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A multi-platform library for OpenGL, OpenGL ES, Vulkan, window and input
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glfw/examples/heightmap.c

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//========================================================================
// Heightmap example program using OpenGL 3 core profile
// Copyright (c) 2010 Olivier Delannoy
//
// This software is provided 'as-is', without any express or implied
// warranty. In no event will the authors be held liable for any damages
// arising from the use of this software.
//
// Permission is granted to anyone to use this software for any purpose,
// including commercial applications, and to alter it and redistribute it
// freely, subject to the following restrictions:
//
// 1. The origin of this software must not be misrepresented; you must not
// claim that you wrote the original software. If you use this software
// in a product, an acknowledgment in the product documentation would
// be appreciated but is not required.
//
// 2. Altered source versions must be plainly marked as such, and must not
// be misrepresented as being the original software.
//
// 3. This notice may not be removed or altered from any source
// distribution.
//
//========================================================================
#include <stdlib.h>
#include <stdio.h>
#include <math.h>
#include <assert.h>
#include <stddef.h>
#include "getopt.h"
#include <GLFW/glfw3.h>
#include <GL/glext.h>
/* OpenGL function pointers */
static PFNGLGENBUFFERSPROC pglGenBuffers = NULL;
static PFNGLGENVERTEXARRAYSPROC pglGenVertexArrays = NULL;
static PFNGLDELETEVERTEXARRAYSPROC pglDeleteVertexArrays = NULL;
static PFNGLCREATESHADERPROC pglCreateShader = NULL;
static PFNGLSHADERSOURCEPROC pglShaderSource = NULL;
static PFNGLCOMPILESHADERPROC pglCompileShader = NULL;
static PFNGLGETSHADERIVPROC pglGetShaderiv = NULL;
static PFNGLGETSHADERINFOLOGPROC pglGetShaderInfoLog = NULL;
static PFNGLDELETESHADERPROC pglDeleteShader = NULL;
static PFNGLCREATEPROGRAMPROC pglCreateProgram = NULL;
static PFNGLATTACHSHADERPROC pglAttachShader = NULL;
static PFNGLLINKPROGRAMPROC pglLinkProgram = NULL;
static PFNGLUSEPROGRAMPROC pglUseProgram = NULL;
static PFNGLGETPROGRAMIVPROC pglGetProgramiv = NULL;
static PFNGLGETPROGRAMINFOLOGPROC pglGetProgramInfoLog = NULL;
static PFNGLDELETEPROGRAMPROC pglDeleteProgram = NULL;
static PFNGLGETUNIFORMLOCATIONPROC pglGetUniformLocation = NULL;
static PFNGLUNIFORMMATRIX4FVPROC pglUniformMatrix4fv = NULL;
static PFNGLGETATTRIBLOCATIONPROC pglGetAttribLocation = NULL;
static PFNGLBINDVERTEXARRAYPROC pglBindVertexArray = NULL;
static PFNGLBUFFERDATAPROC pglBufferData = NULL;
static PFNGLBINDBUFFERPROC pglBindBuffer = NULL;
static PFNGLBUFFERSUBDATAPROC pglBufferSubData = NULL;
static PFNGLENABLEVERTEXATTRIBARRAYPROC pglEnableVertexAttribArray = NULL;
static PFNGLVERTEXATTRIBPOINTERPROC pglVertexAttribPointer = NULL;
/* Map height updates */
#define MAX_CIRCLE_SIZE (5.0f)
#define MAX_DISPLACEMENT (1.0f)
#define DISPLACEMENT_SIGN_LIMIT (0.3f)
#define MAX_ITER (200)
#define NUM_ITER_AT_A_TIME (1)
/* Map general information */
#define MAP_SIZE (10.0f)
#define MAP_NUM_VERTICES (80)
#define MAP_NUM_TOTAL_VERTICES (MAP_NUM_VERTICES*MAP_NUM_VERTICES)
