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glfw/examples/wave.c
Camilla Löwy d7e30b1c74 Replace glad and the Vulkan SDK with glad2
This removes all dependencies from the GLFW test programs on the Vulkan
SDK.

It also removes support for linking the GLFW shared library (dynamic
library, DLL) against the Vulkan loader static library.
2019-04-15 02:45:48 +02:00

462 lines
12 KiB
C

/*****************************************************************************
* 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 <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <glad/gl.h>
#include <GLFW/glfw3.h>
#include <linmath.h>
// 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);
gladLoadGL(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();
}
glfwTerminate();
exit(EXIT_SUCCESS);
}