307 lines
7.6 KiB
C
307 lines
7.6 KiB
C
/**
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* Powder Toy - air simulation
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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 <math.h>
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#include <air.h>
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#include <powder.h>
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#include <defines.h>
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#include "gravity.h"
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float kernel[9];
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float vx[YRES/CELL][XRES/CELL], ovx[YRES/CELL][XRES/CELL];
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float vy[YRES/CELL][XRES/CELL], ovy[YRES/CELL][XRES/CELL];
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float pv[YRES/CELL][XRES/CELL], opv[YRES/CELL][XRES/CELL];
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unsigned char bmap_blockair[YRES/CELL][XRES/CELL];
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unsigned char bmap_blockairh[YRES/CELL][XRES/CELL];
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float cb_vx[YRES/CELL][XRES/CELL];
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float cb_vy[YRES/CELL][XRES/CELL];
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float cb_pv[YRES/CELL][XRES/CELL];
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float cb_hv[YRES/CELL][XRES/CELL];
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float fvx[YRES/CELL][XRES/CELL], fvy[YRES/CELL][XRES/CELL];
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float hv[YRES/CELL][XRES/CELL], ohv[YRES/CELL][XRES/CELL]; // For Ambient Heat
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void make_kernel(void) //used for velocity
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{
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int i, j;
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float s = 0.0f;
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for (j=-1; j<2; j++)
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for (i=-1; i<2; i++)
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{
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kernel[(i+1)+3*(j+1)] = expf(-2.0f*(i*i+j*j));
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s += kernel[(i+1)+3*(j+1)];
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}
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s = 1.0f / s;
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for (j=-1; j<2; j++)
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for (i=-1; i<2; i++)
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kernel[(i+1)+3*(j+1)] *= s;
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}
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void update_airh(void)
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{
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int x, y, i, j;
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float odh, dh, dx, dy, f, tx, ty;
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for (i=0; i<YRES/CELL; i++) //reduces pressure/velocity on the edges every frame
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{
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hv[i][0] = 295.15f;
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hv[i][1] = 295.15f;
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hv[i][XRES/CELL-3] = 295.15f;
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hv[i][XRES/CELL-2] = 295.15f;
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hv[i][XRES/CELL-1] = 295.15f;
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}
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for (i=0; i<XRES/CELL; i++) //reduces pressure/velocity on the edges every frame
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{
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hv[0][i] = 295.15f;
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hv[1][i] = 295.15f;
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hv[YRES/CELL-3][i] = 295.15f;
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hv[YRES/CELL-2][i] = 295.15f;
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hv[YRES/CELL-1][i] = 295.15f;
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}
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for (y=0; y<YRES/CELL; y++) //update velocity and pressure
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{
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for (x=0; x<XRES/CELL; x++)
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{
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dh = 0.0f;
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dx = 0.0f;
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dy = 0.0f;
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for (j=-1; j<2; j++)
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{
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for (i=-1; i<2; i++)
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{
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if (y+j>0 && y+j<YRES/CELL-2 &&
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x+i>0 && x+i<XRES/CELL-2 &&
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!bmap_blockairh[y+j][x+i])
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{
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f = kernel[i+1+(j+1)*3];
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dh += hv[y+j][x+i]*f;
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dx += vx[y+j][x+i]*f;
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dy += vy[y+j][x+i]*f;
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}
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else
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{
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f = kernel[i+1+(j+1)*3];
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dh += hv[y][x]*f;
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dx += vx[y][x]*f;
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dy += vy[y][x]*f;
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}
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}
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}
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tx = x - dx*0.7f;
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ty = y - dy*0.7f;
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i = (int)tx;
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j = (int)ty;
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tx -= i;
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ty -= j;
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if (i>=2 && i<XRES/CELL-3 && j>=2 && j<YRES/CELL-3)