#define MAP_NUM_LINES (3* (MAP_NUM_VERTICES - 1) * (MAP_NUM_VERTICES - 1) + \
2 * (MAP_NUM_VERTICES - 1))
/* OpenGL function pointers */
#define RESOLVE_GL_FCN(type, var, name) \
if (status == GL_TRUE) \
{\
var = (type) glfwGetProcAddress((name));\
if ((var) == NULL)\
{\
status = GL_FALSE;\
}\
}
static GLboolean init_opengl(void)
{
GLboolean status = GL_TRUE;
RESOLVE_GL_FCN(PFNGLCREATESHADERPROC, pglCreateShader, "glCreateShader");
RESOLVE_GL_FCN(PFNGLSHADERSOURCEPROC, pglShaderSource, "glShaderSource");
RESOLVE_GL_FCN(PFNGLCOMPILESHADERPROC, pglCompileShader, "glCompileShader");
RESOLVE_GL_FCN(PFNGLGETSHADERIVPROC, pglGetShaderiv, "glGetShaderiv");
RESOLVE_GL_FCN(PFNGLGETSHADERINFOLOGPROC, pglGetShaderInfoLog, "glGetShaderInfoLog");
RESOLVE_GL_FCN(PFNGLDELETESHADERPROC, pglDeleteShader, "glDeleteShader");
RESOLVE_GL_FCN(PFNGLCREATEPROGRAMPROC, pglCreateProgram, "glCreateProgram");
RESOLVE_GL_FCN(PFNGLATTACHSHADERPROC, pglAttachShader, "glAttachShader");
RESOLVE_GL_FCN(PFNGLLINKPROGRAMPROC, pglLinkProgram, "glLinkProgram");
RESOLVE_GL_FCN(PFNGLUSEPROGRAMPROC, pglUseProgram, "glUseProgram");
RESOLVE_GL_FCN(PFNGLGETPROGRAMIVPROC, pglGetProgramiv, "glGetProgramiv");
RESOLVE_GL_FCN(PFNGLGETPROGRAMINFOLOGPROC, pglGetProgramInfoLog, "glGetProgramInfoLog");
RESOLVE_GL_FCN(PFNGLDELETEPROGRAMPROC, pglDeleteProgram, "glDeleteProgram");
RESOLVE_GL_FCN(PFNGLGETUNIFORMLOCATIONPROC, pglGetUniformLocation, "glGetUniformLocation");
RESOLVE_GL_FCN(PFNGLUNIFORMMATRIX4FVPROC, pglUniformMatrix4fv, "glUniformMatrix4fv");
RESOLVE_GL_FCN(PFNGLGETATTRIBLOCATIONPROC, pglGetAttribLocation, "glGetAttribLocation");
RESOLVE_GL_FCN(PFNGLGENVERTEXARRAYSPROC, pglGenVertexArrays, "glGenVertexArrays");
RESOLVE_GL_FCN(PFNGLDELETEVERTEXARRAYSPROC, pglDeleteVertexArrays, "glDeleteVertexArrays");
RESOLVE_GL_FCN(PFNGLBINDVERTEXARRAYPROC, pglBindVertexArray, "glBindVertexArray");
RESOLVE_GL_FCN(PFNGLGENBUFFERSPROC, pglGenBuffers, "glGenBuffers");
RESOLVE_GL_FCN(PFNGLBINDBUFFERPROC, pglBindBuffer, "glBindBuffer");
RESOLVE_GL_FCN(PFNGLBUFFERDATAPROC, pglBufferData, "glBufferData");
RESOLVE_GL_FCN(PFNGLBUFFERSUBDATAPROC, pglBufferSubData, "glBufferSubData");
RESOLVE_GL_FCN(PFNGLENABLEVERTEXATTRIBARRAYPROC, pglEnableVertexAttribArray, "glEnableVertexAttribArray");
RESOLVE_GL_FCN(PFNGLVERTEXATTRIBPOINTERPROC, pglVertexAttribPointer, "glVertexAttribPointer");
return status;
}
/**********************************************************************
* Default shader programs
*********************************************************************/
static const char* default_vertex_shader =
"#version 150\n"
"uniform mat4 project;\n"
"uniform mat4 modelview;\n"
"in float x;\n"
"in float y;\n"
"in float z;\n"
"\n"
"void main()\n"
"{\n"
" gl_Position = project * modelview * vec4(x, y, z, 1.0);\n"
"}\n";
static const char* default_fragment_shader =
"#version 150\n"
"out vec4 gl_FragColor;\n"
"void main()\n"
"{\n"
" gl_FragColor = vec4(0.2, 1.0, 0.2, 1.0); \n"
"}\n";
/**********************************************************************
* Values for shader uniforms
*********************************************************************/
/* Frustum configuration */
static GLfloat view_angle = 45.0f;
static GLfloat aspect_ratio = 4.0f/3.0f;
