/*******************************************************************************
* Procedure: radian_direction
* Purpose: To compute a direction of the gradient image from component dx and
* dy images. Because not all derriviatives are computed in the same way, this
* code allows for dx or dy to have been calculated in different ways.
*
* FOR X: xdirtag = -1 for [-1 0 1]
* xdirtag = 1 for [ 1 0 -1]
*
* FOR Y: ydirtag = -1 for [-1 0 1]'
* ydirtag = 1 for [ 1 0 -1]'
*
* The resulting angle is in radians measured counterclockwise from the
* xdirection. The angle points "up the gradient".
*******************************************************************************/
void radian_direction(short int *delta_x, short int *delta_y, int rows,
int cols, float **dir_radians, int xdirtag, int ydirtag)
{
int r, c, pos;
float *dirim=NULL;
double dx, dy;
/****************************************************************************
* Allocate an image to store the direction of the gradient.
****************************************************************************/
if((dirim = (float *) calloc(rows*cols, sizeof(float))) == NULL){
fprintf(stderr, "Error allocating the gradient direction image.\n");
exit(1);
}
*dir_radians = dirim;
for(r=0,pos=0;r<rows;r++){
for(c=0;c<cols;c++,pos++){
dx = (double)delta_x[pos];
dy = (double)delta_y[pos];
if(xdirtag == 1) dx = -dx;
if(ydirtag == -1) dy = -dy;
dirim[pos] = (float)angle_radians(dx, dy);
}
}
}
bool physical_object::apply_physics(double aElapsedTime, const vec3& aForce)
{
auto ax = angle_radians()[0];
auto ay = angle_radians()[1];
auto az = angle_radians()[2];
auto rotation = [ax, ay, az]() -> mat33
{
if (ax != 0.0 || ay != 0.0)
{
mat33 rx = { { 1.0, 0.0, 0.0 },{ 0.0, std::cos(ax), -std::sin(ax) },{ 0.0, std::sin(ax), std::cos(ax) } };
mat33 ry = { { std::cos(ay), 0.0, std::sin(ay) },{ 0.0, 1.0, 0.0 },{ -std::sin(ay), 0.0, std::cos(ay) } };
mat33 rz = { { std::cos(az), -std::sin(az), 0.0 },{ std::sin(az), std::cos(az), 0.0 },{ 0.0, 0.0, 1.0 } };
return rz * ry * rx;
}
else
{
return mat33{ { std::cos(az), -std::sin(az), 0.0 },{ std::sin(az), std::cos(az), 0.0 },{ 0.0, 0.0, 1.0 } };
}
}();
next_physics().iVelocity = current_physics().iVelocity + ((current_physics().iMass == 0 ? vec3{} : aForce / current_physics().iMass) + (rotation * current_physics().iAcceleration)) * vec3(aElapsedTime, aElapsedTime, aElapsedTime); // v = u + at
next_physics().iPosition = current_physics().iPosition + vec3(1.0, 1.0, 1.0) * (current_physics().iVelocity * aElapsedTime + ((next_physics().iVelocity - current_physics().iVelocity) * aElapsedTime / 2.0));
next_physics().iAngle = (current_physics().iAngle + current_physics().iSpin * aElapsedTime) % (2.0 * boost::math::constants::pi<scalar>());
return next_physics().iPosition != current_physics().iPosition || next_physics().iAngle != current_physics().iAngle;
}
