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Matt Pharr
273
examples/rt/rt.ispc
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273
examples/rt/rt.ispc
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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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#define bool int
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typedef float<3> float3;
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struct Ray {
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float3 origin, dir, invDir;
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uniform unsigned int dirIsNeg[3];
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float mint, maxt;
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int hitId;
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};
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struct Triangle {
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uniform float3 p[3];
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uniform int id;
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};
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struct LinearBVHNode {
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uniform float3 bounds[2];
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uniform unsigned int offset; // num primitives for leaf, second child for interior
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uniform unsigned int primsAxis; // 0:7 nPrimitives, 8:15 split axis, 16:31 padding
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};
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static inline uniform int nPrims(const reference LinearBVHNode node) {
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return (node.primsAxis & 0xff);
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}
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static inline uniform int axis(const reference LinearBVHNode node) {
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return ((node.primsAxis >> 8) & 0xff);
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}
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static inline uniform bool isInterior(const reference LinearBVHNode node) {
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return nPrims(node) == 0;
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}
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static inline float3 Cross(const float3 v1, const float3 v2) {
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float v1x = v1.x, v1y = v1.y, v1z = v1.z;
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float v2x = v2.x, v2y = v2.y, v2z = v2.z;
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float3 ret;
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ret.x = (v1y * v2z) - (v1z * v2y);
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ret.y = (v1z * v2x) - (v1x * v2z);
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ret.z = (v1x * v2y) - (v1y * v2x);
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return ret;
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}
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static inline float Dot(const float3 a, const float3 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 void generateRay(uniform const float raster2camera[4][4],
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uniform const float camera2world[4][4],
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float x, float y, reference Ray ray) {
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ray.mint = 0.f;
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ray.maxt = 1e30f;
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ray.hitId = 0;
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// transform raster coordinate (x, y, 0) to camera space
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float camx = raster2camera[0][0] * x + raster2camera[0][1] * y + raster2camera[0][3];
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float camy = raster2camera[1][0] * x + raster2camera[1][1] * y + raster2camera[1][3];
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float camz = raster2camera[2][3];
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float camw = raster2camera[3][3];
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camx /= camw;
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camy /= camw;
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camz /= camw;
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ray.dir.x = camera2world[0][0] * camx + camera2world[0][1] * camy + camera2world[0][2] * camz;
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ray.dir.y = camera2world[1][0] * camx + camera2world[1][1] * camy + camera2world[1][2] * camz;
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ray.dir.z = camera2world[2][0] * camx + camera2world[2][1] * camy + camera2world[2][2] * camz;
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ray.origin.x = camera2world[0][3] / camera2world[3][3];
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ray.origin.y = camera2world[1][3] / camera2world[3][3];
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ray.origin.z = camera2world[2][3] / camera2world[3][3];
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ray.invDir = 1.f / ray.dir;
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ray.dirIsNeg[0] = any(ray.invDir.x < 0) ? 1 : 0;
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ray.dirIsNeg[1] = any(ray.invDir.y < 0) ? 1 : 0;
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ray.dirIsNeg[2] = any(ray.invDir.z < 0) ? 1 : 0;
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}
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static inline bool BBoxIntersect(const reference uniform float3 bounds[2],
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const reference Ray ray) {
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float t0 = ray.mint, t1 = ray.maxt;
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// Check all three axis-aligned slabs. Don't try to early out; it's
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// not worth the trouble
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float3 tNear = (bounds[0] - ray.origin) * ray.invDir;
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float3 tFar = (bounds[1] - ray.origin) * ray.invDir;
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if (tNear.x > tFar.x) {
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float tmp = tNear.x;
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tNear.x = tFar.x;
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tFar.x = tmp;
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}
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t0 = max(tNear.x, t0);
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t1 = min(tFar.x, t1);
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if (tNear.y > tFar.y) {
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float tmp = tNear.y;
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tNear.y = tFar.y;
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tFar.y = tmp;
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}
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t0 = max(tNear.y, t0);
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t1 = min(tFar.y, t1);
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if (tNear.z > tFar.z) {
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float tmp = tNear.z;
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tNear.z = tFar.z;
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tFar.z = tmp;
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}
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t0 = max(tNear.z, t0);
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t1 = min(tFar.z, t1);
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return (t0 <= t1);
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}
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static inline bool TriIntersect(const reference Triangle tri, reference Ray ray) {
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uniform float3 e1 = tri.p[1] - tri.p[0];
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uniform float3 e2 = tri.p[2] - tri.p[0];
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float3 s1 = Cross(ray.dir, e2);
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float divisor = Dot(s1, e1);
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bool hit = true;
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if (divisor == 0.)
