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glfw/examples/heightmap.c

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Added ignore rules for git, the heightmap examples from GLFW 2.7 and fixed a built issue on X11 introduced by using glxext.h
2010-09-24 16:47:25 -04:00
//========================================================================
// 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"
#define GLFW_NO_GLU 1
#include <GL/glfw3.h>
/* OpenGL 3.3 support
* Functions are effectively mapped in init_opengl() */
#ifndef GL_VERSION_3_0
/* no defines */
#endif
#ifndef GL_VERSION_2_0
typedef char GLchar;
#define GL_BLEND_EQUATION_RGB 0x8009
#define GL_VERTEX_ATTRIB_ARRAY_ENABLED 0x8622
#define GL_VERTEX_ATTRIB_ARRAY_SIZE 0x8623
#define GL_VERTEX_ATTRIB_ARRAY_STRIDE 0x8624
#define GL_VERTEX_ATTRIB_ARRAY_TYPE 0x8625
#define GL_CURRENT_VERTEX_ATTRIB 0x8626
#define GL_VERTEX_PROGRAM_POINT_SIZE 0x8642
#define GL_VERTEX_ATTRIB_ARRAY_POINTER 0x8645
#define GL_STENCIL_BACK_FUNC 0x8800
#define GL_STENCIL_BACK_FAIL 0x8801
#define GL_STENCIL_BACK_PASS_DEPTH_FAIL 0x8802
#define GL_STENCIL_BACK_PASS_DEPTH_PASS 0x8803
#define GL_MAX_DRAW_BUFFERS 0x8824
#define GL_DRAW_BUFFER0 0x8825
#define GL_DRAW_BUFFER1 0x8826
#define GL_DRAW_BUFFER2 0x8827
#define GL_DRAW_BUFFER3 0x8828
#define GL_DRAW_BUFFER4 0x8829
#define GL_DRAW_BUFFER5 0x882A
#define GL_DRAW_BUFFER6 0x882B
#define GL_DRAW_BUFFER7 0x882C
#define GL_DRAW_BUFFER8 0x882D
#define GL_DRAW_BUFFER9 0x882E
#define GL_DRAW_BUFFER10 0x882F
#define GL_DRAW_BUFFER11 0x8830
#define GL_DRAW_BUFFER12 0x8831
#define GL_DRAW_BUFFER13 0x8832
#define GL_DRAW_BUFFER14 0x8833
#define GL_DRAW_BUFFER15 0x8834
#define GL_BLEND_EQUATION_ALPHA 0x883D
#define GL_MAX_VERTEX_ATTRIBS 0x8869
#define GL_VERTEX_ATTRIB_ARRAY_NORMALIZED 0x886A
#define GL_MAX_TEXTURE_IMAGE_UNITS 0x8872
#define GL_FRAGMENT_SHADER 0x8B30
#define GL_VERTEX_SHADER 0x8B31
#define GL_MAX_FRAGMENT_UNIFORM_COMPONENTS 0x8B49
#define GL_MAX_VERTEX_UNIFORM_COMPONENTS 0x8B4A
#define GL_MAX_VARYING_FLOATS 0x8B4B
#define GL_MAX_VERTEX_TEXTURE_IMAGE_UNITS 0x8B4C
#define GL_MAX_COMBINED_TEXTURE_IMAGE_UNITS 0x8B4D
#define GL_SHADER_TYPE 0x8B4F
#define GL_FLOAT_VEC2 0x8B50
#define GL_FLOAT_VEC3 0x8B51
#define GL_FLOAT_VEC4 0x8B52
#define GL_INT_VEC2 0x8B53
#define GL_INT_VEC3 0x8B54
#define GL_INT_VEC4 0x8B55
#define GL_BOOL 0x8B56
#define GL_BOOL_VEC2 0x8B57
#define GL_BOOL_VEC3 0x8B58
#define GL_BOOL_VEC4 0x8B59
#define GL_FLOAT_MAT2 0x8B5A
#define GL_FLOAT_MAT3 0x8B5B
#define GL_FLOAT_MAT4 0x8B5C
#define GL_SAMPLER_1D 0x8B5D
#define GL_SAMPLER_2D 0x8B5E
#define GL_SAMPLER_3D 0x8B5F
#define GL_SAMPLER_CUBE 0x8B60
#define GL_SAMPLER_1D_SHADOW 0x8B61
#define GL_SAMPLER_2D_SHADOW 0x8B62
#define GL_DELETE_STATUS 0x8B80
#define GL_COMPILE_STATUS 0x8B81
#define GL_LINK_STATUS 0x8B82
#define GL_VALIDATE_STATUS 0x8B83
#define GL_INFO_LOG_LENGTH 0x8B84
#define GL_ATTACHED_SHADERS 0x8B85
#define GL_ACTIVE_UNIFORMS 0x8B86
#define GL_ACTIVE_UNIFORM_MAX_LENGTH 0x8B87
#define GL_SHADER_SOURCE_LENGTH 0x8B88
#define GL_ACTIVE_ATTRIBUTES 0x8B89
#define GL_ACTIVE_ATTRIBUTE_MAX_LENGTH 0x8B8A
