318 lines
9.9 KiB
C++
318 lines
9.9 KiB
C++
// -*- mode: c++ -*-
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/*
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Copyright (c) 2010-2011, Intel Corporation
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions are
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met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in the
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documentation and/or other materials provided with the distribution.
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* Neither the name of Intel Corporation nor the names of its
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contributors may be used to endorse or promote products derived from
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this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
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IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A
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PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
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OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
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LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
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NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
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SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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Based on Syoyo Fujita's aobench: http://code.google.com/p/aobench
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*/
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#define NAO_SAMPLES 8
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#define M_PI 3.1415926535f
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typedef float<3> vec;
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struct Isect {
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float t;
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vec p;
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vec n;
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int hit;
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};
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struct Sphere {
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vec center;
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float radius;
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};
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struct Plane {
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vec p;
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vec n;
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};
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struct Ray {
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vec org;
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vec dir;
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};
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static inline float dot(vec a, vec b) {
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return a.x * b.x + a.y * b.y + a.z * b.z;
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}
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static inline vec vcross(vec v0, vec v1) {
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vec ret;
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ret.x = v0.y * v1.z - v0.z * v1.y;
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ret.y = v0.z * v1.x - v0.x * v1.z;
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ret.z = v0.x * v1.y - v0.y * v1.x;
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return ret;
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}
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static inline void vnormalize(reference vec v) {
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float len2 = dot(v, v);
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float invlen = rsqrt(len2);
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v *= invlen;
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}
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static inline void
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ray_plane_intersect(reference Isect isect, reference Ray ray,
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reference Plane plane) {
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float d = -dot(plane.p, plane.n);
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float v = dot(ray.dir, plane.n);
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cif (abs(v) < 1.0e-17)
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return;
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else {
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float t = -(dot(ray.org, plane.n) + d) / v;
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cif ((t > 0.0) && (t < isect.t)) {
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isect.t = t;
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isect.hit = 1;
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isect.p = ray.org + ray.dir * t;
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isect.n = plane.n;
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}
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}
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}
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static inline void
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ray_sphere_intersect(reference Isect isect, reference Ray ray,
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reference Sphere sphere) {
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vec rs = ray.org - sphere.center;
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float B = dot(rs, ray.dir);
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float C = dot(rs, rs) - sphere.radius * sphere.radius;
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float D = B * B - C;
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cif (D > 0.) {
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float t = -B - sqrt(D);
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cif ((t > 0.0) && (t < isect.t)) {
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isect.t = t;
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isect.hit = 1;
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isect.p = ray.org + t * ray.dir;
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isect.n = isect.p - sphere.center;
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vnormalize(isect.n);
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}
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}
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}
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static inline void
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orthoBasis(reference vec basis[3], vec n) {
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basis[2] = n;
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basis[1].x = 0.0; basis[1].y = 0.0; basis[1].z = 0.0;
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if ((n.x < 0.6) && (n.x > -0.6)) {
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basis[1].x = 1.0;
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} else if ((n.y < 0.6) && (n.y > -0.6)) {
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basis[1].y = 1.0;
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} else if ((n.z < 0.6) && (n.z > -0.6)) {
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basis[1].z = 1.0;
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} else {
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basis[1].x = 1.0;
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}
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basis[0] = vcross(basis[1], basis[2]);
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vnormalize(basis[0]);
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basis[1] = vcross(basis[2], basis[0]);
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vnormalize(basis[1]);
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}
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static inline float
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ambient_occlusion(reference Isect isect, reference Plane plane,
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reference Sphere spheres[3], reference RNGState rngstate) {
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float eps = 0.0001f;
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vec p, n;
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vec basis[3];
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float occlusion = 0.0;
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p = isect.p + eps * isect.n;
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orthoBasis(basis, isect.n);
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static const uniform int ntheta = NAO_SAMPLES;
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static const uniform int nphi = NAO_SAMPLES;
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for (uniform int j = 0; j < ntheta; j++) {
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for (uniform int i = 0; i < nphi; i++) {
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Ray ray;
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Isect occIsect;
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float theta = sqrt(frandom(rngstate));
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float phi = 2.0f * M_PI * frandom(rngstate);
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float x = cos(phi) * theta;
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float y = sin(phi) * theta;
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float z = sqrt(1.0 - theta * theta);
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// local . global
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float rx = x * basis[0].x + y * basis[1].x + z * basis[2].x;
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float ry = x * basis[0].y + y * basis[1].y + z * basis[2].y;
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float rz = x * basis[0].z + y * basis[1].z + z * basis[2].z;
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ray.org = p;
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ray.dir.x = rx;
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ray.dir.y = ry;
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ray.dir.z = rz;
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occIsect.t = 1.0e+17;
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occIsect.hit = 0;
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for (uniform int snum = 0; snum < 3; ++snum)
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ray_sphere_intersect(occIsect, ray, spheres[snum]);
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ray_plane_intersect (occIsect, ray, plane);
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if (occIsect.hit) occlusion += 1.0;
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}
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}
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occlusion = (ntheta * nphi - occlusion) / (float)(ntheta * nphi);
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return occlusion;
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}
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/* Compute the image for the scanlines from [y0,y1), for an overall image
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of width w and height h.
