/*
* This file is part of the DXX-Rebirth project <https://www.dxx-rebirth.com/>.
* It is copyright by its individual contributors, as recorded in the
* project's Git history. See COPYING.txt at the top level for license
* terms and a link to the Git history.
*/
/*
*
* Instancing routines
*
*/
#include <stdlib.h>
#include "dxxerror.h"
#include "3d.h"
#include "globvars.h"
namespace dcx {
namespace {
struct instance_context {
vms_matrix m;
vms_vector p;
};
}
static std::array<instance_context, 5> instance_stack;
int instance_depth = 0;
//instance at specified point with specified orientation
//if matrix==NULL, don't modify matrix. This will be like doing an offset
void g3_start_instance_matrix()
{
auto &s = instance_stack.at(instance_depth++);
s.m = View_matrix;
s.p = View_position;
}
void g3_start_instance_matrix(const vms_vector &pos, const vms_matrix &orient)
{
g3_start_instance_matrix();
//step 1: subtract object position from view position
const auto tempv = vm_vec_sub(View_position, pos);
//step 2: rotate view vector through object matrix
vm_vec_rotate(View_position, tempv, orient);
//step 3: rotate object matrix through view_matrix (vm = ob * vm)
View_matrix = vm_matrix_x_matrix(vm_transposed_matrix(orient), View_matrix);
}
//instance at specified point with specified orientation
//if angles==NULL, don't modify matrix. This will be like doing an offset
void g3_start_instance_angles(const vms_vector &pos, const vms_angvec &angles)
{
const auto &&tm = vm_angles_2_matrix(angles);
g3_start_instance_matrix(pos, tm);
}
//pops the old context
void g3_done_instance()
{
instance_depth--;
Assert(instance_depth >= 0);
View_position = instance_stack[instance_depth].p;
View_matrix = instance_stack[instance_depth].m;
}
}