#define GL_FRAGMENT_SHADER_DERIVATIVE_HINT 0x8B8B
#define GL_SHADING_LANGUAGE_VERSION 0x8B8C
#define GL_CURRENT_PROGRAM 0x8B8D
#define GL_POINT_SPRITE_COORD_ORIGIN 0x8CA0
#define GL_LOWER_LEFT 0x8CA1
#define GL_UPPER_LEFT 0x8CA2
#define GL_STENCIL_BACK_REF 0x8CA3
#define GL_STENCIL_BACK_VALUE_MASK 0x8CA4
#define GL_STENCIL_BACK_WRITEMASK 0x8CA5
#endif
#ifndef GL_VERSION_1_5
typedef ptrdiff_t GLintptr;
typedef ptrdiff_t GLsizeiptr;
#define GL_BUFFER_SIZE 0x8764
#define GL_BUFFER_USAGE 0x8765
#define GL_QUERY_COUNTER_BITS 0x8864
#define GL_CURRENT_QUERY 0x8865
#define GL_QUERY_RESULT 0x8866
#define GL_QUERY_RESULT_AVAILABLE 0x8867
#define GL_ARRAY_BUFFER 0x8892
#define GL_ELEMENT_ARRAY_BUFFER 0x8893
#define GL_ARRAY_BUFFER_BINDING 0x8894
#define GL_ELEMENT_ARRAY_BUFFER_BINDING 0x8895
#define GL_VERTEX_ATTRIB_ARRAY_BUFFER_BINDING 0x889F
#define GL_READ_ONLY 0x88B8
#define GL_WRITE_ONLY 0x88B9
#define GL_READ_WRITE 0x88BA
#define GL_BUFFER_ACCESS 0x88BB
#define GL_BUFFER_MAPPED 0x88BC
#define GL_BUFFER_MAP_POINTER 0x88BD
#define GL_STREAM_DRAW 0x88E0
#define GL_STREAM_READ 0x88E1
#define GL_STREAM_COPY 0x88E2
#define GL_STATIC_DRAW 0x88E4
#define GL_STATIC_READ 0x88E5
#define GL_STATIC_COPY 0x88E6
#define GL_DYNAMIC_DRAW 0x88E8
#define GL_DYNAMIC_READ 0x88E9
#define GL_DYNAMIC_COPY 0x88EA
#define GL_SAMPLES_PASSED 0x8914
#endif
/* OpenGL 3.0 */
typedef void (APIENTRY * PFN_glGenVertexArrays)(GLsizei n, GLuint *arrays);
typedef void (APIENTRY * PFN_glBindVertexArray)(GLuint array);
typedef void (APIENTRY * PFN_glDeleteVertexArrays)(GLsizei n, GLuint *arrays);
/* OpenGL 2.0 */
typedef GLuint (APIENTRY * PFN_glCreateShader)(GLenum type);
typedef void (APIENTRY * PFN_glDeleteShader)(GLuint shader);
typedef void (APIENTRY * PFN_glCompileShader)(GLuint shader);
typedef void (APIENTRY * PFN_glShaderSource)(GLuint shader, GLsizei count, const GLchar* *string, const GLint *length);
typedef void (APIENTRY * PFN_glGetShaderiv)(GLuint shader, GLenum pname, GLint *params);
typedef void (APIENTRY * PFN_glGetShaderInfoLog)(GLuint shader, GLsizei bufSize, GLsizei *length, GLchar *infoLog);
typedef GLuint (APIENTRY * PFN_glCreateProgram)(void);
typedef void (APIENTRY * PFN_glDeleteProgram)(GLuint program);
typedef void (APIENTRY * PFN_glAttachShader)(GLuint program, GLuint shader);
typedef void (APIENTRY * PFN_glLinkProgram)(GLuint program);
typedef void (APIENTRY * PFN_glGetProgramiv)(GLuint program, GLenum pname, GLint *params);
typedef void (APIENTRY * PFN_glGetProgramInfoLog)(GLuint shader, GLsizei bufSize, GLsizei *length, GLchar *infoLog);
typedef void (APIENTRY * PFN_glValidateProgram)(GLuint program);
typedef void (APIENTRY * PFN_glUseProgram)(GLuint program);
typedef GLint (APIENTRY * PFN_glGetUniformLocation)(GLuint program, const GLchar *name);
typedef void (APIENTRY * PFN_glUniformMatrix4fv)(GLint location, GLsizei count, GLboolean transpose, const GLfloat *value);
typedef GLint (APIENTRY * PFN_glGetAttribLocation)(GLuint program, const GLchar *name);
typedef void (APIENTRY * PFN_glEnableVertexAttribArray)(GLuint index);
