Files
test/intern/cycles/kernel/kernels/cuda/kernel.cu
Stefan Werner 51e898324d Adaptive Sampling for Cycles.
This feature takes some inspiration from
"RenderMan: An Advanced Path Tracing Architecture for Movie Rendering" and
"A Hierarchical Automatic Stopping Condition for Monte Carlo Global Illumination"

The basic principle is as follows:
While samples are being added to a pixel, the adaptive sampler writes half
of the samples to a separate buffer. This gives it two separate estimates
of the same pixel, and by comparing their difference it estimates convergence.
Once convergence drops below a given threshold, the pixel is considered done.

When a pixel has not converged yet and needs more samples than the minimum,
its immediate neighbors are also set to take more samples. This is done in order
to more reliably detect sharp features such as caustics. A 3x3 box filter that
is run periodically over the tile buffer is used for that purpose.

After a tile has finished rendering, the values of all passes are scaled as if
they were rendered with the full number of samples. This way, any code operating
on these buffers, for example the denoiser, does not need to be changed for
per-pixel sample counts.

Reviewed By: brecht, #cycles

Differential Revision: https://developer.blender.org/D4686
2020-03-05 12:21:38 +01:00

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/*
* Copyright 2011-2013 Blender Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/* CUDA kernel entry points */
#ifdef __CUDA_ARCH__
#include "kernel/kernel_compat_cuda.h"
#include "kernel_config.h"
#include "util/util_atomic.h"
#include "kernel/kernel_math.h"
#include "kernel/kernel_types.h"
#include "kernel/kernel_globals.h"
#include "kernel/kernel_color.h"
#include "kernel/kernels/cuda/kernel_cuda_image.h"
#include "kernel/kernel_film.h"
#include "kernel/kernel_path.h"
#include "kernel/kernel_path_branched.h"
#include "kernel/kernel_bake.h"
#include "kernel/kernel_work_stealing.h"
#include "kernel/kernel_adaptive_sampling.h"
/* kernels */
extern "C" __global__ void
CUDA_LAUNCH_BOUNDS(CUDA_THREADS_BLOCK_WIDTH, CUDA_KERNEL_MAX_REGISTERS)
kernel_cuda_path_trace(WorkTile *tile, uint total_work_size)
{
int work_index = ccl_global_id(0);
bool thread_is_active = work_index < total_work_size;
uint x, y, sample;
KernelGlobals kg;
if(thread_is_active) {
get_work_pixel(tile, work_index, &x, &y, &sample);
kernel_path_trace(&kg, tile->buffer, sample, x, y, tile->offset, tile->stride);
}
if(kernel_data.film.cryptomatte_passes) {
__syncthreads();
if(thread_is_active) {
kernel_cryptomatte_post(&kg, tile->buffer, sample, x, y, tile->offset, tile->stride);
}
}
}
#ifdef __BRANCHED_PATH__
extern "C" __global__ void
CUDA_LAUNCH_BOUNDS(CUDA_THREADS_BLOCK_WIDTH, CUDA_KERNEL_BRANCHED_MAX_REGISTERS)
kernel_cuda_branched_path_trace(WorkTile *tile, uint total_work_size)
{
int work_index = ccl_global_id(0);
bool thread_is_active = work_index < total_work_size;
uint x, y, sample;
KernelGlobals kg;
if(thread_is_active) {
get_work_pixel(tile, work_index, &x, &y, &sample);
kernel_branched_path_trace(&kg, tile->buffer, sample, x, y, tile->offset, tile->stride);
}
if(kernel_data.film.cryptomatte_passes) {
__syncthreads();
if(thread_is_active) {
kernel_cryptomatte_post(&kg, tile->buffer, sample, x, y, tile->offset, tile->stride);
}
}
}
#endif
extern "C" __global__ void
CUDA_LAUNCH_BOUNDS(CUDA_THREADS_BLOCK_WIDTH, CUDA_KERNEL_MAX_REGISTERS)
kernel_cuda_adaptive_stopping(WorkTile *tile, int sample, uint total_work_size)
{
int work_index = ccl_global_id(0);
bool thread_is_active = work_index < total_work_size;
KernelGlobals kg;
if(thread_is_active && kernel_data.film.pass_adaptive_aux_buffer) {
uint x = tile->x + work_index % tile->w;
uint y = tile->y + work_index / tile->w;
int index = tile->offset + x + y * tile->stride;
ccl_global float *buffer = tile->buffer + index * kernel_data.film.pass_stride;