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{
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odh = dh;
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dh *= 1.0f - AIR_VADV;
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dh += AIR_VADV*(1.0f-tx)*(1.0f-ty)*(bmap_blockairh[j][i] ? odh : hv[j][i]);
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dh += AIR_VADV*tx*(1.0f-ty)*(bmap_blockairh[j][i+1] ? odh : hv[j][i+1]);
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dh += AIR_VADV*(1.0f-tx)*ty*(bmap_blockairh[j+1][i] ? odh : hv[j+1][i]);
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dh += AIR_VADV*tx*ty*(bmap_blockairh[j+1][i+1] ? odh : hv[j+1][i+1]);
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}
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if(!gravityMode){ //Vertical gravity only for the time being
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float airdiff = dh-hv[y][x];
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pv[y][x] += airdiff/5000.0f;
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if(airdiff>0)
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vy[y][x] -= airdiff/5000.0f;
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}
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ohv[y][x] = dh;
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}
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}
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memcpy(hv, ohv, sizeof(hv));
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}
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void update_air(void)
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{
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int x, y, i, j;
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float dp, dx, dy, f, tx, ty;
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if (airMode != 4) { //airMode 4 is no air/pressure update
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for (i=0; i<YRES/CELL; i++) //reduces pressure/velocity on the edges every frame
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{
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pv[i][0] = pv[i][0]*0.8f;
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pv[i][1] = pv[i][1]*0.8f;
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pv[i][2] = pv[i][2]*0.8f;
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pv[i][XRES/CELL-2] = pv[i][XRES/CELL-2]*0.8f;
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pv[i][XRES/CELL-1] = pv[i][XRES/CELL-1]*0.8f;
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vx[i][0] = vx[i][1]*0.9f;
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vx[i][1] = vx[i][2]*0.9f;
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vx[i][XRES/CELL-2] = vx[i][XRES/CELL-3]*0.9f;
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vx[i][XRES/CELL-1] = vx[i][XRES/CELL-2]*0.9f;
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vy[i][0] = vy[i][1]*0.9f;
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vy[i][1] = vy[i][2]*0.9f;
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vy[i][XRES/CELL-2] = vy[i][XRES/CELL-3]*0.9f;
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vy[i][XRES/CELL-1] = vy[i][XRES/CELL-2]*0.9f;
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}
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for (i=0; i<XRES/CELL; i++) //reduces pressure/velocity on the edges every frame
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{
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pv[0][i] = pv[0][i]*0.8f;
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pv[1][i] = pv[1][i]*0.8f;
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pv[2][i] = pv[2][i]*0.8f;
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pv[YRES/CELL-2][i] = pv[YRES/CELL-2][i]*0.8f;
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pv[YRES/CELL-1][i] = pv[YRES/CELL-1][i]*0.8f;
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vx[0][i] = vx[1][i]*0.9f;
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vx[1][i] = vx[2][i]*0.9f;
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vx[YRES/CELL-2][i] = vx[YRES/CELL-3][i]*0.9f;
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vx[YRES/CELL-1][i] = vx[YRES/CELL-2][i]*0.9f;
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vy[0][i] = vy[1][i]*0.9f;
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vy[1][i] = vy[2][i]*0.9f;
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vy[YRES/CELL-2][i] = vy[YRES/CELL-3][i]*0.9f;
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vy[YRES/CELL-1][i] = vy[YRES/CELL-2][i]*0.9f;
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}
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for (j=1; j<YRES/CELL; j++) //clear some velocities near walls
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{
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for (i=1; i<XRES/CELL; i++)
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{
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if (bmap_blockair[j][i])
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{
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vx[j][i] = 0.0f;
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vx[j][i-1] = 0.0f;
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vy[j][i] = 0.0f;
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vy[j-1][i] = 0.0f;
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}
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}
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}
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for (y=1; y<YRES/CELL; y++) //pressure adjustments from velocity
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for (x=1; x<XRES/CELL; x++)
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{
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dp = 0.0f;
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dp += vx[y][x-1] - vx[y][x];
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dp += vy[y-1][x] - vy[y][x];
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pv[y][x] *= AIR_PLOSS;
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pv[y][x] += dp*AIR_TSTEPP;
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}
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for (y=0; y<YRES/CELL-1; y++) //velocity adjustments from pressure
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for (x=0; x<XRES/CELL-1; x++)
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{
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dx = dy = 0.0f;
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dx += pv[y][x] - pv[y][x+1];
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dy += pv[y][x] - pv[y+1][x];
