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nickme

2D texture does not render correctly.

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hi,

i am writing a fractal program. i want to load a png file as a splash screen. i used texture 2d to read and display on the screen. i suspect the loadTexture2D function do not work correctly. i hope some one can point out what i do wrong.

thanks.
#include <math.h>
#include <stdio.h>
#include <gl/glut.h>
GLuint SplashScreen;
const GLint win_sizeX = 1904, win_sizeY = 1000;
const GLdouble w = 1024.0, h = 1024.0; // margins.
const GLdouble wleft = -w *0.5, wright = w *0.5, wtop = h /2, wbottom = - h/2;
void clear()
{
glClearColor(1.0, 1.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT);
}
GLuint LoadTexture2D( const char * filename, int width, int height)
{
GLuint texture;
FILE * file;
file = fopen( filename, "rb" );
if ( file == NULL ) {
system("PAUSE");
exit(1);
}
GLubyte * data = new unsigned char [width * height * 3]; // texture data for color bar file
fread( data, 1, width * height * 3, file );
fclose( file );
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glGenTextures( 1, &texture );
glBindTexture( GL_TEXTURE_2D, texture );
glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);
delete [] data;
return texture;
}
void display_splash_screen(int time)
{
clear();
glEnable( GL_TEXTURE_2D );
glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
glBindTexture( GL_TEXTURE_2D, SplashScreen);
glBegin( GL_QUADS );

glTexCoord2d(0.0,0.0); glVertex2d(wleft + 20, wtop-20);
glTexCoord2d(1.0,0.0); glVertex2d(wright -20, wtop -20);
glTexCoord2d(1.0,1.0); glVertex2d(wright -20, wbottom + 20);
glTexCoord2d(0.0,1.0); glVertex2d(wleft + 20, wbottom + 20);

glEnd();
glFlush();
Sleep(time);
}
void init()
{
glDisable(GL_CULL_FACE);
glDisable(GL_DEPTH_TEST);
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
SplashScreen = LoadTexture2D("SplashScreen.png", w, h);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
}
void render() {
clear();
display_splash_screen(0);
}
void winReshapeFcn(GLint newWidth, GLint newHeight)
{
glutReshapeWindow(w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(wleft, wright, wbottom, wtop);
glMatrixMode(GL_MODELVIEW);
}
void processNormalKeys(unsigned char key, int x, int y)
{
if (key == 27)
exit(0);
}
int main(int argc, char** argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowPosition(0, 0);
glutInitWindowSize(win_sizeX, win_sizeY);
glutCreateWindow(" Texture testing by ");
init();
glutIgnoreKeyRepeat(0);
glutReshapeFunc(winReshapeFcn);
glutDisplayFunc(render);
glutKeyboardFunc(processNormalKeys);
glutMainLoop();
glDeleteTextures(1, &SplashScreen);
return 0;
} Edited by nickme

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hi

please note: the top of the window shows some random colors.

for moderator: i got a message from my last post that i should use the red {...} when including source codes, how do i do that? click the {...} before or after pasting the code into the editor?

thanks

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hi,
i reload the code here. sorry.
[source lang="java"]#include <math.h>
#include <stdio.h>
#include <gl/glut.h>
GLuint SplashScreen;

const GLint win_sizeX = 1904, win_sizeY = 1000;
const GLdouble w = 1024.0, h = 1024.0; // margins.
const GLdouble wleft = -w *0.5, wright = w *0.5, wtop = h /2, wbottom = - h/2;

void clear()
{
glClearColor(1.0, 1.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT);
}

GLuint LoadTexture2D( const char * filename, int width, int height)
{
GLuint texture;
FILE * file;

file = fopen( filename, "rb" );
if ( file == NULL ) {
system("PAUSE");
exit(1);
}

GLubyte * data = new unsigned char [width * height * 3]; // texture data for color bar file

fread( data, 1, width * height * 3, file );
fclose( file );
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glGenTextures( 1, &texture );

glBindTexture( GL_TEXTURE_2D, texture );

glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);

glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height, 0, GL_RGB, GL_UNSIGNED_BYTE, data);

delete [] data;
return texture;
}

void display_splash_screen(int time)
{
clear();
glEnable( GL_TEXTURE_2D );
glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
glBindTexture( GL_TEXTURE_2D, SplashScreen);

glBegin( GL_QUADS );

