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Added function for building frustum planes from view projection matrix.

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This commit is contained in:
Branimir Karadžić 2016-02-10 21:02:00 -08:00
parent 76ccf9d409
commit 4707ebe8ef
2 changed files with 102 additions and 0 deletions
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96
examples/common/bounds.cpp
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@ -277,6 +277,102 @@ void calcMinBoundingSphere(Sphere& _sphere, const void* _vertices, uint32_t _num
_sphere.m_radius = bx::fsqrt(maxDistSq);
}
void buildFrustumPlanes(Plane* _result, const float* _viewProj)
{
const float xw = _viewProj[ 3];
const float yw = _viewProj[ 7];
const float zw = _viewProj[11];
const float ww = _viewProj[15];
const float xz = _viewProj[ 2];
const float yz = _viewProj[ 6];
const float zz = _viewProj[10];
const float wz = _viewProj[14];
Plane& near = _result[0];
Plane& far = _result[1];
Plane& left = _result[2];
Plane& right = _result[3];
Plane& top = _result[4];
Plane& bottom = _result[5];
near.m_normal[0] = xw - xz;
near.m_normal[1] = yw - yz;
near.m_normal[2] = zw - zz;
near.m_dist = ww - wz;
far.m_normal[0] = xw + xz;
far.m_normal[1] = yw + yz;
far.m_normal[2] = zw + zz;
far.m_dist = ww + wz;
const float xx = _viewProj[ 0];
const float yx = _viewProj[ 4];
const float zx = _viewProj[ 8];
const float wx = _viewProj[12];
left.m_normal[0] = xw - xx;
left.m_normal[1] = yw - yx;
left.m_normal[2] = zw - zx;
left.m_dist = ww - wx;
right.m_normal[0] = xw + xx;
right.m_normal[1] = yw + yx;
right.m_normal[2] = zw + zx;
right.m_dist = ww + wx;
const float xy = _viewProj[ 1];
const float yy = _viewProj[ 5];
const float zy = _viewProj[ 9];
const float wy = _viewProj[13];
top.m_normal[0] = xw + xy;
top.m_normal[1] = yw + yy;
top.m_normal[2] = zw + zy;
top.m_dist = ww + wy;
bottom.m_normal[0] = xw - xy;
bottom.m_normal[1] = yw - yy;
bottom.m_normal[2] = zw - zy;
bottom.m_dist = ww - wy;
Plane* plane = _result;
for (uint32_t ii = 0; ii < 6; ++ii)
{
float invLen = 1.0f / bx::vec3Norm(plane->m_normal, plane->m_normal);
plane->m_dist *= invLen;
++plane;
}
}
void intersectPlanes(float _result[3], const Plane& _pa, const Plane& _pb, const Plane& _pc)
{
float axb[3];
bx::vec3Cross(axb, _pa.m_normal, _pb.m_normal);
float bxc[3];
bx::vec3Cross(bxc, _pb.m_normal, _pc.m_normal);
float cxa[3];
bx::vec3Cross(cxa, _pc.m_normal, _pa.m_normal);
float tmp0[3];
bx::vec3Mul(tmp0, bxc, _pa.m_dist);
float tmp1[3];
bx::vec3Mul(tmp1, cxa, _pb.m_dist);
float tmp2[3];
bx::vec3Mul(tmp2, axb, _pc.m_dist);
float tmp[3];
bx::vec3Add(tmp, tmp0, tmp1);
bx::vec3Add(tmp0, tmp, tmp2);
float denom = bx::vec3Dot(_pa.m_normal, bxc);
bx::vec3Mul(_result, tmp0, -1.0f/denom);
}
Ray makeRay(float _x, float _y, const float* _invVp)
{
Ray ray;

6
examples/common/bounds.h
View file

@ -94,6 +94,12 @@ void calcMaxBoundingSphere(Sphere& _sphere, const void* _vertices, uint32_t _num
/// Calculate minimum bounding sphere.
void calcMinBoundingSphere(Sphere& _sphere, const void* _vertices, uint32_t _numVertices, uint32_t _stride, float _step = 0.01f);
/// Returns 6 (near, far, left, right, top, bottom) planes representing frustum planes.
void buildFrustumPlanes(Plane* _planes, const float* _viewProj);
/// Returns point from 3 intersecting planes.
void intersectPlanes(float _result[3], const Plane& _pa, const Plane& _pb, const Plane& _pc);
/// Make screen space ray from x, y coordinate and inverse view-projection matrix.
Ray makeRay(float _x, float _y, const float* _invVp);