453 lines
11 KiB
C
453 lines
11 KiB
C
/*****************************************************************************
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* Wave Simulation in OpenGL
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* (C) 2002 Jakob Thomsen
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* http://home.in.tum.de/~thomsen
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* Modified for GLFW by Sylvain Hellegouarch - sh@programmationworld.com
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* Modified for variable frame rate by Marcus Geelnard
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* 2003-Jan-31: Minor cleanups and speedups / MG
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* 2010-10-24: Formatting and cleanup - Camilla Berglund
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*****************************************************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#define GLFW_INCLUDE_GLU
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#include <GLFW/glfw3.h>
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#ifndef M_PI
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#define M_PI 3.1415926535897932384626433832795
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#endif
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// Maximum delta T to allow for differential calculations
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#define MAX_DELTA_T 0.01
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// Animation speed (10.0 looks good)
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#define ANIMATION_SPEED 10.0
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GLfloat alpha = 210.f, beta = -70.f;
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GLfloat zoom = 2.f;
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double cursorX;
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double cursorY;
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struct Vertex
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{
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GLfloat x, y, z;
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GLfloat r, g, b;
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};
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#define GRIDW 50
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#define GRIDH 50
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#define VERTEXNUM (GRIDW*GRIDH)
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#define QUADW (GRIDW - 1)
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#define QUADH (GRIDH - 1)
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#define QUADNUM (QUADW*QUADH)
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GLuint quad[4 * QUADNUM];
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struct Vertex vertex[VERTEXNUM];
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/* The grid will look like this:
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*
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* 3 4 5
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* *---*---*
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* | | |
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* | 0 | 1 |
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* | | |
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* *---*---*
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* 0 1 2
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*/
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//========================================================================
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// Initialize grid geometry
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//========================================================================
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void init_vertices(void)
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{
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int x, y, p;
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// Place the vertices in a grid
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for (y = 0; y < GRIDH; y++)
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{
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for (x = 0; x < GRIDW; x++)
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{
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p = y * GRIDW + x;
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vertex[p].x = (GLfloat) (x - GRIDW / 2) / (GLfloat) (GRIDW / 2);
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vertex[p].y = (GLfloat) (y - GRIDH / 2) / (GLfloat) (GRIDH / 2);
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vertex[p].z = 0;
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if ((x % 4 < 2) ^ (y % 4 < 2))
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vertex[p].r = 0.0;
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else
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vertex[p].r = 1.0;
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vertex[p].g = (GLfloat) y / (GLfloat) GRIDH;
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vertex[p].b = 1.f - ((GLfloat) x / (GLfloat) GRIDW + (GLfloat) y / (GLfloat) GRIDH) / 2.f;
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}
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}
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for (y = 0; y < QUADH; y++)
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{
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for (x = 0; x < QUADW; x++)
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{
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p = 4 * (y * QUADW + x);
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quad[p + 0] = y * GRIDW + x; // Some point
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quad[p + 1] = y * GRIDW + x + 1; // Neighbor at the right side
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quad[p + 2] = (y + 1) * GRIDW + x + 1; // Upper right neighbor
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quad[p + 3] = (y + 1) * GRIDW + x; // Upper neighbor
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}
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}
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}
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double dt;
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double p[GRIDW][GRIDH];
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double vx[GRIDW][GRIDH], vy[GRIDW][GRIDH];
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double ax[GRIDW][GRIDH], ay[GRIDW][GRIDH];
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//========================================================================
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// Initialize grid
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//========================================================================
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void init_grid(void)
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{
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int x, y;
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double dx, dy, d;
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for (y = 0; y < GRIDH; y++)
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{
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for (x = 0; x < GRIDW; x++)
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{
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dx = (double) (x - GRIDW / 2);
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dy = (double) (y - GRIDH / 2);
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d = sqrt(dx * dx + dy * dy);
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if (d < 0.1 * (double) (GRIDW / 2))
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{
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d = d * 10.0;
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p[x][y] = -cos(d * (M_PI / (double)(GRIDW * 4))) * 100.0;
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}
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else
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p[x][y] = 0.0;
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vx[x][y] = 0.0;
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vy[x][y] = 0.0;
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}
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}
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}
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//========================================================================
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// Draw scene
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//========================================================================
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void draw_scene(GLFWwindow* window)
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{
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// Clear the color and depth buffers
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glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
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// We don't want to modify the projection matrix
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glMatrixMode(GL_MODELVIEW);
