I've successfully got some triangles to show up on screen together with some textures and a couple of event listeners. However, my texture is not rendering properly, it seems like pixels between 0 and 255 in brightness gets disorted while completely black/white pixels are rendering as they should. <- This might not be the best description but I will provide an example below.
This is the texture I'm trying to map onto my two triangles at the moment:
Here is the result after compiling and running the program:
What I think is that it may have something to do with the shaders, at the moment I do not have any shaders activated, neither vertex nor fragment shaders. I don't know if this is the problem but it might be a clue to it all.
Below is my main.cpp:
#include <iostream>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/keysymdef.h>
#include <GL/glx.h>
#include <GL/gl.h>
// #include <GL/glut.h>
// #include <GL/glu.h>
#include <sys/time.h>
#include <unistd.h>
#define GLX_CONTEXT_MAJOR_VERSION_ARB 0x2091
#define GLX_CONTEXT_MINOR_VERSION_ARB 0x2092
typedef GLXContext (*GLXCREATECONTEXTATTRIBSARBPROC)(Display*, GLXFBConfig, GLXContext, Bool, const int*);
#define WINDOW_WIDTH 800
#define WINDOW_HEIGHT 800
#define FPS 30
uint8_t shutdown = 0;
#define SKIP_TICKS ( 1000 / FPS )
// macros
void Render( void );
void HandleEvents( XEvent ev );
void Resize( int w, int h );
void Shutdown( void );
void fill_triangle_buffer( void );
struct triangle {
float color[ 3 ];
float p1[ 3 ];
float p2[ 3 ];
float p3[ 3 ];
};
struct triangle triangles[ 12 ];
static double GetMilliseconds() {
static timeval s_tTimeVal;
gettimeofday(&s_tTimeVal, NULL);
double time = s_tTimeVal.tv_sec * 1000.0; // sec to ms
time += s_tTimeVal.tv_usec / 1000.0; // us to ms
return time;
}
GLuint loadBMP_custom( const char * imagepath ) {
// Data read from the header of the BMP file
unsigned char header[54]; // Each BMP file begins by a 54-bytes header
unsigned int dataPos; // Position in the file where the actual data begins
unsigned int width, height;
unsigned int imageSize; // = width*height*3
// Actual RGB data
unsigned char * data;
// Open the file
FILE * file = fopen(imagepath,"rb");
if (!file) {
printf("Image could not be opened\n");
return 0;
}
if ( fread(header, 1, 54, file)!=54 ){ // If not 54 bytes read : problem
printf("Not a correct BMP file\n");
return false;
}
if ( header[0]!='B' || header[1]!='M' ){
printf("Not a correct BMP file\n");
return 0;
}
// Read ints from the byte array
dataPos = *(int*)&(header[0x0A]);
imageSize = *(int*)&(header[0x22]);
width = *(int*)&(header[0x12]);
height = *(int*)&(header[0x16]);
// Some BMP files are misformatted, guess missing information
if (imageSize==0)
