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Revert "engine.cpp/.h: clean up & fix lintersect(). Additionally, add support for finding intersections of collinear line segments."
This reverts r6886. git-svn-id: https://svn.eduke32.com/eduke32@7290 1a8010ca-5511-0410-912e-c29ae57300e0
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terminx
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2 changed files with 48 additions and 69 deletions
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@ -1230,10 +1230,8 @@ int32_t sectorofwall_noquick(int16_t wallNum);
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int32_t loopnumofsector(int16_t sectnum, int16_t wallnum);
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void setslope(int32_t sectnum, int32_t cf, int16_t slope);
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int32_t lintersect(int32_t originX, int32_t originY, int32_t originZ,
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int32_t destX, int32_t destY, int32_t destZ,
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int32_t lineStartX, int32_t lineStartY, int32_t lineEndX, int32_t lineEndY,
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int32_t *intersectionX, int32_t *intersectionY, int32_t *intersectionZ);
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int32_t lintersect(int32_t x1, int32_t y1, int32_t z1, int32_t x2, int32_t y2, int32_t z2, int32_t x3,
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int32_t y3, int32_t x4, int32_t y4, int32_t *intx, int32_t *inty, int32_t *intz);
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int32_t rayintersect(int32_t x1, int32_t y1, int32_t z1, int32_t vx, int32_t vy, int32_t vz, int32_t x3,
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int32_t y3, int32_t x4, int32_t y4, int32_t *intx, int32_t *inty, int32_t *intz);
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@ -7369,75 +7369,56 @@ int32_t changespritestat(int16_t spritenum, int16_t newstatnum)
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//
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// lintersect (internal)
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//
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int32_t lintersect(const int32_t originX, const int32_t originY, const int32_t originZ,
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const int32_t destX, const int32_t destY, const int32_t destZ,
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const int32_t lineStartX, const int32_t lineStartY, const int32_t lineEndX, const int32_t lineEndY,
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int32_t *intersectionX, int32_t *intersectionY, int32_t *intersectionZ)
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int32_t lintersect(int32_t x1, int32_t y1, int32_t z1,
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int32_t x2, int32_t y2, int32_t z2,
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int32_t x3, int32_t y3, int32_t x4, int32_t y4,
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int32_t *intx, int32_t *inty, int32_t *intz)
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{
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const vec2_t ray = { destX-originX,
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destY-originY };
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const vec2_t lineVec = { lineEndX-lineStartX,
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lineEndY-lineStartY };
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const vec2_t originDiff = { lineStartX-originX,
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lineStartY-originY };
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// p1 to p2 is a line segment
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int32_t const x21 = x2 - x1;
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int32_t const x34 = x3 - x4;
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int32_t const y21 = y2 - y1;
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int32_t const y34 = y3 - y4;
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int32_t const bot = x21 * y34 - y21 * x34;
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int32_t topt;
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const int32_t rayCrossLineVec = ray.x*lineVec.y - ray.y*lineVec.x;
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const int32_t originDiffCrossRay = originDiff.x*ray.y - originDiff.y*ray.x;
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if (rayCrossLineVec == 0)
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{
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if (originDiffCrossRay != 0)
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{
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// line segments are parallel
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return 0;
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}
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// line segments are collinear
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const int32_t rayLengthSquared = ray.x*ray.x + ray.y*ray.y;
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const int32_t rayDotOriginDiff = ray.x*originDiff.x + ray.y*originDiff.y;
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const int32_t rayDotLineEndDiff = rayDotOriginDiff + ray.x*lineVec.x + ray.y*lineVec.y;
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int32_t t = min(rayDotOriginDiff, rayDotLineEndDiff);
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if (rayDotOriginDiff < 0)
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{
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if (rayDotLineEndDiff < 0)
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return 0;
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t = 0;
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}
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else if (rayDotOriginDiff > rayLengthSquared)
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{
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if (rayDotLineEndDiff > rayLengthSquared)
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return 0;
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t = rayDotLineEndDiff;
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}
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t = divscale24(t, rayLengthSquared);
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*intersectionX = originX + mulscale24(ray.x, t);
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*intersectionY = originY + mulscale24(ray.y, t);
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*intersectionZ = originZ + mulscale24(destZ-originZ, t);
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return 1;
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}
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const int32_t originDiffCrossLineVec = originDiff.x*lineVec.y - originDiff.y*lineVec.x;
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static const int32_t signBit = 1u<<31u;
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// t is < 0 if (originDiffCrossLineVec^rayCrossLineVec) & signBit)
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// t is > 1 if originDiffCrossLineVec > rayCrossLineVec
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// u is < 0 if (originDiffCrossRay^rayCrossLineVec) & signBit
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// u is > 1 if originDiffCrossRay > rayCrossLineVec
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// where int32_t u = divscale24(originDiffCrossRay, rayCrossLineVec);
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if (originDiffCrossLineVec > rayCrossLineVec ||
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originDiffCrossRay > rayCrossLineVec ||
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((originDiffCrossLineVec^rayCrossLineVec) & signBit) ||
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((originDiffCrossRay^rayCrossLineVec) & signBit))
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{
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// line segments do not overlap
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if (bot == 0)
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return 0;
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else if (bot > 0)
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{
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int32_t x31 = x3 - x1;
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int32_t y31 = y3 - y1;
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topt = x31 * y34 - y31 * x34;
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if ((unsigned)topt >= (unsigned)bot)
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return 0;
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int32_t topu = x21 * y31 - y21 * x31;
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if ((unsigned)topu >= (unsigned)bot)
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return 0;
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}
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int32_t t = divscale24(originDiffCrossLineVec, rayCrossLineVec);
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*intersectionX = originX + mulscale24(ray.x, t);
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*intersectionY = originY + mulscale24(ray.y, t);
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*intersectionZ = originZ + mulscale24(destZ-originZ, t);
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else
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{
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int32_t x31 = x3 - x1;
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int32_t y31 = y3 - y1;
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topt = x31 * y34 - y31 * x34;
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if ((unsigned)topt <= (unsigned)bot)
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return 0;
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int32_t topu = x21 * y31 - y21 * x31;
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if ((unsigned)topu <= (unsigned)bot)
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return 0;
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}
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int32_t t = divscale24(topt, bot);
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*intx = x1 + mulscale24(x21, t);
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*inty = y1 + mulscale24(y21, t);
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*intz = z1 + mulscale24(z2 - z1, t);
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return 1;
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}
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