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/* Copyright (c) 2022, NVIDIA CORPORATION. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* * Neither the name of NVIDIA CORPORATION nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "common.h"
///////////////////////////////////////////////////////////////////////////////
/// \brief warp image with a given displacement field, CUDA kernel.
/// \param[in] width image width
/// \param[in] height image height
/// \param[in] stride image stride
/// \param[in] u horizontal displacement
/// \param[in] v vertical displacement
/// \param[out] out result
///////////////////////////////////////////////////////////////////////////////
__global__ void WarpingKernel(int width, int height, int stride, const float *u,
const float *v, float *out,
cudaTextureObject_t texToWarp) {
const int ix = threadIdx.x + blockIdx.x * blockDim.x;
const int iy = threadIdx.y + blockIdx.y * blockDim.y;
const int pos = ix + iy * stride;
if (ix >= width || iy >= height) return;
float x = ((float)ix + u[pos] + 0.5f) / (float)width;
float y = ((float)iy + v[pos] + 0.5f) / (float)height;
out[pos] = tex2D<float>(texToWarp, x, y);
}
///////////////////////////////////////////////////////////////////////////////
/// \brief warp image with provided vector field, CUDA kernel wrapper.
///
/// For each output pixel there is a vector which tells which pixel
/// from a source image should be mapped to this particular output
/// pixel.
/// It is assumed that images and the vector field have the same stride and
/// resolution.
/// \param[in] src source image
/// \param[in] w width
/// \param[in] h height
/// \param[in] s stride
/// \param[in] u horizontal displacement
/// \param[in] v vertical displacement
/// \param[out] out warped image
///////////////////////////////////////////////////////////////////////////////
static void WarpImage(const float *src, int w, int h, int s, const float *u,
const float *v, float *out) {
dim3 threads(32, 6);
dim3 blocks(iDivUp(w, threads.x), iDivUp(h, threads.y));
cudaTextureObject_t texToWarp;
cudaResourceDesc texRes;
memset(&texRes, 0, sizeof(cudaResourceDesc));
texRes.resType = cudaResourceTypePitch2D;
texRes.res.pitch2D.devPtr = (void *)src;
texRes.res.pitch2D.desc = cudaCreateChannelDesc<float>();
texRes.res.pitch2D.width = w;
texRes.res.pitch2D.height = h;
texRes.res.pitch2D.pitchInBytes = s * sizeof(float);
cudaTextureDesc texDescr;
memset(&texDescr, 0, sizeof(cudaTextureDesc));
texDescr.normalizedCoords = true;
texDescr.filterMode = cudaFilterModeLinear;
texDescr.addressMode[0] = cudaAddressModeMirror;
texDescr.addressMode[1] = cudaAddressModeMirror;
texDescr.readMode = cudaReadModeElementType;
checkCudaErrors(
cudaCreateTextureObject(&texToWarp, &texRes, &texDescr, NULL));
WarpingKernel<<<blocks, threads>>>(w, h, s, u, v, out, texToWarp);
}
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