/*****************************************************************************
* Wave Simulation in OpenGL
* (C) 2002 Jakob Thomsen
* http://home.in.tum.de/~thomsen
* Modified for GLFW by Sylvain Hellegouarch - sh@programmationworld.com
* Modified for variable frame rate by Marcus Geelnard
* 2003-Jan-31: Minor cleanups and speedups / MG
*****************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <GL/glfw3.h>
#ifndef M_PI
#define M_PI 3.1415926535897932384626433832795
#endif
/* Maximum delta T to allow for differential calculations */
#define MAX_DELTA_T 0.01
/* Animation speed (10.0 looks good) */
#define ANIMATION_SPEED 10.0
GLfloat alpha = 210.0f, beta = -70.0f;
GLfloat zoom = 2.0f;
int running = 1;
struct Vertex
{
GLfloat x,y,z;
GLfloat r,g,b;
};
#define GRIDW 50
#define GRIDH 50
#define VERTEXNUM (GRIDW*GRIDH)
#define QUADW (GRIDW-1)
#define QUADH (GRIDH-1)
#define QUADNUM (QUADW*QUADH)
GLuint quad[4*QUADNUM];
struct Vertex vertex[VERTEXNUM];
/* The grid will look like this:
*
* 3 4 5
* *---*---*
* | | |
* | 0 | 1 |
* | | |
* *---*---*
* 0 1 2
*/
void initVertices( void )
{
int x,y,p;
/* place the vertices in a grid */
for(y=0;y<GRIDH;y++)
for(x=0;x<GRIDW;x++)
{
p = y*GRIDW + x;
//vertex[p].x = (-GRIDW/2)+x+sin(2.0*M_PI*(double)y/(double)GRIDH);
//vertex[p].y = (-GRIDH/2)+y+cos(2.0*M_PI*(double)x/(double)GRIDW);
vertex[p].x = (GLfloat)(x-GRIDW/2)/(GLfloat)(GRIDW/2);
vertex[p].y = (GLfloat)(y-GRIDH/2)/(GLfloat)(GRIDH/2);
vertex[p].z = 0;//sin(d*M_PI);
//vertex[p].r = (GLfloat)x/(GLfloat)GRIDW;
//vertex[p].g = (GLfloat)y/(GLfloat)GRIDH;
//vertex[p].b = 1.0-((GLfloat)x/(GLfloat)GRIDW+(GLfloat)y/(GLfloat)GRIDH)/2.0;
if((x%4<2)^(y%4<2))
{
vertex[p].r = 0.0;
}
else
{
vertex[p].r=1.0;
}
vertex[p].g = (GLfloat)y/(GLfloat)GRIDH;
vertex[p].b = 1.f-((GLfloat)x/(GLfloat)GRIDW+(GLfloat)y/(GLfloat)GRIDH)/2.f;
}
for(y=0;y<QUADH;y++)
for(x=0;x<QUADW;x++)
{
p = 4*(y*QUADW + x);
/* first quad */
quad[p+0] = y *GRIDW+x; /* some point */
quad[p+1] = y *GRIDW+x+1; /* neighbor at the right side */
quad[p+2] = (y+1)*GRIDW+x+1; /* upper right neighbor */
quad[p+3] = (y+1)*GRIDW+x; /* upper neighbor */
}
}
double dt;
double p[GRIDW][GRIDH];
double vx[GRIDW][GRIDH], vy[GRIDW][GRIDH];
double ax[GRIDW][GRIDH], ay[GRIDW][GRIDH];
void initSurface( void )
{
int x, y;
double dx, dy, d;
for(y = 0; y<GRIDH; y++)
{
for(x = 0; x<GRIDW; x++)
{
dx = (double)(x-GRIDW/2);
dy = (double)(y-GRIDH/2);
d = sqrt( dx*dx + dy*dy );
if(d < 0.1 * (double)(GRIDW/2))
{
d = d * 10.0;
p[x][y] = -cos(d * (M_PI / (double)(GRIDW * 4))) * 100.0;
}
else
{
p[x][y] = 0.0;
}
vx[x][y] = 0.0;
vy[x][y] = 0.0;
}
}
}
/* Draw view */
void draw_screen( void )
{
/* Clear the color and depth buffers. */
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
/* We don't want to modify the projection matrix. */
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
/* Move back. */
glTranslatef(0.0, 0.0, -zoom);
/* Rotate the view */
glRotatef(beta, 1.0, 0.0, 0.0);
glRotatef(alpha, 0.0, 0.0, 1.0);
//glDrawArrays(GL_POINTS,0,VERTEXNUM); /* Points only */
glDrawElements(GL_QUADS, 4*QUADNUM, GL_UNSIGNED_INT, quad);
//glDrawElements(GL_LINES, QUADNUM, GL_UNSIGNED_INT, quad);
glfwSwapBuffers();
}
/* Initialize OpenGL */
void setup_opengl( void )
{
/* Our shading model--Gouraud (smooth). */
glShadeModel(GL_SMOOTH);
/* Culling. */
//glCullFace(GL_BACK);
//glFrontFace(GL_CCW);
//glEnable(GL_CULL_FACE);
/* Switch on the z-buffer. */
glEnable(GL_DEPTH_TEST);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
glVertexPointer(3/*3 components per vertex (x,y,z)*/, GL_FLOAT, sizeof(struct Vertex), vertex);
