CydandClaude Opus 4.8
4abbf8879f
Imports the current Win32 source for the pod-racing game 'Red Planet', built on the MUNGA engine and its L4 (Win32/DirectX) platform layer: - MUNGA / MUNGA_L4: cross-platform engine core and Win32 backend - RP / RP_L4: Red Planet game logic and Win32 application - DivLoader, Setup1: asset loader and installer project - lib, MUNGA_L4/openal, MUNGA_L4/sos: third-party audio dependencies Removed stale Subversion metadata and added .gitignore/.gitattributes. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
465 lines
13 KiB
C++
465 lines
13 KiB
C++
#include "munga.h"
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#pragma hdrstop
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#include "boxsolid.h"
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#include "line.h"
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//#############################################################################
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//############################### BoxedCone #############################
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//#############################################################################
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//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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//
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BoxedCone::BoxedCone(
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const ExtentBox &extents,
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BoxedSolid::Material material,
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Simulation *owner,
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BoxedSolid *next_solid
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):
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BoxedSolid(extents, ConeType, material, owner, next_solid)
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{
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Check_Pointer(this);
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}
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//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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//
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BoxedCone::~BoxedCone()
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{
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Check_Pointer(this);
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}
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//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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//
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Logical
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BoxedCone::IntersectsBounded(const ExtentBox &extents)
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{
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Check(this);
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Check(&extents);
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Verify(minX <= extents.minX);
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Verify(maxX >= extents.maxX);
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Verify(minY <= extents.minY);
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Verify(maxY >= extents.maxY);
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Verify(minZ <= extents.minZ);
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Verify(maxZ >= extents.maxZ);
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//
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//------------------------------------------------------------------------
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// Find the center point in the XZ plane of the cone, and find the biggest
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// radius of the cone by measuring in the X axis, along with its height
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//------------------------------------------------------------------------
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//
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Vector3D center;
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center.x = (minX + maxX) * 0.5f;
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center.y = minY;
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center.z = (minZ + maxZ) * 0.5f;
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Scalar radius = maxX - center.x;
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Verify(!Small_Enough(radius));
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//
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//--------------------------------------------------------------------------
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// Convert the closest point in the slice to the coordinates of the cone,
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// putting the apex of the cone at the origin, then make sure that the point
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// isn't in one of the corners of the box
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//--------------------------------------------------------------------------
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//
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Vector3D nearest(center);
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extents.Constrain(&nearest);
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center.y = maxY;
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nearest.Subtract(center,nearest);
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Scalar r = nearest.x*nearest.x + nearest.z*nearest.z;
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if (r > radius*radius)
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{
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return False;
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}
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//
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//--------------------------------------------------------------------------
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// Compute the distance from the axis, and then see if the slope of the line
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// from the cone apex to the test point is less than the slope of the cone
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//--------------------------------------------------------------------------
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//
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r = Sqrt(r);
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Scalar height = maxY - minY;
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return r*height <= nearest.y*radius;
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}
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//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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//
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Logical
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BoxedCone::ContainsBounded(const Point3D &point)
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{
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Check(this);
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Check(&point);
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Verify(minX <= point.x);
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Verify(maxX >= point.x);
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Verify(minY <= point.y);
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Verify(maxY >= point.y);
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Verify(minZ <= point.z);
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Verify(maxZ >= point.z);
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//
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//------------------------------------------------------------------------
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// Find the center point in the XZ plane of the cone, and find the biggest
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// radius of the cone by measuring in the X axis, along with its height
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//------------------------------------------------------------------------
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//
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Vector3D center;
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center.x = (minX + maxX) * 0.5f;
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center.y = maxY;
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center.z = (minZ + maxZ) * 0.5f;
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Scalar radius = maxX - center.x;
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Verify(!Small_Enough(radius));
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//
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//--------------------------------------------------------------------------
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// Convert the closest point in the slice to the coordinates of the cone,
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// putting the apex of the cone at the origin, then make sure that the point
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// isn't in one of the corners of the box
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//--------------------------------------------------------------------------
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//
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Vector3D nearest;
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nearest.Subtract(center, point);
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Scalar r = nearest.x*nearest.x + nearest.z*nearest.z;
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if (r > radius*radius)
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{
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return False;
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}
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//
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//--------------------------------------------------------------------------
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// Compute the distance from the axis, and then see if the slope of the line
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// from the cone apex to the test point is less than the slope of the cone
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//--------------------------------------------------------------------------
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//
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r = Sqrt(r);
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Scalar height = maxY - minY;
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return r*height <= nearest.y*radius;
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}
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//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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//
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Scalar
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BoxedCone::FindDistanceBelowBounded(const Point3D &point)
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{
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Check(this);
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Check(&point);
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Verify(minX <= point.x);
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Verify(maxX >= point.x);