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*/
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void ao_scanlines(uniform int y0, uniform int y1, uniform int w, uniform int h,
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uniform int nsubsamples, reference uniform float image[]) {
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static Plane plane = { { 0.0f, -0.5f, 0.0f }, { 0.f, 1.f, 0.f } };
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static Sphere spheres[3] = {
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{ { -2.0f, 0.0f, -3.5f }, 0.5f },
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{ { -0.5f, 0.0f, -3.0f }, 0.5f },
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{ { 1.0f, 0.0f, -2.2f }, 0.5f } };
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RNGState rngstate;
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seed_rng(rngstate, y0);
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// Compute the mapping between the 'programCount'-wide program
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// instances running in parallel and samples in the image.
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//
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// For now, we'll always take four samples per pixel, so start by
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// initializing du and dv with offsets into subpixel samples. We'll
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// take care of further updating du and dv for the case where we're
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// doing more than 4 program instances in parallel shortly.
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uniform float uSteps[4] = { 0, 1, 0, 1 };
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uniform float vSteps[4] = { 0, 0, 1, 1 };
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float du = uSteps[programIndex % 4] / nsubsamples;
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float dv = vSteps[programIndex % 4] / nsubsamples;
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// Now handle the case where we are able to do more than one pixel's
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// worth of work at once. nx records the number of pixels in the x
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// direction we do per iteration and ny the number in y.
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uniform int nx = 1, ny = 1;
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if (programCount == 8) {
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// Do two pixels at once in the x direction
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nx = 2;
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if (programIndex >= 4)
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// And shift the offsets for the second pixel's worth of work
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++du;
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}
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else if (programCount == 16) {
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// Two at once in both x and y
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nx = ny = 2;
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if ((programIndex >= 4 && programIndex < 8) || programIndex >= 12)
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++du;
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if (programIndex >= 8)
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++dv;
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}
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// Now loop over all of the pixels, stepping in x and y as calculated
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// above. (Assumes that ny divides y and nx divides x...)
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for (uniform int y = y0; y < y1; y += ny) {
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for (uniform int x = 0; x < w; x += nx) {
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// Figur out x,y pixel in NDC
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float px = (x + du - (w / 2.0f)) / (w / 2.0f);
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float py = -(y + dv - (h / 2.0f)) / (h / 2.0f);
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float ret = 0.f;
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Ray ray;
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Isect isect;
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ray.org = 0.f;
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// Poor man's perspective projection
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ray.dir.x = px;
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ray.dir.y = py;
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ray.dir.z = -1.0;
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vnormalize(ray.dir);
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isect.t = 1.0e+17;
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isect.hit = 0;
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for (uniform int snum = 0; snum < 3; ++snum)
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ray_sphere_intersect(isect, ray, spheres[snum]);
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ray_plane_intersect(isect, ray, plane);
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// Note use of 'coherent' if statement; the set of rays we
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// trace will often all hit or all miss the scene
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cif (isect.hit)
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ret = ambient_occlusion(isect, plane, spheres, rngstate);
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// This is a little grungy; we have results for
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// programCount-worth of values. Because we're doing 2x2
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// subsamples, we need to peel them off in groups of four,
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// average the four values for each pixel, and update the
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// output image.
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//
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// Store the varying value to a uniform array of the same size.
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// See the discussion about communication among program
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// instances in the ispc user's manual for more discussion on
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// this idiom.
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uniform float retArray[programCount];
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retArray[programIndex] = ret;
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// offset to the first pixel in the image
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uniform int offset = 3 * (y * w + x);
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for (uniform int p = 0; p < programCount; p += 4, ++offset) {
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// Get the four sample values for this pixel
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uniform float sumret = retArray[p] + retArray[p+1] + retArray[p+2] +
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retArray[p+3];
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// Normalize by number of samples taken
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sumret /= nsubsamples * nsubsamples;
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// Store result in the image
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image[offset+0] = sumret;
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image[offset+1] = sumret;
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image[offset+2] = sumret;
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}
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}
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}
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}
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export void ao_ispc(uniform int w, uniform int h, uniform int nsubsamples,
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uniform float image[]) {
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ao_scanlines(0, h, w, h, nsubsamples, image);
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}
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