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diff --git a/src/VBox/GuestHost/OpenGL/util/bbox.c b/src/VBox/GuestHost/OpenGL/util/bbox.c
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+/* Copyright (c) 2001, Stanford University
+ * All rights reserved
+ *
+ * See the file LICENSE.txt for information on redistributing this software.
+ */
+
+#include <float.h>
+#include "cr_bbox.h"
+
+/**
+ * \mainpage Util
+ *
+ * \section UtilIntroduction Introduction
+ *
+ * Chromium consists of all the top-level files in the cr
+ * directory. The util module basically takes care of API dispatch,
+ * and OpenGL state management.
+ *
+ */
+static float _vmult(const float *m, float x, float y, float z)
+{
+ return m[0]*x + m[4]*y + m[8]*z + m[12];
+}
+
+void
+crTransformBBox( float xmin, float ymin, float zmin,
+ float xmax, float ymax, float zmax,
+ const CRmatrix *m,
+ float *out_xmin, float *out_ymin, float *out_zmin,
+ float *out_xmax, float *out_ymax, float *out_zmax )
+{
+ float x[8], y[8], z[8], w[8];
+ int i,j;
+
+ /* Here is the arrangement of the bounding box
+ *
+ * 0 --- 1
+ * |\ .\
+ * | 2 --- 3
+ * | | . |
+ * | | . |
+ * 4.|...5 |
+ * \| .|
+ * 6 --- 7
+ *
+ * c array contains the edge connectivity list
+ */
+
+ static const int c[8][3] = {
+ {1, 2, 4},
+ {0, 3, 5},
+ {0, 3, 6},
+ {1, 2, 7},
+ {0, 5, 6},
+ {1, 4, 7},
+ {2, 4, 7},
+ {3, 5, 6}
+ };
+
+ x[0] = _vmult(&(m->m00), xmin, ymin, zmin);
+ x[1] = _vmult(&(m->m00), xmax, ymin, zmin);
+ x[2] = _vmult(&(m->m00), xmin, ymax, zmin);
+ x[3] = _vmult(&(m->m00), xmax, ymax, zmin);
+ x[4] = _vmult(&(m->m00), xmin, ymin, zmax);
+ x[5] = _vmult(&(m->m00), xmax, ymin, zmax);
+ x[6] = _vmult(&(m->m00), xmin, ymax, zmax);
+ x[7] = _vmult(&(m->m00), xmax, ymax, zmax);
+
+ y[0] = _vmult(&(m->m01), xmin, ymin, zmin);
+ y[1] = _vmult(&(m->m01), xmax, ymin, zmin);
+ y[2] = _vmult(&(m->m01), xmin, ymax, zmin);
+ y[3] = _vmult(&(m->m01), xmax, ymax, zmin);
+ y[4] = _vmult(&(m->m01), xmin, ymin, zmax);
+ y[5] = _vmult(&(m->m01), xmax, ymin, zmax);
+ y[6] = _vmult(&(m->m01), xmin, ymax, zmax);
+ y[7] = _vmult(&(m->m01), xmax, ymax, zmax);
+
+ z[0] = _vmult(&(m->m02), xmin, ymin, zmin);
+ z[1] = _vmult(&(m->m02), xmax, ymin, zmin);
+ z[2] = _vmult(&(m->m02), xmin, ymax, zmin);
+ z[3] = _vmult(&(m->m02), xmax, ymax, zmin);
+ z[4] = _vmult(&(m->m02), xmin, ymin, zmax);
+ z[5] = _vmult(&(m->m02), xmax, ymin, zmax);
+ z[6] = _vmult(&(m->m02), xmin, ymax, zmax);
+ z[7] = _vmult(&(m->m02), xmax, ymax, zmax);
+
+ w[0] = _vmult(&(m->m03), xmin, ymin, zmin);
+ w[1] = _vmult(&(m->m03), xmax, ymin, zmin);
+ w[2] = _vmult(&(m->m03), xmin, ymax, zmin);
+ w[3] = _vmult(&(m->m03), xmax, ymax, zmin);
+ w[4] = _vmult(&(m->m03), xmin, ymin, zmax);
+ w[5] = _vmult(&(m->m03), xmax, ymin, zmax);
+ w[6] = _vmult(&(m->m03), xmin, ymax, zmax);
+ w[7] = _vmult(&(m->m03), xmax, ymax, zmax);
+
+ /* Now, the object-space bbox has been transformed into
+ * clip-space. */
+
+ /* Find the 2D bounding box of the 3D bounding box */
+ xmin = ymin = zmin = FLT_MAX;
+ xmax = ymax = zmax = -FLT_MAX;
+
+ for (i=0; i<8; i++)
+ {
+ float xp = x[i];
+ float yp = y[i];
+ float zp = z[i];
+ float wp = w[i];
+
+ /* If corner is to be clipped... */
+ if (zp < -wp)
+ {
+
+ /* Point has three edges */
+ for (j=0; j<3; j++)
+ {
+ /* Handle the clipping... */
+ int k = c[i][j];
+ float xk = x[k];
+ float yk = y[k];
+ float zk = z[k];
+ float wk = w[k];
+ float t;
+
+ if (zp+wp-zk-wk == 0.0)
