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Multithreading!
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@numberZero
numberZero committed Dec 7, 2023
1 parent 49077f6 commit 3367e67
Showing 1 changed file with 82 additions and 12 deletions.
94 changes: 82 additions & 12 deletions prog6.cxx
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Original file line number Diff line number Diff line change
Expand Up @@ -960,6 +960,10 @@ std::vector<VisualTraceResult> trace(std::vector<TrackPoint> rays) {
return result;
}

static const int thread_count = std::thread::hardware_concurrency();
static std::vector<GLFWwindow *> background_contexts;
static thread_local std::mt19937 gen{(unsigned long)glfwGetTimerValue()};

void render(GLFWwindow *wnd) {
{
struct {
Expand Down Expand Up @@ -993,8 +997,6 @@ void render(GLFWwindow *wnd) {
vec3 weight;
};

static thread_local std::mt19937 gen{(unsigned long)time(nullptr)};

static auto prepare_fullscreen_tracing = [] (const vec2 shape, const ivec2 ihalfsize) {
std::vector<TrackPoint> jobs;
jobs.reserve(4 * ihalfsize.x * ihalfsize.y);
Expand All @@ -1015,6 +1017,25 @@ void render(GLFWwindow *wnd) {
std::vector<ColorTraceJob> job_infos;
};

static auto prepare_fullscreen_tracing_mt = [] (const vec2 shape, const ivec2 ihalfsize, int thread_id) {
Batch out;
out.trace_jobs.reserve(4 * ihalfsize.x * ihalfsize.y / thread_count);
out.job_infos.reserve(4 * ihalfsize.x * ihalfsize.y / thread_count);
for (ivec2 ipos: irange(-ihalfsize + ivec2{0, thread_id}, ihalfsize, {1, thread_count})) {
const ivec2 zpos = ipos + ihalfsize;
const int pixel_index = 2 * ihalfsize.x * zpos.y + zpos.x;
vec2 wpos = (vec2(ipos) + .5f) / vec2(ihalfsize);
vec2 spos = shape * wpos;
TrackPoint pt;
pt.pos = me->loc.pos;
pt.dir = me->loc.rot * normalize(vec3(spos.x, 1.0f, spos.y));
pt.space = me->loc.space;
out.trace_jobs.push_back(pt);
out.job_infos.push_back({pixel_index, vec3(1.0f)});
}
return out;
};

static auto handle_thing_pixel = [] (Batch *batch, vec4 *colors, int const pixel_index, VisualTraceResult const& t, vec3 const weight, int const n_samples) {
static ball_distribution metal;
static sphere_distribution plastic;
Expand Down Expand Up @@ -1055,6 +1076,24 @@ void render(GLFWwindow *wnd) {
return out;
};

static auto trace_indexed_multipurpose = [] (vec4 *colors, vec4 *uvws, char *objects_mask, Batch in, const int n_samples) {
Batch out;
auto trace_result = trace(std::move(in.trace_jobs));
for (int k = 0; k < trace_result.size(); k++) {
const int pixel_index = in.job_infos[k].pixel_index;
auto const &t = trace_result[k];
if (t.thing) {
objects_mask[pixel_index] = 1;
handle_thing_pixel(&out, colors, pixel_index, t, vec3(1.0f), n_samples);
} else {
// colors[pixel_index] = vec4(sample(t.incident.dir), 1.0f); // maybe use this for hi-res rendering
colors[pixel_index] = {0, 0, 0, 0};
uvws[pixel_index] = vec4(t.incident.dir, 0.0f);
}
}
return out;
};

static auto trace_flat_multipurpose = [] (vec4 *colors, vec4 *uvws, char *objects_mask, std::vector<TrackPoint> in_jobs, const int n_samples) {
auto trace_result = trace(std::move(in_jobs));
Batch out;
Expand Down Expand Up @@ -1086,10 +1125,10 @@ void render(GLFWwindow *wnd) {
return objects_mask_2;
};