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glLoadIdentity();
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// Move back
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glTranslatef(0.0, 0.0, -zoom);
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// Rotate the view
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glRotatef(beta, 1.0, 0.0, 0.0);
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glRotatef(alpha, 0.0, 0.0, 1.0);
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glDrawElements(GL_QUADS, 4 * QUADNUM, GL_UNSIGNED_INT, quad);
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glfwSwapBuffers(window);
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}
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//========================================================================
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// Initialize Miscellaneous OpenGL state
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//========================================================================
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void init_opengl(void)
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{
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// Use Gouraud (smooth) shading
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glShadeModel(GL_SMOOTH);
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// Switch on the z-buffer
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glEnable(GL_DEPTH_TEST);
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glEnableClientState(GL_VERTEX_ARRAY);
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glEnableClientState(GL_COLOR_ARRAY);
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glVertexPointer(3, GL_FLOAT, sizeof(struct Vertex), vertex);
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glColorPointer(3, GL_FLOAT, sizeof(struct Vertex), &vertex[0].r); // Pointer to the first color
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glPointSize(2.0);
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// Background color is black
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glClearColor(0, 0, 0, 0);
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}
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//========================================================================
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// Modify the height of each vertex according to the pressure
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//========================================================================
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void adjust_grid(void)
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{
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int pos;
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int x, y;
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for (y = 0; y < GRIDH; y++)
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{
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for (x = 0; x < GRIDW; x++)
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{
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pos = y * GRIDW + x;
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vertex[pos].z = (float) (p[x][y] * (1.0 / 50.0));
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}
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}
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}
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//========================================================================
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// Calculate wave propagation
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//========================================================================
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void calc_grid(void)
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{
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int x, y, x2, y2;
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double time_step = dt * ANIMATION_SPEED;
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// Compute accelerations
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for (x = 0; x < GRIDW; x++)
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{
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x2 = (x + 1) % GRIDW;
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for(y = 0; y < GRIDH; y++)
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ax[x][y] = p[x][y] - p[x2][y];
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}
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for (y = 0; y < GRIDH; y++)
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{
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y2 = (y + 1) % GRIDH;
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for(x = 0; x < GRIDW; x++)
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ay[x][y] = p[x][y] - p[x][y2];
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}
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// Compute speeds
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for (x = 0; x < GRIDW; x++)
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{
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for (y = 0; y < GRIDH; y++)
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{
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vx[x][y] = vx[x][y] + ax[x][y] * time_step;
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vy[x][y] = vy[x][y] + ay[x][y] * time_step;
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}
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}
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// Compute pressure
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for (x = 1; x < GRIDW; x++)
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{
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x2 = x - 1;
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for (y = 1; y < GRIDH; y++)
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{
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y2 = y - 1;
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p[x][y] = p[x][y] + (vx[x2][y] - vx[x][y] + vy[x][y2] - vy[x][y]) * time_step;
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}
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}
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}
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//========================================================================
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// Print errors
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//========================================================================
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static void error_callback(int error, const char* description)
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{
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fprintf(stderr, "Error: %s\n", description);
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}
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//========================================================================
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// Handle key strokes
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//========================================================================
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void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
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{
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if (action != GLFW_PRESS)
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return;
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switch (key)
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{
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case GLFW_KEY_ESCAPE:
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glfwSetWindowShouldClose(window, GL_TRUE);
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break;
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case GLFW_KEY_SPACE:
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init_grid();
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break;
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case GLFW_KEY_LEFT:
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alpha += 5;
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break;
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case GLFW_KEY_RIGHT:
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alpha -= 5;
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break;
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case GLFW_KEY_UP:
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beta -= 5;
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break;
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case GLFW_KEY_DOWN:
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beta += 5;
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break;
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case GLFW_KEY_PAGE_UP:
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zoom -= 0.25f;
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if (zoom < 0.f)
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zoom = 0.f;
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break;
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case GLFW_KEY_PAGE_DOWN:
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zoom += 0.25f;
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break;
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default:
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break;
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}
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}
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//========================================================================
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// Callback function for mouse button events
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//========================================================================
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void mouse_button_callback(GLFWwindow* window, int button, int action, int mods)
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{
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if (button != GLFW_MOUSE_BUTTON_LEFT)
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return;
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if (action == GLFW_PRESS)
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{
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glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED);
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glfwGetCursorPos(window, &cursorX, &cursorY);
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}
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else
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glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_NORMAL);
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}
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//========================================================================
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// Callback function for cursor motion events
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//========================================================================
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void cursor_position_callback(GLFWwindow* window, double x, double y)
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{
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if (glfwGetInputMode(window, GLFW_CURSOR) == GLFW_CURSOR_DISABLED)
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{
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alpha += (GLfloat) (x - cursorX) / 10.f;
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beta += (GLfloat) (y - cursorY) / 10.f;
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cursorX = x;
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cursorY = y;
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}
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}
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//========================================================================
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// Callback function for scroll events
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//========================================================================
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void scroll_callback(GLFWwindow* window, double x, double y)
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{
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zoom += (float) y / 4.f;
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if (zoom < 0)
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zoom = 0;
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}
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//========================================================================
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// Callback function for framebuffer resize events
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//========================================================================
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void framebuffer_size_callback(GLFWwindow* window, int width, int height)
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{
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float ratio = 1.f;
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if (height > 0)
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ratio = (float) width / (float) height;
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// Setup viewport
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glViewport(0, 0, width, height);
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// Change to the projection matrix and set our viewing volume
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glMatrixMode(GL_PROJECTION);
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glLoadIdentity();
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gluPerspective(60.0, ratio, 1.0, 1024.0);
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}
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//========================================================================
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// main
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//========================================================================
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int main(int argc, char* argv[])
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{
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GLFWwindow* window;
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double t, dt_total, t_old;
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int width, height;
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glfwSetErrorCallback(error_callback);
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if (!glfwInit())
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exit(EXIT_FAILURE);
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window = glfwCreateWindow(640, 480, "Wave Simulation", NULL, NULL);
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if (!window)
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{
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glfwTerminate();
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exit(EXIT_FAILURE);
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}
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glfwSetKeyCallback(window, key_callback);
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glfwSetFramebufferSizeCallback(window, framebuffer_size_callback);
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glfwSetMouseButtonCallback(window, mouse_button_callback);
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glfwSetCursorPosCallback(window, cursor_position_callback);
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glfwSetScrollCallback(window, scroll_callback);
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glfwMakeContextCurrent(window);
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glfwSwapInterval(1);
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glfwGetFramebufferSize(window, &width, &height);
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framebuffer_size_callback(window, width, height);
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// Initialize OpenGL
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init_opengl();
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// Initialize simulation
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init_vertices();
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init_grid();
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adjust_grid();
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// Initialize timer
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t_old = glfwGetTime() - 0.01;
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while (!glfwWindowShouldClose(window))
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{
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t = glfwGetTime();
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dt_total = t - t_old;
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t_old = t;
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// Safety - iterate if dt_total is too large
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while (dt_total > 0.f)
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{
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// Select iteration time step
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dt = dt_total > MAX_DELTA_T ? MAX_DELTA_T : dt_total;
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dt_total -= dt;
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// Calculate wave propagation
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calc_grid();
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}
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// Compute height of each vertex
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adjust_grid();
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// Draw wave grid to OpenGL display
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draw_scene(window);
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glfwPollEvents();
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}
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exit(EXIT_SUCCESS);
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}
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