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vx[y][x] *= AIR_VLOSS;
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vy[y][x] *= AIR_VLOSS;
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vx[y][x] += dx*AIR_TSTEPV;
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vy[y][x] += dy*AIR_TSTEPV;
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if (bmap_blockair[y][x] || bmap_blockair[y][x+1])
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vx[y][x] = 0;
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if (bmap_blockair[y][x] || bmap_blockair[y+1][x])
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vy[y][x] = 0;
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}
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for (y=0; y<YRES/CELL; y++) //update velocity and pressure
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for (x=0; x<XRES/CELL; x++)
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{
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dx = 0.0f;
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dy = 0.0f;
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dp = 0.0f;
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for (j=-1; j<2; j++)
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for (i=-1; i<2; i++)
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if (y+j>0 && y+j<YRES/CELL-1 &&
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x+i>0 && x+i<XRES/CELL-1 &&
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!bmap_blockair[y+j][x+i])
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{
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f = kernel[i+1+(j+1)*3];
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dx += vx[y+j][x+i]*f;
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dy += vy[y+j][x+i]*f;
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dp += pv[y+j][x+i]*f;
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}
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else
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{
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f = kernel[i+1+(j+1)*3];
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dx += vx[y][x]*f;
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dy += vy[y][x]*f;
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dp += pv[y][x]*f;
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}
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tx = x - dx*0.7f;
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ty = y - dy*0.7f;
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i = (int)tx;
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j = (int)ty;
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tx -= i;
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ty -= j;
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if (i>=2 && i<XRES/CELL-3 &&
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j>=2 && j<YRES/CELL-3)
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{
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dx *= 1.0f - AIR_VADV;
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dy *= 1.0f - AIR_VADV;
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dx += AIR_VADV*(1.0f-tx)*(1.0f-ty)*vx[j][i];
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dy += AIR_VADV*(1.0f-tx)*(1.0f-ty)*vy[j][i];
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dx += AIR_VADV*tx*(1.0f-ty)*vx[j][i+1];
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dy += AIR_VADV*tx*(1.0f-ty)*vy[j][i+1];
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dx += AIR_VADV*(1.0f-tx)*ty*vx[j+1][i];
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dy += AIR_VADV*(1.0f-tx)*ty*vy[j+1][i];
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dx += AIR_VADV*tx*ty*vx[j+1][i+1];
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dy += AIR_VADV*tx*ty*vy[j+1][i+1];
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}
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if (bmap[y][x] == WL_FAN)
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{
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dx += fvx[y][x];
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dy += fvy[y][x];
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}
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// pressure/velocity caps
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if (dp > 256.0f) dp = 256.0f;
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if (dp < -256.0f) dp = -256.0f;
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if (dx > 256.0f) dx = 256.0f;
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if (dx < -256.0f) dx = -256.0f;
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if (dy > 256.0f) dy = 256.0f;
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if (dy < -256.0f) dy = -256.0f;
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switch (airMode)
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{
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default:
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case 0: //Default
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break;
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case 1: //0 Pressure
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dp = 0.0f;
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break;
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case 2: //0 Velocity
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dx = 0.0f;
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dy = 0.0f;
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break;
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case 3: //0 Air
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dx = 0.0f;
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dy = 0.0f;
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dp = 0.0f;
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break;
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case 4: //No Update
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break;
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}
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ovx[y][x] = dx;
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ovy[y][x] = dy;
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opv[y][x] = dp;
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}
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memcpy(vx, ovx, sizeof(vx));
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memcpy(vy, ovy, sizeof(vy));
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memcpy(pv, opv, sizeof(pv));
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}
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}
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