
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