blob: f5af37914ed7ef73ea270b47046a8b784a993627 [file] [log] [blame] 
 /***************************************************************************** * 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 * 2010-10-24: Formatting and cleanup - Camilla Löwy *****************************************************************************/ #if defined(_MSC_VER) // Make MS math.h define M_PI #define _USE_MATH_DEFINES #endif #include #include #include #include #include #include // 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.f, beta = -70.f; GLfloat zoom = 2.f; double cursorX; double cursorY; 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 */ //======================================================================== // Initialize grid geometry //======================================================================== void init_vertices(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 = (GLfloat) (x - GRIDW / 2) / (GLfloat) (GRIDW / 2); vertex[p].y = (GLfloat) (y - GRIDH / 2) / (GLfloat) (GRIDH / 2); vertex[p].z = 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); 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]; //======================================================================== // Initialize grid //======================================================================== void init_grid(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 scene //======================================================================== void draw_scene(GLFWwindow* window) { // 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); glDrawElements(GL_QUADS, 4 * QUADNUM, GL_UNSIGNED_INT, quad); glfwSwapBuffers(window); } //======================================================================== // Initialize Miscellaneous OpenGL state //======================================================================== void init_opengl(void) { // Use Gouraud (smooth) shading glShadeModel(GL_SMOOTH); // Switch on the z-buffer glEnable(GL_DEPTH_TEST); glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_COLOR_ARRAY); glVertexPointer(3, GL_FLOAT, sizeof(struct Vertex), vertex); glColorPointer(3, 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 adjust_grid(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_grid(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; } } } //======================================================================== // Print errors //======================================================================== static void error_callback(int error, const char* description) { fprintf(stderr, "Error: %s\n", description); } //======================================================================== // Handle key strokes //======================================================================== void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods) { if (action != GLFW_PRESS) return; switch (key) { case GLFW_KEY_ESCAPE: glfwSetWindowShouldClose(window, GLFW_TRUE); break; case GLFW_KEY_SPACE: init_grid(); 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_PAGE_UP: zoom -= 0.25f; if (zoom < 0.f) zoom = 0.f; break; case GLFW_KEY_PAGE_DOWN: zoom += 0.25f; break; default: break; } } //======================================================================== // Callback function for mouse button events //======================================================================== void mouse_button_callback(GLFWwindow* window, int button, int action, int mods) { if (button != GLFW_MOUSE_BUTTON_LEFT) return; if (action == GLFW_PRESS) { glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_DISABLED); glfwGetCursorPos(window, &cursorX, &cursorY); } else glfwSetInputMode(window, GLFW_CURSOR, GLFW_CURSOR_NORMAL); } //======================================================================== // Callback function for cursor motion events //======================================================================== void cursor_position_callback(GLFWwindow* window, double x, double y) { if (glfwGetInputMode(window, GLFW_CURSOR) == GLFW_CURSOR_DISABLED) { alpha += (GLfloat) (x - cursorX) / 10.f; beta += (GLfloat) (y - cursorY) / 10.f; cursorX = x; cursorY = y; } } //======================================================================== // Callback function for scroll events //======================================================================== void scroll_callback(GLFWwindow* window, double x, double y) { zoom += (float) y / 4.f; if (zoom < 0) zoom = 0; } //======================================================================== // Callback function for framebuffer resize events //======================================================================== void framebuffer_size_callback(GLFWwindow* window, int width, int height) { float ratio = 1.f; mat4x4 projection; if (height > 0) ratio = (float) width / (float) height; // Setup viewport glViewport(0, 0, width, height); // Change to the projection matrix and set our viewing volume glMatrixMode(GL_PROJECTION); mat4x4_perspective(projection, 60.f * (float) M_PI / 180.f, ratio, 1.f, 1024.f); glLoadMatrixf((const GLfloat*) projection); } //======================================================================== // main //======================================================================== int main(int argc, char* argv[]) { GLFWwindow* window; double t, dt_total, t_old; int width, height; glfwSetErrorCallback(error_callback); if (!glfwInit()) exit(EXIT_FAILURE); window = glfwCreateWindow(640, 480, "Wave Simulation", NULL, NULL); if (!window) { glfwTerminate(); exit(EXIT_FAILURE); } glfwSetKeyCallback(window, key_callback); glfwSetFramebufferSizeCallback(window, framebuffer_size_callback); glfwSetMouseButtonCallback(window, mouse_button_callback); glfwSetCursorPosCallback(window, cursor_position_callback); glfwSetScrollCallback(window, scroll_callback); glfwMakeContextCurrent(window); gladLoadGLLoader((GLADloadproc) glfwGetProcAddress); glfwSwapInterval(1); glfwGetFramebufferSize(window, &width, &height); framebuffer_size_callback(window, width, height); // Initialize OpenGL init_opengl(); // Initialize simulation init_vertices(); init_grid(); adjust_grid(); // Initialize timer t_old = glfwGetTime() - 0.01; while (!glfwWindowShouldClose(window)) { t = glfwGetTime(); dt_total = t - t_old; t_old = t; // Safety - iterate if dt_total is too large while (dt_total > 0.f) { // Select iteration time step dt = dt_total > MAX_DELTA_T ? MAX_DELTA_T : dt_total; dt_total -= dt; // Calculate wave propagation calc_grid(); } // Compute height of each vertex adjust_grid(); // Draw wave grid to OpenGL display draw_scene(window); glfwPollEvents(); } exit(EXIT_SUCCESS); }