Blender, Cycles Render, call to function cause app to crash - c++

Question

I am trying to get the get the color of each sample during Cycles rendering. In order to do so, I am calling the following function
void update_bcd_inputs(int x, int y, float sampleR, float sampleG, float sampleB){
float current_valueR = sStats->m_meanImage.getValue(bcd::PixelPosition(x, y), 0); // += sampleR;
float current_valueG = sStats->m_meanImage.getValue(bcd::PixelPosition(x, y), 1); // += sampleG;
float current_valueB = sStats->m_meanImage.getValue(bcd::PixelPosition(x, y), 2); // += sampleB;
sStats->m_meanImage.set(x, y, 0, current_valueR + sampleR);
sStats->m_meanImage.set(x, y, 1, current_valueG + sampleG);
sStats->m_meanImage.set(x, y, 2, current_valueB + sampleB);
}
in blender/intern/cycles/device/device_cpu.cpp
void path_trace(DeviceTask &task, RenderTile &tile, KernelGlobals *kg)
{
float *render_buffer = (float*)tile.buffer;
int start_sample = tile.start_sample;
int end_sample = tile.start_sample + tile.num_samples;
float inv_weight = 1.0f/tile.num_samples;
for(int sample = start_sample; sample < end_sample; sample++) {
if(task.get_cancel() || task_pool.canceled()) {
if(task.need_finish_queue == false)
break;
}
for(int y = tile.y; y < tile.y + tile.h; y++) {
for(int x = tile.x; x < tile.x + tile.w; x++) {
path_trace_kernel()(kg, render_buffer,
sample, x, y, tile.offset, tile.stride);
int step = tile.offset + x + y*tile.stride;
step *= kernel_data.film.pass_stride;
float sampleR = *(render_buffer +step);
float sampleG = *(render_buffer +step +1);
float sampleB = *(render_buffer +step +2);
update_bcd_inputs(x, y, sampleR*inv_weight, sampleG*inv_weight, sampleB*inv_weight);
}
}
tile.sample = sample + 1;
task.update_progress(&tile, tile.w*tile.h);
}
}
SamplesStatisticsImages sStats is an attribute of CPUDevice
struct SamplesStatisticsImages
{
SamplesStatisticsImages() = default;
SamplesStatisticsImages(int i_width, int i_height, int i_nbOfBins);
SamplesStatisticsImages(const SamplesStatisticsImages&) = default;
SamplesStatisticsImages(SamplesStatisticsImages&&) = default;
SamplesStatisticsImages& operator=(const SamplesStatisticsImages&) = default;
SamplesStatisticsImages& operator=(SamplesStatisticsImages&&) = default;
DeepImage<float> m_nbOfSamplesImage;
DeepImage<float> m_meanImage;
DeepImage<float> m_covarImage;
DeepImage<float> m_histoImage;
};
Here are the files DeepImage.hpp and DeepImage.h.
The problem is that the call to update_bcd_inputs makes Blender to crash without even trying to render an image. I just change the renderer to Cycles, try to add a new material and boom, it crashes.
I figured out it is the set function that is the problem (when I remove it, the app doesn't crash).
Can someone understand why ? I don't have strong C++ skills so I must be missing something.
Here is the crash log as well.
Thanks !
Edit: more precisions
Here is the modified device_cpu.cpp.
The sStats pointer is initialized with nullptr in the CPUDevice constructor
CPUDevice(DeviceInfo& info_, Stats &stats_, bool background_)
: Device(info_, stats_, background_),
texture_info(this, "__texture_info", MEM_TEXTURE),
histoParams(),
#define REGISTER_KERNEL(name) name ## _kernel(KERNEL_FUNCTIONS(name))
...
#undef REGISTER_KERNEL
{
...
sStats = nullptr;
}
and then allocated in
void thread_render(DeviceTask& task)
{
...
sStats = new bcd::SamplesStatisticsImages(task.w, task.h, histoParams.m_nbOfBins);
...
}
histoParams is an attribute of CPUDevice as well.
struct HistogramParameters
{
HistogramParameters() :
m_nbOfBins(20),
m_gamma(2.2f),
m_maxValue(2.5f) {}
int m_nbOfBins;
float m_gamma; ///< exponent for the exponential size increase of histogram bins
float m_maxValue;
};