imageSize=width*height*3; // 3 : one byte for each Red, Green and Blue component
if (dataPos==0)
dataPos=54; // The BMP header is done that way
// Create a buffer
data = new unsigned char [imageSize];
// Read the actual data from the file into the buffer
fread(data,1,imageSize,file);
//Everything is in memory now, the file can be closed
fclose(file);
// Create one OpenGL texture
GLuint textureID;
glGenTextures(1, &textureID);
// "Bind" the newly created texture : all future texture functions will modify this texture
glBindTexture(GL_TEXTURE_2D, textureID);
// Give the image to OpenGL
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_BGR, GL_UNSIGNED_BYTE, data);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_MIRRORED_REPEAT);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_MIRRORED_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
// return GLuint
return textureID;
}
int main (int argc, char ** argv){
Display *dpy = XOpenDisplay(0);
Window win;
XEvent ev;
int nelements;
GLXFBConfig *fbc = glXChooseFBConfig(dpy, DefaultScreen(dpy), 0, &nelements);
static int attributeList[] = { GLX_RGBA, GLX_DOUBLEBUFFER, GLX_RED_SIZE, 1, GLX_GREEN_SIZE, 1, GLX_BLUE_SIZE, 1, None };
XVisualInfo *vi = glXChooseVisual(dpy, DefaultScreen(dpy),attributeList);
// Set Window attributes
XSetWindowAttributes swa;
swa.colormap = XCreateColormap(dpy, RootWindow(dpy, vi->screen), vi->visual, AllocNone);
swa.border_pixel = 0;
swa.event_mask = StructureNotifyMask;
win = XCreateWindow(dpy, RootWindow(dpy, vi->screen), 0, 0, WINDOW_WIDTH, WINDOW_HEIGHT, 0, vi->depth, InputOutput, vi->visual, CWBorderPixel|CWColormap|CWEventMask, &swa);
// Select window inputs to be triggered in the eventlistener
XSelectInput( dpy, win, PointerMotionMask | ButtonPressMask | ButtonReleaseMask | KeyPressMask );
XMapWindow (dpy, win);
//oldstyle context:
// GLXContext ctx = glXCreateContext(dpy, vi, 0, GL_TRUE);
std::cout << "glXCreateContextAttribsARB " << (void*) glXGetProcAddress((const GLubyte*)"glXCreateContextAttribsARB") << std::endl;
GLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribsARB = (GLXCREATECONTEXTATTRIBSARBPROC) glXGetProcAddress((const GLubyte*)"glXCreateContextAttribsARB");
int attribs[] = {
GLX_CONTEXT_MAJOR_VERSION_ARB, 3,
GLX_CONTEXT_MINOR_VERSION_ARB, 0,
0};
// Redirect Close
Atom atomWmDeleteWindow = XInternAtom(dpy, "WM_DELETE_WINDOW", False);
XSetWMProtocols(dpy, win, &atomWmDeleteWindow, 1);
// Create GLX OpenGL context
GLXContext ctx = glXCreateContextAttribsARB(dpy, *fbc, 0, true, attribs);
glXMakeCurrent( dpy, win, ctx );
glMatrixMode( GL_PROJECTION );
glEnable( GL_CULL_FACE );
glCullFace( GL_FRONT );
glFrustum( -1, 1, 1, -1, -1, 1 );
glClearColor (0, 0.5, 1, 1);
glClear (GL_COLOR_BUFFER_BIT);
