Gear.dctl

// Gear DCTL

#define PI		3.1415926536f

typedef struct
{
float t;
float gearR;
float teethH;
float teethR;
float teethCount;
float diskR;
float3 color;
} Gear;

__DEVICE__ Gear make_gear(float A, float B, float C, float D, float E, float F, float3 G)
{
Gear H;
H.t = A;
H.gearR = B;
H.teethH = C;
H.teethR = D;
H.teethCount = E;
H.diskR = F;
H.color = G;
return H;
}

__DEVICE__ float2 add(float2 A, float2 B)
{
float2 C;
C.x = A.x + B.x;
C.y = A.y + B.y;
return C;
}

__DEVICE__ float2 divide(float2 A, float B)
{
float2 C;
C.x = A.x / B;
C.y = A.y / B;
return C;
}

__DEVICE__ float length(float2 A)
{
float B = _sqrtf(A.x * A.x + A.y * A.y);
return B;
}

__DEVICE__ float2 make_float2(float A)
{
return make_float2(A, A);
}

__DEVICE__ float3 make_float3(float A)
{
return make_float3(A, A, A);
}

__DEVICE__ float2 minus(float2 A, float2 B)
{
float2 C;
C.x = A.x - B.x;
C.y = A.y - B.y;
return C;
}

__DEVICE__ float3 mix(float3 A, float3 B, float C)
{
float3 D;
D.x = A.x * (1.0f - C) + B.x * C;
D.y = A.y * (1.0f - C) + B.y * C;
D.z = A.z * (1.0f - C) + B.z * C;
return D;
}

__DEVICE__ float2 multi(float A, float2 B)
{
float2 C;
C.x = A * B.x;
C.y = A * B.y;
return C;
}

__DEVICE__ float3 multi(float3 A, float B)
{
float3 C;
C.x = A.x * B;
C.y = A.y * B;
C.z = A.z * B;
return C;
}

__DEVICE__ float smoothstep(float edge0, float edge1, float x)
{
float t = _saturatef((x - edge0) / (edge1 - edge0));
return t * t * (3.0f - 2.0f * t);
}

__DEVICE__ float GearFunction(float2 uv, Gear g)
{
float r = length(uv);
float a = _atan2f(uv.y, uv.x);
float p = g.gearR - 0.5f * g.teethH + g.teethH / (1.0f + _expf(g.teethR * _sinf(g.t + g.teethCount * a)));
float gear = r - p;
float disk = r - g.diskR;
return g.gearR > g.diskR ? _fmaxf(-disk, gear) : _fmaxf(disk, -gear);
}

__DEVICE__ float GearDe(float2 uv, Gear g)
{
float f = GearFunction(uv, g);
float2 eps = make_float2(0.0001f, 0.0f);
float2 grad = divide(make_float2(
GearFunction(add(uv, eps), g) - GearFunction(minus(uv, eps), g),
GearFunction(add(uv, make_float2(eps.y, eps.x)), g) - GearFunction(minus(uv, make_float2(eps.y, eps.x)), g)), (2.0f * eps.x));
return (f)/length(grad);
}

__DEVICE__ float GearShadow(float2 uv, Gear g)
{
float r = length(add(uv, make_float2(0.1f)));
float de = r - g.diskR + 0.0f * (g.diskR - g.gearR);
float eps = 0.4f * g.diskR;
return smoothstep(eps, 0.0f, _fabs(de));
}

__DEVICE__ void DrawGear(float3 *color, float2 uv, Gear g, float eps)
{
float d = smoothstep(eps, -eps, GearDe(uv, g));
float s = 1.0f - 0.7f * GearShadow(uv, g);
*color = mix(multi(*color, s), g.color, d);
}

__DEVICE__ float3 transform(int p_Width, int p_Height, int p_X, int p_Y, __TEXTURE__ p_TexR, __TEXTURE__ p_TexG, __TEXTURE__ p_TexB)
{
//float iTime = _tex2D(p_TexR, 500, 500) / 24;
float iTime = _tex2D(p_TexR, 500, 500) * 10;

float X = (float)p_X;
float Y = (float)(p_Height - p_Y);
float2 resolution = make_float2((float)p_Width, (float)p_Height);
float t = 0.5f * iTime;
float2 uv;
uv.x = 2.0f * (X - 0.5f * resolution.x) / resolution.y;
uv.y = 2.0f * (Y - 0.5f * resolution.y) / resolution.y;
float eps = 2.0f / resolution.y;

float3 base = make_float3(0.95f, 0.7f, 0.2f);
float count = 8.0f;
Gear outer = make_gear(0.0f, 0.8f, 0.08f, 4.0f, 32.0f, 0.9f, base);
Gear inner = make_gear(0.0f, 0.4f, 0.08f, 4.0f, 16.0f, 0.3f, base);

float3 color = make_float3(0.0f);
for(float i = 0.0f; i < count; i++)
{
t += 2.0f * PI / count;
inner.t = 16.0f * t;
inner.color = multi(base, (0.35f + 0.6f * i / (count - 1.0f)));
DrawGear(&color, add(uv, multi(0.4f, make_float2(_cosf(t), _sinf(t)))), inner, eps);
}

DrawGear(&color, uv, outer, eps);
return color;
}