typedef void (APIENTRY * PFN_glVertexAttrib1f)(GLuint index, GLfloat x);
typedef void (APIENTRY * PFN_glVertexAttribPointer)(GLuint index, GLint size, GLenum type, GLboolean normalized, GLsizei stride, const GLvoid *pointer);
/* OpenGL 1.5 */
typedef void (APIENTRY * PFN_glBindBuffer)(GLenum target, GLuint buffer);
typedef void (APIENTRY * PFN_glDeleteBuffers)(GLsizei n, const GLuint *buffers);
typedef void (APIENTRY * PFN_glGenBuffers)(GLsizei n, GLuint *buffers);
typedef void (APIENTRY * PFN_glBufferData)(GLenum target, GLsizeiptr size, const GLvoid *data, GLenum usage);
typedef void (APIENTRY * PFN_glBufferSubData)(GLenum target, GLintptr offset, GLsizeiptr size, const GLvoid *data);
/* OpenGL function pointers */
static PFN_glGenBuffers pglGenBuffers = NULL;
static PFN_glGenVertexArrays pglGenVertexArrays = NULL;
static PFN_glDeleteVertexArrays pglDeleteVertexArrays = NULL;
static PFN_glCreateShader pglCreateShader = NULL;
static PFN_glShaderSource pglShaderSource = NULL;
static PFN_glCompileShader pglCompileShader = NULL;
static PFN_glGetShaderiv pglGetShaderiv = NULL;
static PFN_glGetShaderInfoLog pglGetShaderInfoLog = NULL;
static PFN_glDeleteShader pglDeleteShader = NULL;
static PFN_glCreateProgram pglCreateProgram = NULL;
static PFN_glAttachShader pglAttachShader = NULL;
static PFN_glLinkProgram pglLinkProgram = NULL;
static PFN_glUseProgram pglUseProgram = NULL;
static PFN_glGetProgramiv pglGetProgramiv = NULL;
static PFN_glGetProgramInfoLog pglGetProgramInfoLog = NULL;
static PFN_glDeleteProgram pglDeleteProgram = NULL;
static PFN_glGetUniformLocation pglGetUniformLocation = NULL;
static PFN_glUniformMatrix4fv pglUniformMatrix4fv = NULL;
static PFN_glGetAttribLocation pglGetAttribLocation = 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 */
static PFN_glBindVertexArray pglBindVertexArray = NULL;
static PFN_glBufferData pglBufferData = NULL;
static PFN_glBindBuffer pglBindBuffer = NULL;
static PFN_glBufferSubData pglBufferSubData = NULL;
static PFN_glEnableVertexAttribArray pglEnableVertexAttribArray = NULL;
static PFN_glVertexAttribPointer pglVertexAttribPointer = NULL;
#define RESOLVE_GL_FCN(type, var, name) \
if (status == GL_TRUE) \
{\
var = glfwGetProcAddress((name));\
if ((var) == NULL)\
{\
status = GL_FALSE;\
}\
}
static GLboolean init_opengl(void)
{
GLboolean status = GL_TRUE;
RESOLVE_GL_FCN(PFN_glCreateShader, pglCreateShader, "glCreateShader");
RESOLVE_GL_FCN(PFN_glShaderSource, pglShaderSource, "glShaderSource");
RESOLVE_GL_FCN(PFN_glCompileShader, pglCompileShader, "glCompileShader");
RESOLVE_GL_FCN(PFN_glGetShaderiv, pglGetShaderiv, "glGetShaderiv");
RESOLVE_GL_FCN(PFN_glGetShaderInfoLog, pglGetShaderInfoLog, "glGetShaderInfoLog");
RESOLVE_GL_FCN(PFN_glDeleteShader, pglDeleteShader, "glDeleteShader");
RESOLVE_GL_FCN(PFN_glCreateProgram, pglCreateProgram, "glCreateProgram");
RESOLVE_GL_FCN(PFN_glAttachShader, pglAttachShader, "glAttachShader");
RESOLVE_GL_FCN(PFN_glLinkProgram, pglLinkProgram, "glLinkProgram");
RESOLVE_GL_FCN(PFN_glUseProgram, pglUseProgram, "glUseProgram");
RESOLVE_GL_FCN(PFN_glGetProgramiv, pglGetProgramiv, "glGetProgramiv");