+ continue; /* avoid divide by zero */
+ else
+ t = (wp + zp) / (zp+wp-zk-wk);
+
+ if (t < 0.0f || t > 1.0f)
+ {
+ continue;
+ }
+ wp = wp + (wk-wp) * t;
+ xp = xp + (xk-xp) * t;
+ yp = yp + (yk-yp) * t;
+ zp = -wp;
+
+ xp /= wp;
+ yp /= wp;
+ zp /= wp;
+
+ if (xp < xmin) xmin = xp;
+ if (xp > xmax) xmax = xp;
+ if (yp < ymin) ymin = yp;
+ if (yp > ymax) ymax = yp;
+ if (zp < zmin) zmin = zp;
+ if (zp > zmax) zmax = zp;
+ }
+ }
+ else
+ {
+ /* corner was not clipped.. */
+ xp /= wp;
+ yp /= wp;
+ zp /= wp;
+ if (xp < xmin) xmin = xp;
+ if (xp > xmax) xmax = xp;
+ if (yp < ymin) ymin = yp;
+ if (yp > ymax) ymax = yp;
+ if (zp < zmin) zmin = zp;
+ if (zp > zmax) zmax = zp;
+ }
+ }
+
+ /* Copy for export */
+ if (out_xmin) *out_xmin = xmin;
+ if (out_ymin) *out_ymin = ymin;
+ if (out_zmin) *out_zmin = zmin;
+ if (out_xmax) *out_xmax = xmax;
+ if (out_ymax) *out_ymax = ymax;
+ if (out_zmax) *out_zmax = zmax;
+}
+
+/**
+ * Given the coordinates of the two opposite corners of a bounding box
+ * in object space (x1,y1,z1) and (x2,y2,z2), use the given modelview
+ * and projection matrices to transform the coordinates to NDC space.
+ * Find the 3D bounding bounding box of those eight coordinates and
+ * return the min/max in (x1,y1,x1) and (x2,y2,z2).
+ */
+void
+crProjectBBox(const GLfloat modl[16], const GLfloat proj[16],
+ GLfloat *x1, GLfloat *y1, GLfloat *z1,
+ GLfloat *x2, GLfloat *y2, GLfloat *z2)
+{
+ CRmatrix m;
+
+ /* compute product of modl and proj matrices */
+ m.m00 = proj[0] * modl[0] + proj[4] * modl[1] + proj[8] * modl[2] + proj[12] * modl[3];
+ m.m01 = proj[1] * modl[0] + proj[5] * modl[1] + proj[9] * modl[2] + proj[13] * modl[3];
+ m.m02 = proj[2] * modl[0] + proj[6] * modl[1] + proj[10] * modl[2] + proj[14] * modl[3];
+ m.m03 = proj[3] * modl[0] + proj[7] * modl[1] + proj[11] * modl[2] + proj[15] * modl[3];
+ m.m10 = proj[0] * modl[4] + proj[4] * modl[5] + proj[8] * modl[6] + proj[12] * modl[7];
+ m.m11 = proj[1] * modl[4] + proj[5] * modl[5] + proj[9] * modl[6] + proj[13] * modl[7];
+ m.m12 = proj[2] * modl[4] + proj[6] * modl[5] + proj[10] * modl[6] + proj[14] * modl[7];
+ m.m13 = proj[3] * modl[4] + proj[7] * modl[5] + proj[11] * modl[6] + proj[15] * modl[7];
+ m.m20 = proj[0] * modl[8] + proj[4] * modl[9] + proj[8] * modl[10] + proj[12] * modl[11];
+ m.m21 = proj[1] * modl[8] + proj[5] * modl[9] + proj[9] * modl[10] + proj[13] * modl[11];
+ m.m22 = proj[2] * modl[8] + proj[6] * modl[9] + proj[10] * modl[10] + proj[14] * modl[11];
+ m.m23 = proj[3] * modl[8] + proj[7] * modl[9] + proj[11] * modl[10] + proj[15] * modl[11];
+ m.m30 = proj[0] * modl[12] + proj[4] * modl[13] + proj[8] * modl[14] + proj[12] * modl[15];
+ m.m31 = proj[1] * modl[12] + proj[5] * modl[13] + proj[9] * modl[14] + proj[13] * modl[15];
+ m.m32 = proj[2] * modl[12] + proj[6] * modl[13] + proj[10] * modl[14] + proj[14] * modl[15];
+ m.m33 = proj[3] * modl[12] + proj[7] * modl[13] + proj[11] * modl[14] + proj[15] * modl[15];
+
+ crTransformBBox( *x1, *y1, *z1,
+ *x2, *y2, *z2,
+ &m,
+ x1, y1, z1,
+ x2, y2, z2 );
+}
+
+
+#define MIN(a, b) ((a) < (b) ? (a) : (b))
+#define MAX(a, b) ((a) > (b) ? (a) : (b))
+
+
+/**
+ * Compute union of a and b and put in result.
+ */
+void
+crRectiUnion(CRrecti *result, const CRrecti *a, const CRrecti *b)
+{
+ result->x1 = MIN(a->x1, b->x1);
+ result->x2 = MAX(a->x2, b->x2);
+ result->y1 = MIN(a->y1, b->y1);
+ result->y2 = MAX(a->y2, b->y2);
+}
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