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#include "Halide.h"
namespace {
class ReactionDiffusionInit : public Halide::Generator<ReactionDiffusionInit> {
public:
Output<Buffer<float, 3>> output{"output"};
GeneratorParam<bool> threads{"threads", true};
void generate() {
output(x, y, c) = Halide::random_float();
}
void schedule() {
output.vectorize(x, natural_vector_size<float>());
if (threads) {
output.parallel(y, 8);
}
}
private:
Var x, y, xi, yi, c;
};
class ReactionDiffusionUpdate : public Halide::Generator<ReactionDiffusionUpdate> {
public:
Input<Buffer<float, 3>> state{"state"};
Input<int> mouse_x{"mouse_x"};
Input<int> mouse_y{"mouse_y"};
Input<int> frame{"frame"};
Output<Buffer<float, 3>> new_state{"new_state"};
GeneratorParam<bool> threads{"threads", false};
void generate() {
clamped = Halide::BoundaryConditions::repeat_edge(state);
blur_x(x, y, c) = (clamped(x - 2, y, c) +
clamped(x - 1, y, c) +
clamped(x, y, c) +
clamped(x + 1, y, c) +
clamped(x + 2, y, c));
blur_y(x, y, c) = (clamped(x, y - 2, c) +
clamped(x, y - 1, c) +
clamped(x, y, c) +
clamped(x, y + 1, c) +
clamped(x, y + 2, c));
blur(x, y, c) = (blur_x(x, y, c) + blur_y(x, y, c)) / 10;
Expr R = blur(x, y, 0);
Expr G = blur(x, y, 1);
Expr B = blur(x, y, 2);
// Push the colors outwards with a sigmoid
Expr s = 0.5f;
R *= (1 - s) + s * R * (3 - 2 * R);
G *= (1 - s) + s * G * (3 - 2 * G);
B *= (1 - s) + s * B * (3 - 2 * B);
// Reaction
Expr dR = B * (1 - R - G);
Expr dG = (1 - B) * (R - G);
Expr dB = 1 - B + 2 * G * R - R - G;
// Boost reaction rate using distance from mouse
Expr mx = (mouse_x - x);
Expr my = (mouse_y - y);
Expr boost = 5 * max(0, (1.f - (mx * mx + my * my) * 0.001f)) + 1;
R += dR * 0.14f * boost;
G += dG * 0.05f * boost;
B += dB * 0.065f * boost;
R = clamp(R, 0.0f, 1.0f);
G = clamp(G, 0.0f, 1.0f);
B = clamp(B, 0.0f, 1.0f);
new_state(x, y, c) = mux(c, {R, G, B});
// Noise at the edges
new_state(x, state.dim(1).min(), c) = random_float(frame) * 0.2f;
new_state(x, state.dim(1).max(), c) = random_float(frame) * 0.2f;
new_state(state.dim(0).min(), y, c) = random_float(frame) * 0.2f;
new_state(state.dim(0).max(), y, c) = random_float(frame) * 0.2f;
noise(x, y, c) = random_float(frame);
blurry_noise(x, y, c) = 0.25f * (noise(x, y, c) +
noise(x + 1, y, c) +
noise(x + 1, y + 1, c) +
noise(x, y + 1, c));
// Add some noise where the mouse is
Expr min_x = clamp(mouse_x - 10, 0, state.dim(0).extent() - 1);
Expr max_x = clamp(mouse_x + 10, 0, state.dim(0).extent() - 1);
Expr min_y = clamp(mouse_y - 10, 0, state.dim(1).extent() - 1);
Expr max_y = clamp(mouse_y + 10, 0, state.dim(1).extent() - 1);
clobber = RDom(min_x, max_x - min_x + 1, min_y, max_y - min_y + 1);
Expr dx = clobber.x - mouse_x;
Expr dy = clobber.y - mouse_y;
Expr radius = dx * dx + dy * dy;
new_state(clobber.x, clobber.y, c) = select(radius < 100.0f,
blurry_noise(clobber.x, clobber.y, c),
new_state(clobber.x, clobber.y, c));
}
void schedule() {
state.dim(2).set_bounds(0, 3);
new_state
.reorder(c, x, y)
.bound(c, 0, 3)
.unroll(c);
noise.compute_root()
.vectorize(x, natural_vector_size<float>());
new_state
.tile(x, y, xi, yi, 256, 8)
.vectorize(xi, natural_vector_size<float>());
for (int i = 0; i < 5; i++) {
new_state.update(i).unscheduled();
}
blur
.compute_at(new_state, xi)
.vectorize(x);
clamped
.store_at(new_state, x)
.compute_at(new_state, yi);
if (threads) {
new_state.parallel(y);
}
}
private:
Func blur_x, blur_y, blur, clamped, noise, blurry_noise;
Var x, y, xi, yi, c;
RDom clobber;
};
class ReactionDiffusionRender : public Halide::Generator<ReactionDiffusionRender> {
public:
Input<Buffer<float, 3>> state{"state"};
Output<Buffer<uint32_t, 2>> render{"render"};
GeneratorParam<bool> threads{"threads", false};
void generate() {
Func contour;
Expr v = state(x, y, c) * (1.01f - state(x, y, c)) * 4;
v *= v;
v *= v;
v = min(v, 1.0f);
contour(x, y, c) = v;
Expr c0 = contour(x, y, 0);
Expr c1 = contour(x, y, 1);
Expr c2 = contour(x, y, 2);
Expr R = min(c0, (c1 + c2) / 2);
Expr G = clamp((c1 + c0 + c2) / 2, 0.0f, 1.0f);
Expr B = max(c0, max(c1, c2));
R = cast<uint32_t>(R * 255) & 0xff;
G = cast<uint32_t>(G * 255) & 0xff;
B = cast<uint32_t>(B * 255) & 0xff;
Expr A = cast<uint32_t>(255);
Expr bgra = B | (G << 8) | (R << 16) | (A << 24);
render(x, y) = bgra;
}
void schedule() {
render
.vectorize(x, natural_vector_size<float>());
if (threads) {
render.parallel(y, 4);
}
}
private:
Var x, y, c, xi, yi;
};
} // namespace
HALIDE_REGISTER_GENERATOR(ReactionDiffusionInit, reaction_diffusion_init)
HALIDE_REGISTER_GENERATOR(ReactionDiffusionUpdate, reaction_diffusion_update)
HALIDE_REGISTER_GENERATOR(ReactionDiffusionRender, reaction_diffusion_render)
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