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Verify(minY <= point.y);
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Verify(minZ <= point.z);
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Verify(maxZ >= point.z);
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//
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//------------------------------------------------------------------------
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// Find the center point in the XZ plane of the cone, and find the biggest
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// radius of the cone by measuring in the X axis, along with its height
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//------------------------------------------------------------------------
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//
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Vector3D center;
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center.x = (minX + maxX) * 0.5f;
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center.y = maxY;
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center.z = (minZ + maxZ) * 0.5f;
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Scalar radius = maxX - center.x;
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Verify(!Small_Enough(radius));
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//
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//--------------------------------------------------------------------------
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// Convert the closest point in the slice to the coordinates of the cone,
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// putting the apex of the cone at the origin, then make sure that the point
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// isn't in one of the corners of the box
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//--------------------------------------------------------------------------
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//
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Vector3D nearest;
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nearest.Subtract(point, center);
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Scalar r = nearest.x*nearest.x + nearest.z*nearest.z;
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if (r > radius*radius)
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{
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return -1.0f;
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}
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//
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//--------------------------------------------------------------------------
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// Compute the distance from the axis, and then see if the slope of the line
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// from the cone apex to the test point is less than the slope of the cone
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//--------------------------------------------------------------------------
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//
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r = Sqrt(r);
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Scalar height = maxY - minY;
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nearest.y += r*(height/radius);
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return Max(nearest.y,0.0f);
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}
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//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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//
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// This function is a helper function used in the derivation for the terms of
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// the quadratic equation to find t when colliding a line and a cone. I'm not
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// real clear on the physical representation of this kind of dot product
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//
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static Scalar
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Special_Cone_Dot_Product(
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const Vector3D &v1,
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const Vector3D &v2,
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Scalar squared_tan
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)
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{
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return v1.x*v2.x - squared_tan*v1.y*v2.y + v1.z*v2.z;
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}
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//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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//
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Logical
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BoxedCone::HitByBounded(
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Line *line,
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Scalar enters,
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Scalar leaves
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)
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{
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Check(this);
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Check(line);
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Verify(enters <= leaves);
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Verify(leaves >= 0.0f);
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//
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//--------------------------------------------------------------------------
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// Find out the size of the box, and set up the height and maximum radius of
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// the cone, along with the squared tangent of the spread angle
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//--------------------------------------------------------------------------
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//
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Vector3D center;
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center.x = (minX + maxX) * 0.5f;
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center.y = maxY;
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center.z = (minZ + maxZ) * 0.5f;
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Scalar radius = maxX - center.x;
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Scalar height = maxY - minY;
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Verify(!Small_Enough(height));
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Scalar squared_tan = radius*radius/(height*height);
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//
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//-------------------------------------------------------------------------
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// Find the line between the point of the cone and the origin of our line,
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// then set up the conditions for the quadratic equation. The following
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// equation sets up a*t^2 + b*t + c = 0. The terms a, b, and c are derived
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// by solving the following equations for t:
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//
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// p == line->origin + line->direction * t
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// r == p - cone->apex
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// r.x^2 + r.z^2 == tan^2(cone_angle)*r.y^2
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//
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// The special cone dot product function is a handy way to reduce the
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// complexity of the problem
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//-------------------------------------------------------------------------
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//
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Vector3D v;
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v.Subtract(line->origin,center);
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//
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//--------------------------------------------------------------------------
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// If the line diverges from the axis at the same angle as the spread angle,
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// we need to find the closest point on the line to the axis. We then drop
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// a vertical plane containing the line through the cone at this point, thus
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// generating a hyperbola. We then solve the hyperbola vs. line equation to
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// get our intersection point
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//--------------------------------------------------------------------------
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//
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Scalar a =
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Special_Cone_Dot_Product(line->direction, line->direction, squared_tan);
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if (Small_Enough(a))
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{
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}
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//
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//-----------------------------------------------
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// Otherwise, continue solving the first equation
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//-----------------------------------------------
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//
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else
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{
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Scalar b =
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2.0f * Special_Cone_Dot_Product(v, line->direction, squared_tan);
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Scalar c = Special_Cone_Dot_Product(v, v, squared_tan);
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//
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//-----------------------------------------------------------------------
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// Now, use the quadratic equation to determine where the two points
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// intersect the cone. If there is no solution, than the line missed the
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// cone
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//-----------------------------------------------------------------------
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//
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Verify(!Small_Enough(a));
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Scalar t = -b / (2.0f * a);
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Scalar i = b*b - 4.0f*a*c;
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if (i < 0.0f)
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{
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return False;
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}
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//