glXSwapBuffers (dpy, win);
fill_triangle_buffer();
// Load and bind texture
glEnable(GL_TEXTURE_2D);
loadBMP_custom("textures/texture.bmp");
// prepare gameloop
double prevTime = GetMilliseconds();
double currentTime = GetMilliseconds();
double deltaTime = 0.0;
timeval time;
long sleepTime = 0;
gettimeofday(&time, NULL);
long nextGameTick = (time.tv_sec * 1000) + (time.tv_usec / 1000);
while ( shutdown != 1 ) {
// Get events if there is any
if (XPending(dpy) > 0) {
XNextEvent(dpy, &ev);
if (ev.type == Expose) {
XWindowAttributes attribs;
XGetWindowAttributes(dpy, win, &attribs);
Resize(attribs.width, attribs.height);
}
if (ev.type == ClientMessage) {
if (ev.xclient.data.l[0] == atomWmDeleteWindow) {
break;
}
}
else if (ev.type == DestroyNotify) {
break;
}
}
// Framelimit calculations, before heavy load
currentTime = GetMilliseconds();
deltaTime = double( currentTime - prevTime ) * 0.001;
prevTime = currentTime;
// Do work
HandleEvents( ev );
//Render();
glClear( GL_COLOR_BUFFER_BIT );
glBegin(GL_TRIANGLES);
glColor3f( 255, 255, 255 );
/*
glTexCoord2f( 0.0f, 1.0f );
glVertex3f( -0.5f, 0.5f, 0.0f );
glTexCoord2f( 1.0f, 1.0f );
glVertex3f( 0.5f, 0.5f, 0.0f );
glTexCoord2f( 0.0f, 0.0f );
glVertex3f( -0.5f, -0.5f, 0.0f );
glVertex3f( 0.5f, 0.5f, 0.0f );
glTexCoord2f( 1.0f, 0.0f );
glVertex3f( 0.5f, -0.5f, 0.0f );
glVertex3f( -0.5f, -0.5f, 0.0f );
*/
// first triangle, bottom left half
glTexCoord2f( 0.0f, 0.0f ); glVertex3f( -0.5f, -0.5f, 0 );
glTexCoord2f( 0.0f, 1.0f ); glVertex3f( -0.5f, 0.5f, 0 );
glTexCoord2f( 1.0f, 0.0f ); glVertex3f( 0.5f, -0.5f, 0 );
// second triangle, top right half
glTexCoord2f( 1.0f, 0.0f ); glVertex3f( 0.5f, -0.5f, 0 );
glTexCoord2f( 0.0f, 1.0f ); glVertex3f( -0.5f, 0.5f, 0 );
glTexCoord2f( 1.0f, 1.0f ); glVertex3f( 0.5f, 0.5f, 0 );
glEnd();
glFlush();
glXSwapBuffers( dpy, win );
// Limit Framerate
gettimeofday( &time, NULL );
nextGameTick += SKIP_TICKS;
sleepTime = nextGameTick - ( (time.tv_sec * 1000) + (time.tv_usec / 1000) );
usleep((unsigned int)(sleepTime/1000));
}
ctx = glXGetCurrentContext();
glXDestroyContext(dpy, ctx);
}
void fill_triangle_buffer( void ){
triangles[ 0 ] = {
{ 1.0f, 0.0f, 0.0f },
{ -0.5f, -0.5f, -0.5f },
{ 0.5f, 0.5f, -0.5f },
{ 0.5f, -0.5f, -0.5f } };
triangles[ 1 ] = {
{ 0.0f, 0.0f, 1.0f },
{ -0.5f, -0.5f, -0.5f },
{ -0.5f, 0.5f, -0.5f },
{ 0.5f, 0.5f, -0.5f } };
triangles[ 2 ] = {
{ 0.0f, 0.0f, 1.0f },
{ 0.5f, 0.5f, -0.5f },
{ 0.5f, -0.5f, 0.5f },
{ 0.5f, -0.5f, -0.5f } };
triangles[ 3 ] = {
{ 1.0f, 1.0f, 0.0f },
{ 0.5f, 0.5f, -0.5f },
{ 0.5f, 0.5f, 0.5f },
{ 0.5f, -0.5f, 0.5f } };
triangles[ 4 ] = {
{ 1.0f, 0.0f, 0.0f },
{ -0.5f, -0.5f, 0.5f },
{ 0.5f, -0.5f, 0.5f },
{ -0.5f, 0.5f, 0.5f } };
triangles[ 5 ] = {