glColorPointer(3/*3 components per vertex (r,g,b)*/, GL_FLOAT, sizeof(struct Vertex), &vertex[0].r); //Pointer to the first color
glPointSize(2.0);
/* Background color is black. */
glClearColor(0, 0, 0, 0);
}
/* Modify the height of each vertex according to the pressure. */
void adjustGrid( void )
{
int pos;
int x, y;
for(y = 0; y<GRIDH; y++)
{
for(x = 0; x<GRIDW; x++)
{
pos = y*GRIDW + x;
vertex[pos].z = (float) (p[x][y]*(1.0/50.0));
}
}
}
/* Calculate wave propagation */
void calc( void )
{
int x, y, x2, y2;
double time_step = dt * ANIMATION_SPEED;
/* compute accelerations */
for(x = 0; x < GRIDW; x++)
{
x2 = (x + 1) % GRIDW;
for(y = 0; y < GRIDH; y++)
{
ax[x][y] = p[x][y] - p[x2][y];
}
}
for(y = 0; y < GRIDH;y++)
{
y2 = (y + 1) % GRIDH;
for(x = 0; x < GRIDW; x++)
{
ay[x][y] = p[x][y] - p[x][y2];
}
}
/* compute speeds */
for(x = 0; x < GRIDW; x++)
{
for(y = 0; y < GRIDH; y++)
{
vx[x][y] = vx[x][y] + ax[x][y] * time_step;
vy[x][y] = vy[x][y] + ay[x][y] * time_step;
}
}
/* compute pressure */
for(x = 1; x < GRIDW; x++)
{
x2 = x - 1;
for(y = 1; y < GRIDH; y++)
{
y2 = y - 1;
p[x][y] = p[x][y] + (vx[x2][y] - vx[x][y] + vy[x][y2] - vy[x][y]) * time_step;
}
}
}
/* Handle key strokes */
void handle_key_down(GLFWwindow window, int key, int action)
{
if( action != GLFW_PRESS )
{
return;
}
switch(key) {
case GLFW_KEY_ESC:
running = 0;
break;
case GLFW_KEY_SPACE:
initSurface();
break;
case GLFW_KEY_LEFT:
alpha+=5;
break;
case GLFW_KEY_RIGHT:
alpha-=5;
break;
case GLFW_KEY_UP:
beta-=5;
break;
case GLFW_KEY_DOWN:
beta+=5;
break;
case GLFW_KEY_PAGEUP:
if(zoom>1) zoom-=1;
break;
case GLFW_KEY_PAGEDOWN:
zoom+=1;
break;
default:
break;
}
}
/* Callback function for window resize events */
void handle_resize( GLFWwindow window, int width, int height )
{
float ratio = 1.0f;
if( height > 0 )
{
ratio = (float) width / (float) height;
}
/* Setup viewport (Place where the stuff will appear in the main window). */
glViewport(0, 0, width, height);
/*
* Change to the projection matrix and set
* our viewing volume.
*/
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluPerspective(60.0, ratio, 1.0, 1024.0);
}
/* Program entry point */
int main(int argc, char* argv[])
{
/* Dimensions of our window. */
int width, height;
/* Style of our window. */
int mode;
/* Frame time */
double t, t_old, dt_total;
GLFWwindow window;
/* Initialize GLFW */
if(glfwInit() == GL_FALSE)
{
fprintf(stderr, "GLFW initialization failed\n");
exit(-1);
}
/* Desired window properties */
width = 640;
height = 480;
mode = GLFW_WINDOWED;
glfwOpenWindowHint(GLFW_DEPTH_BITS, 16);
/* Open window */
window = glfwOpenWindow(width,height,mode);
if (!window)
{
fprintf(stderr, "Could not open window\n");
glfwTerminate();
exit(-1);
}
/* Set title */
glfwSetWindowTitle( window, "Wave Simulation" );
glfwSwapInterval( 1 );
/* Keyboard handler */
glfwSetKeyCallback( window, handle_key_down );
glfwEnable( window, GLFW_KEY_REPEAT );
/* Window resize handler */
glfwSetWindowSizeCallback( window, handle_resize );
/* Initialize OpenGL */
setup_opengl();
/* Initialize simulation */
initVertices();
initSurface();
adjustGrid();
/* Initialize timer */
t_old = glfwGetTime() - 0.01;
/* Main loop */
while(running)
{
/* Timing */
t = glfwGetTime();
dt_total = t - t_old;
t_old = t;
/* Safety - iterate if dt_total is too large */
while( dt_total > 0.0f )
{
/* Select iteration time step */
dt = dt_total > MAX_DELTA_T ? MAX_DELTA_T : dt_total;
dt_total -= dt;
/* Calculate wave propagation */
calc();
}
/* Compute height of each vertex */
adjustGrid();
/* Draw wave grid to OpenGL display */
draw_screen();
glfwPollEvents();
/* Still running? */
running = running && glfwIsWindow( window );
}
glfwTerminate();
return 0;
}