static GLfloat z_near = 1.0f;
static GLfloat z_far = 100.f;
/* Projection matrix */
static GLfloat projection_matrix[16] = {
1.0f, 0.0f, 0.0f, 0.0f,
0.0f, 1.0f, 0.0f, 0.0f,
0.0f, 0.0f, 1.0f, 0.0f,
0.0f, 0.0f, 0.0f, 1.0f
};
/* Model view matrix */
static GLfloat modelview_matrix[16] = {
1.0f, 0.0f, 0.0f, 0.0f,
0.0f, 1.0f, 0.0f, 0.0f,
0.0f, 0.0f, 1.0f, 0.0f,
0.0f, 0.0f, 0.0f, 1.0f
};
/**********************************************************************
* Heightmap vertex and index data
*********************************************************************/
static GLfloat map_vertices[3][MAP_NUM_TOTAL_VERTICES];
static GLuint map_line_indices[2*MAP_NUM_LINES];
/* Store uniform location for the shaders
* Those values are setup as part of the process of creating
* the shader program. They should not be used before creating
* the program.
*/
static GLuint mesh;
static GLuint mesh_vbo[4];
/**********************************************************************
* OpenGL helper functions
*********************************************************************/
/* Load a (text) file into memory and return its contents
*/
static char* read_file_content(const char* filename)
{
FILE* fd;
size_t size = 0;
char* result = NULL;
fd = fopen(filename, "r");
if (fd != NULL)
{
size = fseek(fd, 0, SEEK_END);
(void) fseek(fd, 0, SEEK_SET);
result = malloc(size + 1);
result[size] = '\0';
if (fread(result, size, 1, fd) != 1)
{
free(result);
result = NULL;
}
(void) fclose(fd);
}
return result;
}
/* Creates a shader object of the specified type using the specified text
*/
static GLuint make_shader(GLenum type, const char* shader_src)
{
GLuint shader;
GLint shader_ok;
GLsizei log_length;
char info_log[8192];
shader = pglCreateShader(type);
if (shader != 0)
{
pglShaderSource(shader, 1, (const GLchar**)&shader_src, NULL);
pglCompileShader(shader);
pglGetShaderiv(shader, GL_COMPILE_STATUS, &shader_ok);
if (shader_ok != GL_TRUE)
{
fprintf(stderr, "ERROR: Failed to compile %s shader\n", (type == GL_FRAGMENT_SHADER) ? "fragment" : "vertex" );
pglGetShaderInfoLog(shader, 8192, &log_length,info_log);
fprintf(stderr, "ERROR: \n%s\n\n", info_log);
pglDeleteShader(shader);
shader = 0;
}
}
return shader;
}
/* Creates a program object using the specified vertex and fragment text
*/
static GLuint make_shader_program(const char* vertex_shader_src, const char* fragment_shader_src)
{
GLuint program = 0u;
GLint program_ok;
GLuint vertex_shader = 0u;
GLuint fragment_shader = 0u;
GLsizei log_length;
char info_log[8192];
vertex_shader = make_shader(GL_VERTEX_SHADER, (vertex_shader_src == NULL) ? default_vertex_shader : vertex_shader_src);
if (vertex_shader != 0u)
{
fragment_shader = make_shader(GL_FRAGMENT_SHADER, (fragment_shader_src == NULL) ? default_fragment_shader : fragment_shader_src);
if (fragment_shader != 0u)
{
/* make the program that connect the two shader and link it */
program = pglCreateProgram();
if (program != 0u)
{
/* attach both shader and link */
pglAttachShader(program, vertex_shader);
pglAttachShader(program, fragment_shader);
pglLinkProgram(program);
pglGetProgramiv(program, GL_LINK_STATUS, &program_ok);
if (program_ok != GL_TRUE)
{
fprintf(stderr, "ERROR, failed to link shader program\n");
pglGetProgramInfoLog(program, 8192, &log_length, info_log);