auto prepare_tracing_near_edges = [&] (const ivec2 ihalfsize, const char *objects_mask_2) {
auto prepare_tracing_near_edges = [&] (const ivec2 ihalfsize, const char *objects_mask_2, int thread_id) {
const ivec2 fine_size = 2 * settings::refine * ihalfsize;
Batch out;
for (ivec2 ipos: irange(-ihalfsize, ihalfsize)) {
for (ivec2 ipos: irange(-ihalfsize + ivec2{0, thread_id}, ihalfsize, {1, thread_count})) {
int coarse_index = (ipos.y + ihalfsize.y) * 2 * ihalfsize.x + (ipos.x + ihalfsize.x);
int mask = objects_mask_2[coarse_index];
if (mask == 0 || mask == 5)
Expand All @@ -1113,15 +1152,40 @@ void render(GLFWwindow *wnd) {
return out;
};

auto coarse_fullscreen_jobs = prepare_fullscreen_tracing(shape, ihalfsize);
auto coarse_thingy_jobs = trace_flat_multipurpose(colors.data(), uvws.data(), objects_mask.data(), std::move(coarse_fullscreen_jobs), 8);
for (int n_samples: {2, 2, 1, 1})
coarse_thingy_jobs = handle_interreflections_1(colors.data(), std::move(coarse_thingy_jobs), n_samples);
static auto parallel = [] (auto fn) {
std::thread ths[thread_count];
for (int th = 0; th < thread_count; th++) {
ths[th] = std::thread([&, th] () {
glfwMakeContextCurrent(background_contexts[th]);
fn(th);
glfwMakeContextCurrent(nullptr);
});
}
for (int th = 0; th < thread_count; th++)
ths[th].join();
};

auto objects_mask_2 = spread_mask(ihalfsize, objects_mask.data());
auto fine_thingy_jobs = prepare_tracing_near_edges(ihalfsize, objects_mask_2.data());
for (int n_samples: {4, 2, 1})
fine_thingy_jobs = handle_interreflections_1(fine_colors.data(), std::move(fine_thingy_jobs), n_samples);
if (settings::refine > 1) {
parallel([&] (int th) {
auto coarse_fullscreen_jobs = prepare_fullscreen_tracing_mt(shape, ihalfsize, th);
auto coarse_thingy_jobs = trace_indexed_multipurpose(colors.data(), uvws.data(), objects_mask.data(), std::move(coarse_fullscreen_jobs), 32);
for (int n_samples: {2, 2, 1, 1})
coarse_thingy_jobs = handle_interreflections_1(colors.data(), std::move(coarse_thingy_jobs), n_samples);
});

auto objects_mask_2 = spread_mask(ihalfsize, objects_mask.data());
parallel([&] (int th) {
auto fine_thingy_jobs = prepare_tracing_near_edges(ihalfsize, objects_mask_2.data(), th);
for (int n_samples: {4, 2, 1})
fine_thingy_jobs = handle_interreflections_1(fine_colors.data(), std::move(fine_thingy_jobs), n_samples);
});
} else {
parallel([&] (int th) {
auto jobs = prepare_fullscreen_tracing_mt(shape, ihalfsize, th);
for (int n_samples: {16, 2, 2, 1, 1})
jobs = handle_interreflections_1(colors.data(), std::move(jobs), n_samples);
});
}

double rtt2 = glfwGetTime();
rt_rays += uvws.size();
Expand Down Expand Up @@ -1404,6 +1468,9 @@ int main() try {
glfwWindowHint(GLFW_OPENGL_DEBUG_CONTEXT, GLFW_TRUE);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_COMPAT_PROFILE);
auto wnd = glfwCreateWindow(1600, 1200, title, nullptr, nullptr);
glfwWindowHint(GLFW_VISIBLE, GLFW_FALSE);
for (int k = 0; k < thread_count; k++)
background_contexts.push_back(glfwCreateWindow(1, 1, "OFFSCREEN", nullptr, wnd));
glfwMakeContextCurrent(wnd);
glDebugMessageCallback(debug, nullptr);
initGL();
Expand Down Expand Up @@ -1441,6 +1508,9 @@ int main() try {
frames = 0;
}
}
for (auto w: background_contexts)
glfwDestroyWindow(w);
background_contexts.clear();
glfwDestroyWindow(wnd);
#endif
} catch (char const *str) {
Expand Down

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