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++ // Copyright 2009-2021 Intel Corporation
++ // SPDX-License-Identifier: Apache-2.0
++
++ #pragma once
++
++ namespace embree
++ {
++ /* adjust discret tessellation level for feature-adaptive pre-subdivision */
++ __forceinline float adjustTessellationLevel(float l, const size_t sublevel)
++ {
++ for (size_t i=0; i<sublevel; i++) l *= 0.5f;
++ float r = ceilf(l);
++ for (size_t i=0; i<sublevel; i++) r *= 2.0f;
++ return r;
++ }
++
++ __forceinline int stitch(const int x, const int fine, const int coarse) {
++ return (2*x+1)*coarse/(2*fine);
++ }
++
++ __forceinline void stitchGridEdges(const unsigned int low_rate,
++ const unsigned int high_rate,
++ const unsigned int x0,
++ const unsigned int x1,
++ float * __restrict__ const uv_array,
++ const unsigned int uv_array_step)
++ {
++ #if 1
++ const float inv_low_rate = rcp((float)(low_rate-1));
++ for (unsigned x=x0; x<=x1; x++) {
++ uv_array[(x-x0)*uv_array_step] = float(stitch(x,high_rate-1,low_rate-1))*inv_low_rate;
++ }
++ if (unlikely(x1 == high_rate-1))
++ uv_array[(x1-x0)*uv_array_step] = 1.0f;
++ #else
++ assert(low_rate < high_rate);
++ assert(high_rate >= 2);
++
++ const float inv_low_rate = rcp((float)(low_rate-1));
++ const unsigned int dy = low_rate - 1;
++ const unsigned int dx = high_rate - 1;
++
++ int p = 2*dy-dx;
++
++ unsigned int offset = 0;
++ unsigned int y = 0;
++ float value = 0.0f;
++ for(unsigned int x=0;x<high_rate-1; x++) // '<=' would be correct but we will leave the 1.0f at the end
++ {
++ uv_array[offset] = value;
++
++ offset += uv_array_step;
++ if (unlikely(p > 0))
++ {
++ y++;
++ value = (float)y * inv_low_rate;
++ p -= 2*dx;
++ }
++ p += 2*dy;
++ }
++ #endif
++ }
++
++ __forceinline void stitchUVGrid(const float edge_levels[4],
++ const unsigned int swidth,
++ const unsigned int sheight,
++ const unsigned int x0,
++ const unsigned int y0,
++ const unsigned int grid_u_res,
++ const unsigned int grid_v_res,
++ float * __restrict__ const u_array,
++ float * __restrict__ const v_array)
++ {
++ const unsigned int x1 = x0+grid_u_res-1;
++ const unsigned int y1 = y0+grid_v_res-1;
++ const unsigned int int_edge_points0 = (unsigned int)edge_levels[0] + 1;
++ const unsigned int int_edge_points1 = (unsigned int)edge_levels[1] + 1;
++ const unsigned int int_edge_points2 = (unsigned int)edge_levels[2] + 1;
++ const unsigned int int_edge_points3 = (unsigned int)edge_levels[3] + 1;
++
++ if (unlikely(y0 == 0 && int_edge_points0 < swidth))
++ stitchGridEdges(int_edge_points0,swidth,x0,x1,u_array,1);
++
++ if (unlikely(y1 == sheight-1 && int_edge_points2 < swidth))
++ stitchGridEdges(int_edge_points2,swidth,x0,x1,&u_array[(grid_v_res-1)*grid_u_res],1);
++
++ if (unlikely(x0 == 0 && int_edge_points1 < sheight))
++ stitchGridEdges(int_edge_points1,sheight,y0,y1,&v_array[grid_u_res-1],grid_u_res);
++
++ if (unlikely(x1 == swidth-1 && int_edge_points3 < sheight))
++ stitchGridEdges(int_edge_points3,sheight,y0,y1,v_array,grid_u_res);
++ }
++
++ __forceinline void gridUVTessellator(const float edge_levels[4],
++ const unsigned int swidth,
++ const unsigned int sheight,
++ const unsigned int x0,
++ const unsigned int y0,
++ const unsigned int grid_u_res,
++ const unsigned int grid_v_res,
++ float * __restrict__ const u_array,
++ float * __restrict__ const v_array)
++ {
++ assert( grid_u_res >= 1);
++ assert( grid_v_res >= 1);
++ assert( edge_levels[0] >= 1.0f );
++ assert( edge_levels[1] >= 1.0f );
++ assert( edge_levels[2] >= 1.0f );
++ assert( edge_levels[3] >= 1.0f );
++
++ #if defined(__AVX__)
++ const vint8 grid_u_segments = vint8(swidth)-1;
++ const vint8 grid_v_segments = vint8(sheight)-1;
++
++ const vfloat8 inv_grid_u_segments = rcp(vfloat8(grid_u_segments));
++ const vfloat8 inv_grid_v_segments = rcp(vfloat8(grid_v_segments));
++
++ unsigned int index = 0;
++ vint8 v_i( zero );
++ for (unsigned int y=0;y<grid_v_res;y++,index+=grid_u_res,v_i += 1)
++ {
++ vint8 u_i ( step );
++
++ const vbool8 m_v = v_i < grid_v_segments;
++
++ for (unsigned int x=0;x<grid_u_res;x+=8, u_i += 8)
++ {
++ const vbool8 m_u = u_i < grid_u_segments;
++ const vfloat8 u = select(m_u, vfloat8(x0+u_i) * inv_grid_u_segments, 1.0f);
++ const vfloat8 v = select(m_v, vfloat8(y0+v_i) * inv_grid_v_segments, 1.0f);
++ vfloat8::storeu(&u_array[index + x],u);
++ vfloat8::storeu(&v_array[index + x],v);
++ }
++ }
++ #else
++ const vint4 grid_u_segments = vint4(swidth)-1;
++ const vint4 grid_v_segments = vint4(sheight)-1;
++
++ const vfloat4 inv_grid_u_segments = rcp(vfloat4(grid_u_segments));
++ const vfloat4 inv_grid_v_segments = rcp(vfloat4(grid_v_segments));
++
++ unsigned int index = 0;
++ vint4 v_i( zero );
++ for (unsigned int y=0;y<grid_v_res;y++,index+=grid_u_res,v_i += 1)
++ {
++ vint4 u_i ( step );
++
++ const vbool4 m_v = v_i < grid_v_segments;
++
++ for (unsigned int x=0;x<grid_u_res;x+=4, u_i += 4)
++ {
++ const vbool4 m_u = u_i < grid_u_segments;
++ const vfloat4 u = select(m_u, vfloat4(x0+u_i) * inv_grid_u_segments, 1.0f);
++ const vfloat4 v = select(m_v, vfloat4(y0+v_i) * inv_grid_v_segments, 1.0f);
++ vfloat4::storeu(&u_array[index + x],u);
++ vfloat4::storeu(&v_array[index + x],v);
++ }
++ }
++ #endif
++ }
++ }