fprintf(stderr, "ERROR: \n%s\n\n", info_log);
pglDeleteProgram(program);
pglDeleteShader(fragment_shader);
pglDeleteShader(vertex_shader);
program = 0u;
}
}
}
else
{
fprintf(stderr, "ERROR: Unable to load fragment shader\n");
pglDeleteShader(vertex_shader);
}
}
else
{
fprintf(stderr, "ERROR: Unable to load vertex shader\n");
}
return program;
}
/**********************************************************************
* Geometry creation functions
*********************************************************************/
/* Generate vertices and indices for the heightmap
*/
static void init_map(void)
{
int i;
int j;
int k;
GLfloat step = MAP_SIZE / (MAP_NUM_VERTICES - 1);
GLfloat x = 0.0f;
GLfloat z = 0.0f;
/* Create a flat grid */
k = 0;
for (i = 0 ; i < MAP_NUM_VERTICES ; ++i)
{
for (j = 0 ; j < MAP_NUM_VERTICES ; ++j)
{
map_vertices[0][k] = x;
map_vertices[1][k] = 0.0f;
map_vertices[2][k] = z;
z += step;
++k;
}
x += step;
z = 0.0f;
}
#if DEBUG_ENABLED
for (i = 0 ; i < MAP_NUM_TOTAL_VERTICES ; ++i)
{
printf ("Vertice %d (%f, %f, %f)\n",
i, map_vertices[0][i], map_vertices[1][i], map_vertices[2][i]);
}
#endif
/* create indices */
/* line fan based on i
* i+1
* | / i + n + 1
* | /
* |/
* i --- i + n
*/
/* close the top of the square */
k = 0;
for (i = 0 ; i < MAP_NUM_VERTICES -1 ; ++i)
{
map_line_indices[k++] = (i + 1) * MAP_NUM_VERTICES -1;
map_line_indices[k++] = (i + 2) * MAP_NUM_VERTICES -1;
}
/* close the right of the square */
for (i = 0 ; i < MAP_NUM_VERTICES -1 ; ++i)
{
map_line_indices[k++] = (MAP_NUM_VERTICES - 1) * MAP_NUM_VERTICES + i;
map_line_indices[k++] = (MAP_NUM_VERTICES - 1) * MAP_NUM_VERTICES + i + 1;
}
for (i = 0 ; i < (MAP_NUM_VERTICES - 1) ; ++i)
{
for (j = 0 ; j < (MAP_NUM_VERTICES - 1) ; ++j)
{
int ref = i * (MAP_NUM_VERTICES) + j;
map_line_indices[k++] = ref;
map_line_indices[k++] = ref + 1;
map_line_indices[k++] = ref;
map_line_indices[k++] = ref + MAP_NUM_VERTICES;
map_line_indices[k++] = ref;
map_line_indices[k++] = ref + MAP_NUM_VERTICES + 1;
}
}
#ifdef DEBUG_ENABLED
for (k = 0 ; k < 2 * MAP_NUM_LINES ; k += 2)
{
int beg, end;
beg = map_line_indices[k];
end = map_line_indices[k+1];
printf ("Line %d: %d -> %d (%f, %f, %f) -> (%f, %f, %f)\n",
k / 2, beg, end,
map_vertices[0][beg], map_vertices[1][beg], map_vertices[2][beg],
map_vertices[0][end], map_vertices[1][end], map_vertices[2][end]);
}
#endif
}
static void generate_heightmap__circle(float* center_x, float* center_y,
float* size, float* displacement)
{
float sign;
/* random value for element in between [0-1.0] */
*center_x = (MAP_SIZE * rand()) / (1.0f * RAND_MAX);
*center_y = (MAP_SIZE * rand()) / (1.0f * RAND_MAX);
*size = (MAX_CIRCLE_SIZE * rand()) / (1.0f * RAND_MAX);
sign = (1.0f * rand()) / (1.0f * RAND_MAX);
sign = (sign < DISPLACEMENT_SIGN_LIMIT) ? -1.0f : 1.0f;
*displacement = (sign * (MAX_DISPLACEMENT * rand())) / (1.0f * RAND_MAX);
}
/* Run the specified number of iterations of the generation process for the
* heightmap
*/
static void update_map(int num_iter)
{
assert(num_iter > 0);
while(num_iter)
{
/* center of the circle */
float center_x;
float center_z;
float circle_size;
float disp;
size_t ii;
generate_heightmap__circle(&center_x, &center_z, &circle_size, &disp);
disp = disp / 2.0f;
for (ii = 0u ; ii < MAP_NUM_TOTAL_VERTICES ; ++ii)
{