kernel_do_adaptive_stopping(&kg, buffer, sample);
}
}
extern "C" __global__ void
CUDA_LAUNCH_BOUNDS(CUDA_THREADS_BLOCK_WIDTH, CUDA_KERNEL_MAX_REGISTERS)
kernel_cuda_adaptive_filter_x(WorkTile *tile, int sample, uint)
{
KernelGlobals kg;
if(kernel_data.film.pass_adaptive_aux_buffer && sample > kernel_data.integrator.adaptive_min_samples) {
if(ccl_global_id(0) < tile->h) {
int y = tile->y + ccl_global_id(0);
kernel_do_adaptive_filter_x(&kg, y, tile);
}
}
}
extern "C" __global__ void
CUDA_LAUNCH_BOUNDS(CUDA_THREADS_BLOCK_WIDTH, CUDA_KERNEL_MAX_REGISTERS)
kernel_cuda_adaptive_filter_y(WorkTile *tile, int sample, uint)
{
KernelGlobals kg;
if(kernel_data.film.pass_adaptive_aux_buffer && sample > kernel_data.integrator.adaptive_min_samples) {
if(ccl_global_id(0) < tile->w) {
int x = tile->x + ccl_global_id(0);
kernel_do_adaptive_filter_y(&kg, x, tile);
}
}
}
extern "C" __global__ void
CUDA_LAUNCH_BOUNDS(CUDA_THREADS_BLOCK_WIDTH, CUDA_KERNEL_MAX_REGISTERS)
kernel_cuda_adaptive_scale_samples(WorkTile *tile, int start_sample, int sample, uint total_work_size)
{
if(kernel_data.film.pass_adaptive_aux_buffer) {
int work_index = ccl_global_id(0);
bool thread_is_active = work_index < total_work_size;
KernelGlobals kg;
if(thread_is_active) {
uint x = tile->x + work_index % tile->w;
uint y = tile->y + work_index / tile->w;
int index = tile->offset + x + y * tile->stride;
ccl_global float *buffer = tile->buffer + index * kernel_data.film.pass_stride;
if(buffer[kernel_data.film.pass_sample_count] < 0.0f) {
buffer[kernel_data.film.pass_sample_count] = -buffer[kernel_data.film.pass_sample_count];
float sample_multiplier = sample / max((float)start_sample + 1.0f, buffer[kernel_data.film.pass_sample_count]);
if(sample_multiplier != 1.0f) {
kernel_adaptive_post_adjust(&kg, buffer, sample_multiplier);
}
}
else {
kernel_adaptive_post_adjust(&kg, buffer, sample / (sample - 1.0f));
}
}
}
}
extern "C" __global__ void
CUDA_LAUNCH_BOUNDS(CUDA_THREADS_BLOCK_WIDTH, CUDA_KERNEL_MAX_REGISTERS)
kernel_cuda_convert_to_byte(uchar4 *rgba, float *buffer, float sample_scale, int sx, int sy, int sw, int sh, int offset, int stride)
{
int x = sx + blockDim.x*blockIdx.x + threadIdx.x;
int y = sy + blockDim.y*blockIdx.y + threadIdx.y;
if(x < sx + sw && y < sy + sh) {
kernel_film_convert_to_byte(NULL, rgba, buffer, sample_scale, x, y, offset, stride);
}
}
extern "C" __global__ void
CUDA_LAUNCH_BOUNDS(CUDA_THREADS_BLOCK_WIDTH, CUDA_KERNEL_MAX_REGISTERS)
kernel_cuda_convert_to_half_float(uchar4 *rgba, float *buffer, float sample_scale, int sx, int sy, int sw, int sh, int offset, int stride)
{
int x = sx + blockDim.x*blockIdx.x + threadIdx.x;
int y = sy + blockDim.y*blockIdx.y + threadIdx.y;
if(x < sx + sw && y < sy + sh) {
kernel_film_convert_to_half_float(NULL, rgba, buffer, sample_scale, x, y, offset, stride);
}
}
extern "C" __global__ void
CUDA_LAUNCH_BOUNDS(CUDA_THREADS_BLOCK_WIDTH, CUDA_KERNEL_MAX_REGISTERS)
kernel_cuda_displace(uint4 *input,
float4 *output,
int type,
int sx,
int sw,
int offset,
int sample)
{
int x = sx + blockDim.x*blockIdx.x + threadIdx.x;
if(x < sx + sw) {
KernelGlobals kg;
kernel_displace_evaluate(&kg, input, output, x);
}
}
extern "C" __global__ void
CUDA_LAUNCH_BOUNDS(CUDA_THREADS_BLOCK_WIDTH, CUDA_KERNEL_MAX_REGISTERS)
kernel_cuda_background(uint4 *input,
float4 *output,
int type,
int sx,
int sw,
int offset,
int sample)
{
int x = sx + blockDim.x*blockIdx.x + threadIdx.x;
if(x < sx + sw) {
KernelGlobals kg;
kernel_background_evaluate(&kg, input, output, x);
}
}
#ifdef __BAKING__
extern "C" __global__ void
CUDA_LAUNCH_BOUNDS(CUDA_THREADS_BLOCK_WIDTH, CUDA_KERNEL_MAX_REGISTERS)
kernel_cuda_bake(uint4 *input, float4 *output, int type, int filter, int sx, int sw, int offset, int sample)
{
int x = sx + blockDim.x*blockIdx.x + threadIdx.x;
if(x < sx + sw) {
KernelGlobals kg;
kernel_bake_evaluate(&kg, input, output, (ShaderEvalType)type, filter, x, offset, sample);
}
}
#endif
#endif