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hit = false;
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float invDivisor = 1.f / divisor;
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// Compute first barycentric coordinate
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float3 d = ray.origin - tri.p[0];
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float b1 = Dot(d, s1) * invDivisor;
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if (b1 < 0. || b1 > 1.)
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hit = false;
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// Compute second barycentric coordinate
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float3 s2 = Cross(d, e1);
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float b2 = Dot(ray.dir, s2) * invDivisor;
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if (b2 < 0. || b1 + b2 > 1.)
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hit = false;
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// Compute _t_ to intersection point
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float t = Dot(e2, s2) * invDivisor;
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if (t < ray.mint || t > ray.maxt)
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hit = false;
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if (hit) {
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ray.maxt = t;
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ray.hitId = tri.id;
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}
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return hit;
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}
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bool BVHIntersect(const LinearBVHNode nodes[], const Triangle tris[],
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reference Ray r) {
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Ray ray = r;
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bool hit = false;
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// Follow ray through BVH nodes to find primitive intersections
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uniform int todoOffset = 0, nodeNum = 0;
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uniform int todo[64];
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while (true) {
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// Check ray against BVH node
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LinearBVHNode node = nodes[nodeNum];
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if (any(BBoxIntersect(node.bounds, ray))) {
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uniform unsigned int nPrimitives = nPrims(node);
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if (nPrimitives > 0) {
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// Intersect ray with primitives in leaf BVH node
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uniform unsigned int primitivesOffset = node.offset;
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for (uniform unsigned int i = 0; i < nPrimitives; ++i) {
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if (TriIntersect(tris[primitivesOffset+i], ray))
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hit = true;
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}
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if (todoOffset == 0)
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break;
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nodeNum = todo[--todoOffset];
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}
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else {
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// Put far BVH node on _todo_ stack, advance to near node
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if (r.dirIsNeg[axis(node)]) {
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todo[todoOffset++] = nodeNum + 1;
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nodeNum = node.offset;
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}
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else {
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todo[todoOffset++] = node.offset;
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nodeNum = nodeNum + 1;
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}
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}
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}
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else {
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if (todoOffset == 0)
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break;
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nodeNum = todo[--todoOffset];
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}
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}
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r.maxt = ray.maxt;
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r.hitId = ray.hitId;
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return hit;
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}
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export void raytrace(uniform int width, uniform int height,
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const uniform float raster2camera[4][4],
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const uniform float camera2world[4][4],
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uniform float image[], uniform int id[],
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const LinearBVHNode nodes[],
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const Triangle triangles[]) {
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static const uniform float udx[16] = { 0, 1, 0, 1, 2, 3, 2, 3,
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0, 1, 0, 1, 2, 3, 2, 3 };
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static const uniform float udy[16] = { 0, 0, 1, 1, 0, 0, 1, 1,
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2, 2, 3, 3, 2, 2, 3, 3 };
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// The outer loops are always over blocks of 4x4 pixels
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for (uniform int y = 0; y < height; y += 4) {
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for (uniform int x = 0; x < width; x += 4) {
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// Now we have a block of 4x4=16 pixels to process; it will
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// take 16/programCount iterations of this loop to process
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// them.
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for (uniform int o = 0; o < 16 / programCount; ++o) {
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// Map program instances to samples in the udx/udy arrays
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// to figure out which pixel each program instance is
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// responsible for
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const float dx = udx[o * programCount + programIndex];
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const float dy = udy[o * programCount + programIndex];
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Ray ray;
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generateRay(raster2camera, camera2world, x+dx, y+dy, ray);
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BVHIntersect(nodes, triangles, ray);
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int offset = (y + (int)dy) * width + (x + (int)dx);
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image[offset] = ray.maxt;
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id[offset] = ray.hitId;
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}
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}
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}
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}
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