GLfloat dx = center_x - map_vertices[0][ii];
GLfloat dz = center_z - map_vertices[2][ii];
GLfloat pd = (2.0f * sqrtf((dx * dx) + (dz * dz))) / circle_size;
if (fabs(pd) <= 1.0f)
{
/* tx,tz is within the circle */
GLfloat new_height = disp + (float) (cos(pd*3.14f)*disp);
map_vertices[1][ii] += new_height;
}
}
--num_iter;
}
}
/**********************************************************************
* OpenGL helper functions
*********************************************************************/
/* Create VBO, IBO and VAO objects for the heightmap geometry and bind them to
* the specified program object
*/
static void make_mesh(GLuint program)
{
GLuint attrloc;
pglGenVertexArrays(1, &mesh);
pglGenBuffers(4, mesh_vbo);
pglBindVertexArray(mesh);
/* Prepare the data for drawing through a buffer inidices */
pglBindBuffer(GL_ELEMENT_ARRAY_BUFFER, mesh_vbo[3]);
pglBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(GLuint)* MAP_NUM_LINES * 2, map_line_indices, GL_STATIC_DRAW);
/* Prepare the attributes for rendering */
attrloc = pglGetAttribLocation(program, "x");
pglBindBuffer(GL_ARRAY_BUFFER, mesh_vbo[0]);
pglBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat) * MAP_NUM_TOTAL_VERTICES, &map_vertices[0][0], GL_STATIC_DRAW);
pglEnableVertexAttribArray(attrloc);
pglVertexAttribPointer(attrloc, 1, GL_FLOAT, GL_FALSE, 0, 0);
attrloc = pglGetAttribLocation(program, "z");
pglBindBuffer(GL_ARRAY_BUFFER, mesh_vbo[2]);
pglBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat) * MAP_NUM_TOTAL_VERTICES, &map_vertices[2][0], GL_STATIC_DRAW);
pglEnableVertexAttribArray(attrloc);
pglVertexAttribPointer(attrloc, 1, GL_FLOAT, GL_FALSE, 0, 0);
attrloc = pglGetAttribLocation(program, "y");
pglBindBuffer(GL_ARRAY_BUFFER, mesh_vbo[1]);
pglBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat) * MAP_NUM_TOTAL_VERTICES, &map_vertices[1][0], GL_DYNAMIC_DRAW);
pglEnableVertexAttribArray(attrloc);
pglVertexAttribPointer(attrloc, 1, GL_FLOAT, GL_FALSE, 0, 0);
}
/* Update VBO vertices from source data
*/
static void update_mesh(void)
{
pglBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(GLfloat) * MAP_NUM_TOTAL_VERTICES, &map_vertices[1][0]);
}
/**********************************************************************
* GLFW callback functions
*********************************************************************/
static void key_callback(GLFWwindow* window, int key, int scancode, int action, int mods)
{
switch(key)
{
case GLFW_KEY_ESCAPE:
/* Exit program on Escape */
glfwSetWindowShouldClose(window, GL_TRUE);
break;
}
}
/* Print usage information */
static void usage(void)
{
printf("Usage: heightmap [-v <vertex_shader_path>] [-f <fragment_shader_path>]\n");
printf(" heightmap [-h]\n");
}
int main(int argc, char** argv)
{
GLFWwindow* window;
int ch, iter;
double dt;
double last_update_time;
int frame;
float f;
GLint uloc_modelview;
GLint uloc_project;
char* vertex_shader_path = NULL;
char* fragment_shader_path = NULL;
char* vertex_shader_src = NULL;
char* fragment_shader_src = NULL;
GLuint shader_program;
while ((ch = getopt(argc, argv, "f:v:h")) != -1)
{
switch (ch)
{
case 'f':
fragment_shader_path = optarg;
break;
case 'v':
vertex_shader_path = optarg;
break;
case 'h':
usage();
exit(EXIT_SUCCESS);
default:
usage();
exit(EXIT_FAILURE);
}
}
if (fragment_shader_path)