{ 0.0f, 0.0f, 1.0f },
{ 0.5f, -0.5f, 0.5f },
{ 0.5f, 0.5f, 0.5f },
{ -0.5f, 0.5f, 0.5f } };
triangles[ 6 ] = {
{ 0.0f, 0.0f, 1.0f },
{ -0.5f, 0.5f, -0.5f },
{ -0.5f, -0.5f, 0.5f },
{ -0.5f, 0.5f, 0.5f } };
triangles[ 7 ] = {
{ 1.0f, 1.0f, 0.0f },
{ -0.5f, 0.5f, -0.5f },
{ -0.5f, -0.5f, -0.5f },
{ -0.5f, -0.5f, 0.5f } };
triangles[ 8 ] = {
{ 1.0f, 0.0f, 0.0f },
{ -0.5f, 0.5f, -0.5f },
{ -0.5f, 0.5f, 0.5f },
{ 0.5f, 0.5f, 0.5f } };
triangles[ 9 ] = {
{ 0.0f, 0.0f, 1.0f },
{ -0.5f, 0.5f, -0.5f },
{ 0.5f, 0.5f, 0.5f },
{ 0.5f, 0.5f, -0.5f } };
triangles[ 10 ] = {
{ 0.0f, 0.0f, 1.0f },
{ 0.5f, -0.5f, -0.5f },
{ 0.5f, -0.5f, 0.5f },
{ -0.5f, -0.5f, 0.5f } };
triangles[ 11 ] = {
{ 1.0f, 1.0f, 0.0f },
{ 0.5f, -0.5f, -0.5f },
{ -0.5f, -0.5f, 0.5f },
{ -0.5f, -0.5f, -0.5f } };
}
void Resize(int w, int h) {
glViewport(0, 0, w, h);
}
void Shutdown() {
shutdown = 1;
}
void Render( void ) {
glClearColor ( 1.0f, 1.0f, 1.0f, 1 );
glClear( GL_COLOR_BUFFER_BIT );
glBegin(GL_TRIANGLES);
/*glColor3f( 0.0f, 1.0f, 0.0f );
glVertex3f( test_cnt, 0.0f, 1.0f );
glVertex3f( 1.0f, 0.0f, 1.0f );
glVertex3f( 0.0f, -1.0f, 1.0f );
*/
int numTriangles = sizeof(triangles)/sizeof(triangles[0]);
for ( int i = 0; i < numTriangles; i++ ) {
glClear( GL_COLOR_BUFFER_BIT );
glBegin(GL_TRIANGLES);
struct triangle tr = triangles[ i ];
glColor3f( tr.color[ 0 ], tr.color[ 1 ], tr.color[ 2 ] );
glVertex3f( tr.p1[ 0 ], tr.p1[ 1 ], tr.p1[ 2 ] );
glVertex3f( tr.p2[ 0 ], tr.p2[ 1 ], tr.p2[ 2 ] );
glVertex3f( tr.p3[ 0 ], tr.p3[ 1 ], tr.p3[ 2 ] );
}
glEnd();
glFlush();
}
float dx, dy;
float prevx, prevy;
uint8_t prev_defined = 0;
uint8_t key_down = 0;
void HandleEvents( XEvent ev ) {
int x, y;
switch ( ev.type ) {
case ButtonPress:
if ( ev.xbutton.button == 1 ) {
std::cout << "Left mouse down \n";
// glRotatef( 0.01, 0.0, 0.0, 1.0 );
if ( key_down == 0 )
prev_defined = 0;
key_down = 1;
}
break;
case ButtonRelease:
if ( ev.xbutton.button == 1 ) {
std::cout << "Left mouse up \n";
key_down = 0;
}
break;
case KeyPress:
if ( ev.xkey.keycode == 9 ) { // ESC
Shutdown();
}
break;
case MotionNotify:
x = ev.xmotion.x;
y = ev.xmotion.y;
if ( key_down == 0 )
break;
if ( !prev_defined ) {
prevx = x;
prevy = y;
prev_defined = 1;
break;
}
dx = x - prevx;
dy = y - prevy;
prevx = x;
prevy = y;
glRotatef( -dy/10, 1.0f, 0.0f, 0.0f );
glRotatef( -dx/10, 0.0f, 1.0f, 0.0f );
//std::cout << "Mouse X:" << x << ", Y: " << y << "\n";
break;
}
}
I compile with:
g++ -g -Wall -o _build/main main.cpp -I/opt/x11/include -L/usr/x11/lib -lglfw -lGLEW -lGL -lX11
OS:
Linux kali 5.9.0-kali4-amd64 #1 SMP Debian 5.9.11-1kali1 (2020-12-01) x86_64 GNU/Linux
Do anyone know how to resolve this issue in order to completely show above texture on my triangles?