RESOLVE_GL_FCN(PFN_glGetProgramInfoLog, pglGetProgramInfoLog, "glGetProgramInfoLog");
RESOLVE_GL_FCN(PFN_glDeleteProgram, pglDeleteProgram, "glDeleteProgram");
RESOLVE_GL_FCN(PFN_glGetUniformLocation, pglGetUniformLocation, "glGetUniformLocation");
RESOLVE_GL_FCN(PFN_glUniformMatrix4fv, pglUniformMatrix4fv, "glUniformMatrix4fv");
RESOLVE_GL_FCN(PFN_glGetAttribLocation, pglGetAttribLocation, "glGetAttribLocation");
RESOLVE_GL_FCN(PFN_glGenVertexArrays, pglGenVertexArrays, "glGenVertexArrays");
RESOLVE_GL_FCN(PFN_glDeleteVertexArrays, pglDeleteVertexArrays, "glDeleteVertexArrays");
RESOLVE_GL_FCN(PFN_glBindVertexArray, pglBindVertexArray, "glBindVertexArray");
RESOLVE_GL_FCN(PFN_glGenBuffers, pglGenBuffers, "glGenBuffers");
RESOLVE_GL_FCN(PFN_glBindBuffer, pglBindBuffer, "glBindBuffer");
RESOLVE_GL_FCN(PFN_glBufferData, pglBufferData, "glBufferData");
RESOLVE_GL_FCN(PFN_glBufferSubData, pglBufferSubData, "glBufferSubData");
RESOLVE_GL_FCN(PFN_glEnableVertexAttribArray, pglEnableVertexAttribArray, "glEnableVertexAttribArray");
RESOLVE_GL_FCN(PFN_glVertexAttribPointer, 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 + (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
*********************************************************************/
/* The program runs as long as this is GL_TRUE
*/
static GLboolean running = GL_TRUE;
/* GLFW Window management functions */
static int window_close_callback(GLFWwindow window)
{
running = GL_FALSE;
/* Disallow window closing
* The window will be closed when the main loop terminates */
return 0;
}
static void key_callback(GLFWwindow window, int key, int action)
{
switch(key)
{
case GLFW_KEY_ESC:
/* Exit program on Escape */
running = GL_FALSE;
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 (GL_TRUE != glfwInit())
{
fprintf(stderr, "ERROR: Unable to initialize GLFW\n");
usage();
free(vertex_shader_src);
free(fragment_shader_src);
exit(EXIT_FAILURE);
}
glfwOpenWindowHint(GLFW_WINDOW_NO_RESIZE, GL_TRUE);
glfwOpenWindowHint(GLFW_OPENGL_VERSION_MAJOR, 3);
glfwOpenWindowHint(GLFW_OPENGL_VERSION_MINOR, 2);
glfwOpenWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwOpenWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_FALSE);
window = glfwOpenWindow(800, 600, GLFW_WINDOWED, "GLFW OpenGL3 Heightmap demo");
if (! window )
{
fprintf(stderr, "ERROR: Unable to create the OpenGL context and associated window\n");
usage();
free(vertex_shader_src);
free(fragment_shader_src);
exit(EXIT_FAILURE);
}
glfwSetWindowCloseCallback(window, window_close_callback);
glfwSetKeyCallback(window, key_callback);
/* Register events callback */
if (GL_TRUE != init_opengl())
{
fprintf(stderr, "ERROR: unable to resolve OpenGL function pointers\n");
free(vertex_shader_src);
free(fragment_shader_src);
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();
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 (running)
{
++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();
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;
}
}
exit(EXIT_SUCCESS);
}
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