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typedef float2 vec2;
typedef float3 vec3;
typedef float4 vec4;
#define sin native_sin
#define cos native_cos
#define tan native_tan
#define normalize fast_normalize
#define length fast_length
#define mod fmod
#define time 1.f
vec3 reflect(vec3 I, vec3 N) {
return I - 2.0f * dot(N, I) * N;
}
uint pack_fp4(float4 u4) {
uint u;
u = (((uint) u4.x)) |
(((uint) u4.y) << 8) |
(((uint) u4.z) << 16);
return u;
}
#define OUTPUT do {\
const vec4 final = 255.f * max(min(gl_FragColor, (vec4)(1.f)), (vec4)(0.f)); \
dst[get_global_id(0) + get_global_id(1) * w] = pack_fp4(final); \
} while (0)
float jinteresct(vec3 rO, vec3 rD, vec4 c, float *ao)
{
float mz2,md2,dist,t;
float res=1000.0f;
vec4 z,nz;
int update_ao = 1;
*ao = 0.0f;
for(t=0.0f;t<6.0f;t+=dist)
{
if (update_ao) *ao += 1.0f;
vec3 p=rO+t*rD;
// calc distance
z=(vec4)(p,(c.y+c.x)*.3f);
md2=1.0f;
mz2=dot(z,z);
for(int i=0;i<9;i++)
{
// |dz|^2 -> 4*|dz|^2
//if (mz2 <= 4.0f)
{
md2*=4.0f*mz2;
// z -> z2 + c
nz.x=z.x*z.x-dot(z.yzw,z.yzw);
nz.yzw=2.0f*z.x*z.yzw;
z=nz+c;
mz2=dot(z,z);
}
if(mz2>4.0f)
break;
}
dist=0.25f*sqrt(mz2/md2)*log(mz2);
if(dist<0.0005f)
{
res=t;
break;
}
t+= dist;
}
return res;
}
#if 1
vec3 calcNormal(vec3 p, vec4 c)
{
vec4 nz,ndz,dz[4];
vec4 z=(vec4)(p,(c.y+c.x)*.3f);
dz[0]=(vec4)(1.0f,0.0f,0.0f,0.0f);
dz[1]=(vec4)(0.0f,1.0f,0.0f,0.0f);
dz[2]=(vec4)(0.0f,0.0f,1.0f,0.0f);
//dz[3]=(vec4)(0.0f,0.0f,0.0f,1.0f);
for(int i=0;i<9;i++)
{
vec4 mz = (vec4)(z.x,-z.y,-z.z,-z.w);
// derivative
dz[0]=(vec4)(dot(mz,dz[0]),z.x*dz[0].yzw+dz[0].x*z.yzw);
dz[1]=(vec4)(dot(mz,dz[1]),z.x*dz[1].yzw+dz[1].x*z.yzw);
dz[2]=(vec4)(dot(mz,dz[2]),z.x*dz[2].yzw+dz[2].x*z.yzw);
//dz[3]=(vec4)(dot(mz,dz[3]),z.x*dz[3].yzw+dz[3].x*z.yzw);
// z = z2 + c
nz.x=dot(z, mz);
nz.yzw=2.0f*z.x*z.yzw;
z=nz+c;
if(dot(z,z)>4.0f)
break;
}
return normalize((vec3)(dot(z,dz[0]),dot(z,dz[1]),dot(z,dz[2])));
}
#endif
__kernel void compiler_julia(__global uint *dst, float resx, float resy, int w)
{
vec2 gl_FragCoord = (vec2)(get_global_id(0), get_global_id(1));
vec2 p=-1.0f+2.0f*gl_FragCoord.xy/(vec2)(resx,resy);
vec3 color = (vec3)(0.0f);
vec4 cccc = (vec4)( .7f*cos(.5f*time), .7f*sin(.3f*time), .7f*cos(1.0f*time), 0.0f );
vec3 edir = normalize((vec3)(p,1.0f));
vec3 wori = (vec3)(0.0f,0.0f,-2.0f);
float ao;
float t = jinteresct(wori,edir,cccc,&ao);
if(t<100.0f)
{
#if 1
vec3 inter = wori + t*edir;
vec3 nor = calcNormal(inter,cccc);
float dif = .5f + .5f*dot( nor, (vec3)(0.57703f) );
ao = max( 1.0f-ao*0.005f, 0.0f);
color = (vec3)(1.0f,.9f,.5f)*dif*ao + .5f*(vec3)(.6f,.7f,.8f)*ao;
#else
color = (vec3)(0.5f,0.0f,0.0f);
#endif
}
else
{
color = (vec3)(0.5f,0.51f,0.52f)+(vec3)(0.5f,0.47f,0.45f)*p.y;
}
vec4 gl_FragColor = (vec4)(color,1.0f);
OUTPUT;
}
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