{
vertex_shader_src = read_file_content(fragment_shader_path);
if (!fragment_shader_src)
{
fprintf(stderr,
"ERROR: unable to load fragment shader from '%s'\n",
fragment_shader_path);
exit(EXIT_FAILURE);
}
}
if (vertex_shader_path)
{
vertex_shader_src = read_file_content(vertex_shader_path);
if (!vertex_shader_src)
{
fprintf(stderr,
"ERROR: unable to load vertex shader from '%s'\n",
fragment_shader_path);
exit(EXIT_FAILURE);
}
}
if (!glfwInit())
{
fprintf(stderr, "ERROR: Unable to initialize GLFW\n");
usage();
free(vertex_shader_src);
free(fragment_shader_src);
exit(EXIT_FAILURE);
}
glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_FALSE);
window = glfwCreateWindow(800, 600, "GLFW OpenGL3 Heightmap demo", NULL, NULL);
if (! window )
{
fprintf(stderr, "ERROR: Unable to create the OpenGL context and associated window\n");
usage();
free(vertex_shader_src);
free(fragment_shader_src);
glfwTerminate();
exit(EXIT_FAILURE);
}
/* Register events callback */
glfwSetKeyCallback(window, key_callback);
glfwMakeContextCurrent(window);
if (GL_TRUE != init_opengl())
{
fprintf(stderr, "ERROR: unable to resolve OpenGL function pointers\n");
free(vertex_shader_src);
free(fragment_shader_src);
glfwTerminate();
exit(EXIT_FAILURE);
}
/* Prepare opengl resources for rendering */
shader_program = make_shader_program(vertex_shader_src , fragment_shader_src);
free(vertex_shader_src);
free(fragment_shader_src);
if (shader_program == 0u)
{
fprintf(stderr, "ERROR: during creation of the shader program\n");
usage();
glfwTerminate();
exit(EXIT_FAILURE);
}
pglUseProgram(shader_program);
uloc_project = pglGetUniformLocation(shader_program, "project");
uloc_modelview = pglGetUniformLocation(shader_program, "modelview");
/* Compute the projection matrix */
f = 1.0f / tanf(view_angle / 2.0f);
projection_matrix[0] = f / aspect_ratio;
projection_matrix[5] = f;
projection_matrix[10] = (z_far + z_near)/ (z_near - z_far);
projection_matrix[11] = -1.0f;
projection_matrix[14] = 2.0f * (z_far * z_near) / (z_near - z_far);
pglUniformMatrix4fv(uloc_project, 1, GL_FALSE, projection_matrix);
/* Set the camera position */
modelview_matrix[12] = -5.0f;
modelview_matrix[13] = -5.0f;
modelview_matrix[14] = -20.0f;
pglUniformMatrix4fv(uloc_modelview, 1, GL_FALSE, modelview_matrix);
/* Create mesh data */
init_map();
make_mesh(shader_program);
/* Create vao + vbo to store the mesh */
/* Create the vbo to store all the information for the grid and the height */
/* setup the scene ready for rendering */
glViewport(0, 0, 800, 600);
glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
/* main loop */
frame = 0;
iter = 0;
dt = last_update_time = glfwGetTime();
while (!glfwWindowShouldClose(window))
{
++frame;
/* render the next frame */
glClear(GL_COLOR_BUFFER_BIT);
glDrawElements(GL_LINES, 2* MAP_NUM_LINES , GL_UNSIGNED_INT, 0);
/* display and process events through callbacks */
glfwSwapBuffers(window);
glfwPollEvents();
/* Check the frame rate and update the heightmap if needed */
dt = glfwGetTime();
if ((dt - last_update_time) > 0.2)
{
/* generate the next iteration of the heightmap */
if (iter < MAX_ITER)
{
update_map(NUM_ITER_AT_A_TIME);
update_mesh();
iter += NUM_ITER_AT_A_TIME;
}
last_update_time = dt;
frame = 0;
}
}
glfwTerminate();
exit(EXIT_SUCCESS);
}