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//----------------------------------------------------------------------
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// If the interval is zero, then the line hits the cone in one spot only
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// (a tangential hit). Check to see if hits the lower half of the conic
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// equation (our cone)
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//----------------------------------------------------------------------
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//
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if (Small_Enough(i))
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{
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Scalar y = v.y + line->direction.y * t;
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if (y > 0.0f)
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{
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return False;
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}
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//
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//----------------------------------------------------------------
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// It hit the lower cone, so see if it was entering or leaving the
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// cone
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//----------------------------------------------------------------
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//
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if (line->direction.y > 0.0f)
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{
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//
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//-------------------------------------------------------------
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// The line is leaving the cone, so see if we need to reset the
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// leaving distance
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//-------------------------------------------------------------
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//
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if (t < leaves)
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{
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leaves = t;
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}
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}
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//
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//------------------------------------------------------------
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// The line is entering the cone, so see if we need to set the
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// entering distance
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//------------------------------------------------------------
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//
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else if (t > enters)
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{
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enters = t;
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}
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//
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//-------------------------------------------------------------------
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// See if we still have a collision with the cone, and if so, set the
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// new line length
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//-------------------------------------------------------------------
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//
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if (enters > leaves || enters > line->length || leaves < 0.0f)
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{
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return False;
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}
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line->length = Max(enters, 0.0f);
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return True;
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}
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//
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//----------------------------------------------------------------------
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// If the interval is non-zero, then the conic section was struck in two
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// places. Find out the lengths to those places and the y values for
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// those points
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//----------------------------------------------------------------------
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//
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i = Sqrt(i) / (2.0f * a);
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Scalar t1,t2;
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if (i > 0.0f)
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{
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t1 = t - i;
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t2 = t + i;
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}
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else
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{
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t1 = t + i;
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t2 = t - i;
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}
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Scalar y1 = v.y + line->direction.y * t1;
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Scalar y2 = v.y + line->direction.y * t2;
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//
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//----------------------------------------------------------------------
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// There are four combinations of the signs of the y values. Each has a
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// different effect on missing/hitting, entering or leaving distances.
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// First check to see if only the upper conic was hit
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//----------------------------------------------------------------------
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//
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if (y1 > 0.0f)
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{
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if (y2 > 0.0f)
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{
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return False;
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}
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//
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//-----------------------------------------------------------------
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// The ray is entering our conic, so set the distance appropriately
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//-----------------------------------------------------------------
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//
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if (t2 > enters)
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{
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enters = t2;
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}
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}
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//
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//----------------------------------------------------------------------
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// See if the ray is leaving the lower conic, and if so, set the leaving
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// distance accordingly
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//----------------------------------------------------------------------
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//
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else
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{
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if (y2 > 0.0f)
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{
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if (t1 < leaves)
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{
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leaves = t1;
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}
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}
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//
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//--------------------------------------------------------------------
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// Both spots are in the lower conic, so set both leaving and entering
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// distances
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//--------------------------------------------------------------------
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//
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else
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{
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if (t1 > enters)
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{
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enters = t1;
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}
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if (t2 < leaves)
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{
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leaves = t2;
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}
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}
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}
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//
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//-----------------------------------------------------------------------
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// See if we still have a collision with the cone, and if so, set the new
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// line length
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//-----------------------------------------------------------------------
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//
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if (enters > leaves || enters > line->length || leaves < 0.0f)
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{
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return False;
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}
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line->length = Max(enters, 0.0f);
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}
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return True;
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}
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//~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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//
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Logical
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BoxedCone::TestInstance() const
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{
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return solidType == ConeType;
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}
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