mirror of
https://github.com/kevinbentley/Descent3.git
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91 lines
2.9 KiB
C++
91 lines
2.9 KiB
C++
/*
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* Descent 3
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* Copyright (C) 2024 Parallax Software
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "3d.h"
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#include "HardwareInternal.h"
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#include <string.h>
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struct InstanceContext {
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matrix m_viewMatrix; // matrix
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matrix m_unscaledMatrix; // unscaled matrix
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vector m_viewPosition; // position
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float m_modelView[4][4]; // model/view transform
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};
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#define MAX_INSTANCE_DEPTH 30
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static InstanceContext sInstanceStack[MAX_INSTANCE_DEPTH];
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static int sInstanceDepth = 0;
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// instance at specified point with specified orientation
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void g3_StartInstanceMatrix(vector *pos, matrix *orient) {
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ASSERT(orient != NULL);
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ASSERT(sInstanceDepth < MAX_INSTANCE_DEPTH);
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sInstanceStack[sInstanceDepth].m_viewMatrix = View_matrix;
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sInstanceStack[sInstanceDepth].m_viewPosition = View_position;
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sInstanceStack[sInstanceDepth].m_unscaledMatrix = Unscaled_matrix;
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memcpy(sInstanceStack[sInstanceDepth].m_modelView, gTransformModelView, sizeof(gTransformModelView));
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++sInstanceDepth;
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// step 1: subtract object position from view position
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vector tempv = View_position - *pos;
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// step 2: rotate view vector through object matrix
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View_position = tempv * *orient;
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// step 3: rotate object matrix through view_matrix (vm = ob * vm)
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matrix tempm, tempm2 = ~*orient;
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tempm = tempm2 * View_matrix;
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View_matrix = tempm;
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tempm = tempm2 * Unscaled_matrix;
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Unscaled_matrix = tempm;
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// transform the model/view matrix
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g3_GetModelViewMatrix(&View_position, &Unscaled_matrix, (float *)gTransformModelView);
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g3_UpdateFullTransform();
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}
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// instance at specified point with specified orientation
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void g3_StartInstanceAngles(vector *pos, angvec *angles) {
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if (angles == NULL) {
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matrix ident;
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vm_MakeIdentity(&ident);
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g3_StartInstanceMatrix(pos, &ident);
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return;
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}
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matrix tm;
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vm_AnglesToMatrix(&tm, angles->p, angles->h, angles->b);
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g3_StartInstanceMatrix(pos, &tm);
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}
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// pops the old context
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void g3_DoneInstance() {
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--sInstanceDepth;
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ASSERT(sInstanceDepth >= 0);
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View_position = sInstanceStack[sInstanceDepth].m_viewPosition;
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View_matrix = sInstanceStack[sInstanceDepth].m_viewMatrix;
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Unscaled_matrix = sInstanceStack[sInstanceDepth].m_unscaledMatrix;
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memcpy(gTransformModelView, sInstanceStack[sInstanceDepth].m_modelView, sizeof(gTransformModelView));
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g3_UpdateFullTransform();
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}
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