Quick'n'Dirty Ray Intersect Sphere

float intersectRaySphere(Ray ray,Sphere sphere) {
	Vec dst = ray.o - sphere.o;
	Real B = dot(dst,ray.d);
	Real C = dot(dst,dst) - sphere.r2;
	Real D = B*B - C;
	return D > 0 ? - B - sqrt(D) : std::numeric_limits<float>::infinity();
}

i bet there is a typo

btw, an ARB_fragment_program version of this function is actually used in this pic

here's the ARB_fragment_program implementing a ray-sphere test

!!ARBfp1.0 #rayTracer Sphere1 
TEMP origin;
TEMP direction;
PARAM sphere = { 0.0,0.0,2.0,1.0 };
TEX origin, fragment.texcoord[0], texture[0], RECT;
TEX direction, fragment.texcoord[0], texture[1], RECT;
# intersectRaySphere 
TEMP distance;
SUB distance,origin,sphere;
# quadricEquation 
TEMP params;
DP3 params.x,distance,direction;
DP3 params.y,distance,distance;
SUB params.y,params.y,sphere.w;
MAD params.z,params.x,params.x,-params.y;
KIL params.z;
RSQ params.z,params.z;
RCP params.z,params.z;
ADD params.x,-params.x,-params.z;
TEMP point;
MAD point,params.x,direction,origin;
TEMP normal;
SUB normal,point,sphere;
DP3 normal.w,normal,normal;
RSQ normal.w,normal.w;
MUL normal,normal,normal.w;
TEMP diffuse;
DP3 diffuse,normal,state.light[0].position;
PARAM color = { 1.0,0.5,0.25,0 };
MUL result.depth,params.x,0.125;
MUL result.color,color,diffuse;
END

wow, very nice piece of code. very useful.

Nice picture. Thank for the Code!

just be warned, it does only hit the outer hull (or so.., the near one)..

call it glEnable(GL_SPHERE_INSIDE_CULLING_RT);

wow... it's so majestic.

[star wars "the force" theme solo on horn plays in my head]

hehe, thanks..

the death star never looked that round, did it?

could you resize the pic down? it's painfully large .

however, you do appreciate it's smoothness at this size...

i could post the software version.. runs at the same speed as the hw version, but on 320x240