GLSL ray-sphere intersection

gistfile1.glsl

float raySphereIntersect(vec3 r0, vec3 rd, vec3 s0, float sr) {
    // - r0: ray origin
    // - rd: normalized ray direction
    // - s0: sphere center
    // - sr: sphere radius
    // - Returns distance from r0 to first intersecion with sphere,
    //   or -1.0 if no intersection.
    float a = dot(rd, rd);
    vec3 s0_r0 = r0 - s0;
    float b = 2.0 * dot(rd, s0_r0);
    float c = dot(s0_r0, s0_r0) - (sr * sr);
    if (b*b - 4.0*a*c < 0.0) {
        return -1.0;
    }
    return (-b - sqrt((b*b) - 4.0*a*c))/(2.0*a);
}

Haha what the hell are you mad about upload your own function

It worked for me just fine.

IT DOESNT FUCKING WORK FUCK YOU

I too hate it when i steal other people's code but I am to stupid to figure out how to actually use it.

Joking aside, I made a small modification to return both intersection points:

vec2 raySphereIntersect(vec3 r0, vec3 rd, vec3 s0, float sr) {
    float a = dot(rd, rd);
    vec3 s0_r0 = r0 - s0;
    float b = 2.0 * dot(rd, s0_r0);
    float c = dot(s0_r0, s0_r0) - (sr * sr);
	float disc = b * b - 4.0 * a* c;
    if (disc < 0.0) {
        return vec2(-1.0, -1.0);
    }else{
		return vec2(-b - sqrt(disc), -b + sqrt(disc)) / (2.0 * a);
	}
}```

IT DOESNT FUCKING WORK FUCK YOU

Literally worked perfectly without any major changes. Imagine being this much of a tool.

Thanks for the snippet OP!

IT DOESNT FUCKING WORK FUCK YOU

Imagine not having the problem solving skills to fix it if it didn't.

Literally worked perfectly without any major changes. Imagine being this much of a tool.

Thanks for the snippet OP!

Looks super cool, I can't wait to try this out

IT DOESNT FUCKING WORK FUCK YOU

M yes, I too hate it when I copy someone's code and I don't even know how to use, so I then go harrass the creator. /s

With that out of the way, the snippet works fine so thank you OP

In your comment it says rd: normalized ray direction, but then you compute dot(rd, rd) which is always one. So either rd should not be normalized or your code is doing unnecessary operations.

lol are we all using this for a shader in unity

lol are we all using this for a shader in unity

Not me, I'm using it for Love2D.