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pcdet/ops/pointnet2/pointnet2_batch/src/group_points_gpu.cu

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+/*
+batch version of point grouping, modified from the original implementation of official PointNet++ codes.
+Written by Shaoshuai Shi
+All Rights Reserved 2018.
+*/
+
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "cuda_utils.h"
+#include "group_points_gpu.h"
+
+
+__global__ void group_points_grad_kernel_fast(int b, int c, int n, int npoints, int nsample, 
+    const float *__restrict__ grad_out, const int *__restrict__ idx, float *__restrict__ grad_points) {
+    // grad_out: (B, C, npoints, nsample)
+    // idx: (B, npoints, nsample)
+    // output:
+    //      grad_points: (B, C, N)
+    int bs_idx = blockIdx.z;
+    int c_idx = blockIdx.y;
+    int index = blockIdx.x * blockDim.x + threadIdx.x;
+    int pt_idx = index / nsample;
+    if (bs_idx >= b || c_idx >= c || pt_idx >= npoints) return;
+
+    int sample_idx = index % nsample;
+    grad_out += bs_idx * c * npoints * nsample + c_idx * npoints * nsample + pt_idx * nsample + sample_idx;
+    idx += bs_idx * npoints * nsample + pt_idx * nsample + sample_idx; 
+    
+    atomicAdd(grad_points + bs_idx * c * n + c_idx * n + idx[0] , grad_out[0]);
+}
+
+void group_points_grad_kernel_launcher_fast(int b, int c, int n, int npoints, int nsample, 
+    const float *grad_out, const int *idx, float *grad_points) {
+    // grad_out: (B, C, npoints, nsample)
+    // idx: (B, npoints, nsample)
+    // output:
+    //      grad_points: (B, C, N)
+    cudaError_t err;
+    dim3 blocks(DIVUP(npoints * nsample, THREADS_PER_BLOCK), c, b);  // blockIdx.x(col), blockIdx.y(row)
+    dim3 threads(THREADS_PER_BLOCK);
+
+    group_points_grad_kernel_fast<<<blocks, threads>>>(b, c, n, npoints, nsample, grad_out, idx, grad_points);
+
+    err = cudaGetLastError();
+    if (cudaSuccess != err) {
+        fprintf(stderr, "CUDA kernel failed : %s\n", cudaGetErrorString(err));
+        exit(-1);
+    }
+}
+
+
+__global__ void group_points_kernel_fast(int b, int c, int n, int npoints, int nsample, 
+    const float *__restrict__ points, const int *__restrict__ idx, float *__restrict__ out) {
+    // points: (B, C, N)
+    // idx: (B, npoints, nsample)
+    // output:
+    //      out: (B, C, npoints, nsample)
+    int bs_idx = blockIdx.z;
+    int c_idx = blockIdx.y;
+    int index = blockIdx.x * blockDim.x + threadIdx.x;
+    int pt_idx = index / nsample;
+    if (bs_idx >= b || c_idx >= c || pt_idx >= npoints) return;
+
+    int sample_idx = index % nsample;
+
+    idx += bs_idx * npoints * nsample + pt_idx * nsample + sample_idx; 
+    int in_idx = bs_idx * c * n + c_idx * n + idx[0];
+    int out_idx = bs_idx * c * npoints * nsample + c_idx * npoints * nsample + pt_idx * nsample + sample_idx;
+
+    out[out_idx] = points[in_idx];
+}
+
+
+void group_points_kernel_launcher_fast(int b, int c, int n, int npoints, int nsample, 
+    const float *points, const int *idx, float *out) {
+    // points: (B, C, N)
+    // idx: (B, npoints, nsample)
+    // output:
+    //      out: (B, C, npoints, nsample)
+    cudaError_t err;
+    dim3 blocks(DIVUP(npoints * nsample, THREADS_PER_BLOCK), c, b);  // blockIdx.x(col), blockIdx.y(row)
+    dim3 threads(THREADS_PER_BLOCK);
+
+    group_points_kernel_fast<<<blocks, threads>>>(b, c, n, npoints, nsample, points, idx, out);
+    // cudaDeviceSynchronize();  // for using printf in kernel function
+    err = cudaGetLastError();
+    if (cudaSuccess != err) {
+        fprintf(stderr, "CUDA kernel failed : %s\n", cudaGetErrorString(err));
+        exit(-1);
+    }
+}