glTexCoord2d(0.0,0.0); glVertex2d(wleft + 20, wtop-20);
glTexCoord2d(1.0,0.0); glVertex2d(wright -20, wtop -20);
glTexCoord2d(1.0,1.0); glVertex2d(wright -20, wbottom + 20);
glTexCoord2d(0.0,1.0); glVertex2d(wleft + 20, wbottom + 20);

glEnd();
glFlush();
Sleep(time);
}

void init()
{

glDisable(GL_CULL_FACE);
glDisable(GL_DEPTH_TEST);

glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
SplashScreen = LoadTexture2D("SplashScreen.png", w, h);

glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
}

void render() {
clear();
display_splash_screen(0);
}

void winReshapeFcn(GLint newWidth, GLint newHeight)
{
glutReshapeWindow(w, h);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
gluOrtho2D(wleft, wright, wbottom, wtop);
glMatrixMode(GL_MODELVIEW);
}

void processNormalKeys(unsigned char key, int x, int y)
{
if (key == 27)
exit(0);
}

int main(int argc, char** argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
glutInitWindowPosition(0, 0);
glutInitWindowSize(win_sizeX, win_sizeY);
glutCreateWindow(" Texture testing");

init();
glutIgnoreKeyRepeat(0);
glutReshapeFunc(winReshapeFcn);
glutDisplayFunc(render);
glutKeyboardFunc(processNormalKeys);

glutMainLoop();
glDeleteTextures(1, &SplashScreen);

return 0;
}
[/source] Edited by nickme

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[CODE]
fread( data, 1, width * height * 3, file );
fclose( file );
[/CODE]

Here's your problem, you can't read directly from a png file, it's compressed. You need to decompress it first in order to get any useful data. I would recommend using an image loading library like [url="http://freeimage.sourceforge.net/"]FreeImage[/url] or [url="http://www.lonesock.net/soil.html"]SOIL[/url].

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[quote name='ic0de' timestamp='1353556739' post='5003110']
[CODE]
fread( data, 1, width * height * 3, file );
fclose( file );
[/CODE]

Here's your problem, you can't read directly from a png file, it's compressed. You need to decompress it first in order to get any useful data. I would recommend using an image loading library like [url="http://freeimage.sourceforge.net/"]FreeImage[/url] or [url="http://www.lonesock.net/soil.html"]SOIL[/url].
[/quote]

thanks icOde.

i wonder whether it is compatible with msvc 2010 c++? i tried to load the sln file into vc 2010, but it failed. Edited by nickme

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[quote name='nickme' timestamp='1353599423' post='5003255']
[quote name='ic0de' timestamp='1353556739' post='5003110']
[CODE]
fread( data, 1, width * height * 3, file );
fclose( file );
[/CODE]

Here's your problem, you can't read directly from a png file, it's compressed. You need to decompress it first in order to get any useful data. I would recommend using an image loading library like [url="http://freeimage.sourceforge.net/"]FreeImage[/url] or [url="http://www.lonesock.net/soil.html"]SOIL[/url].
[/quote]

thanks icOde.

i wonder whether it is compatible with msvc 2010 c++? i tried to load the sln file into vc 2010, but it failed.
[/quote]

Which one did you use SOIL or FreeImage? SOIL worked fine for me in vc 2010. You need to compile the VC9 project included with the download, that will generate a static .lib file which you can then link with your code.

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hi icOde:

i tried freeimage. it includes several sln files. from ver vc 2003 to vc 2008. i tried the vc 2008 sln, but vc 2010 said the file is not loaded in the solution explorer.

by the way, do you have any link to website that shows how to install the freeImage to vc 2010?

thanks Edited by nickme

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for freeimage just download "FreeImage DLL" from their site include FreeImage.h link FreeImage.lib and put FreeImage.dll in the same folder as your exe. Documentation for FreeImage can be found here : [url="http://iweb.dl.sourceforge.net/project/freeimage/Source%20Documentation/3.15.4/FreeImage3154.pdf."]http://freeimage.sou...umentation.html[/url]
If you don't know how to link libraries in vs 2010 then I would suggest googling it or opening a new topic. Edited by ic0de

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hi icOde:

i downloaded the freeImage and looked at it, it did not contain all the libraries that was mentioned in the sites that i googled. when i tried to build the vs c++ 2010, the solution explorer say it is unavailable.

i can not find the vc9 file you mentioned from the download file either. i suspect the version that i download is not the one you use. the version i download was 3.15.4.

i also found freeImagePlus. are they related?

thanks Edited by nickme

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