Loic wrote:
> You are right...
> I guess it can't be in the constructor because OpenGL is not yet necessary
> started up at constructor time...
Correct -- all opengl init should be done inside the
draw() 'if (!valid())' test.
Pretty sure the docs for Fl_Gl_Window and the "Using OpenGL"
cover the reasoning behind this, though it probably needs
to be made clearer.
A documentation overhaul of sorts has been in the works,
I'll see if we can make this a little more explicit in
both the above pages.
> for your other comments, I ofcourse agree on it...
> But this was just a dummy example, just to check my texture problem...
> My project is of course better code than this ;)
Right, as I looked at your code, I could tell snippets
were being moved around to try to make things work..
Must've been maddening cause you knew your glut version
worked right.
FWIW, I took one of my offline examples, and merged in
your cube object in place of what I had (a spinning square),
which makes it a better example.
This has the timer, a perspective frustum, and a
"checkerboard" pattern for the texturemap.
If you want, I can added this as an example on my
'cheat page' of FLTK demo examples..
* * *
#include <stdio.h>
#include <math.h>
#include <FL/Fl.h>
#include <FL/Fl_Window.h>
#include <FL/Fl_Gl_Window.h>
#include <FL/gl.h>
//
// OpenGL spinning cube with checker texturemap -- erco/loic 03/17/09
//
#define WIN_W 400 // window width
#define WIN_H 400 // window height
#define TEX_W 64 // texturemap width
#define TEX_H 64 // texturemap height
#define FPS (1.0/24.0) // frames per second playback
//
// OpenGL class to show texturemapped cube
//
class MyGlWindow : public Fl_Gl_Window {
double spin;
GLuint TexID;
// TIMER CALLBACK
// Handles rotation the object
//
static void Timer_CB(void *userdata) {
MyGlWindow *mygl = (MyGlWindow*)userdata;
mygl->spin += 2.0; // spin
mygl->redraw();
Fl::repeat_timeout(FPS, Timer_CB, userdata);
}
public:
// CTOR
MyGlWindow(int x,int y,int w,int h,const char *l=0) : Fl_Gl_Window(x,y,w,h,l)
{
spin = 0.0;
Fl::add_timeout(FPS, Timer_CB, (void*)this); // 24fps timer
}
// PERSPECTIVE VIEW
// Same as gluPerspective()..
//
void Perspective(GLdouble fovy, GLdouble aspect, GLdouble zNear, GLdouble
zFar) {
GLdouble xmin, xmax, ymin, ymax;
ymax = zNear * tan(fovy * M_PI / 360.0);
ymin = -ymax;
xmin = ymin * aspect;
xmax = ymax * aspect;
glFrustum(xmin, xmax, ymin, ymax, zNear, zFar);
}
// RESHAPED VIEWPORT
// OpenGL stuff to do whenever window changes size
//
void ReshapeViewport() {
// Viewport
glViewport(0, 0, w(), h());
// Projection
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
GLfloat ratio = w() / h();
Perspective(30.0, 1.0*ratio, 1.0, 30.0);
glTranslatef(0.0, 0.0, -8.0);
// Model view
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
}
// OPENGL INITIALIZATION
// OpenGL stuff to do *only once* on startup.
//
void GlInit() {
// Make sure we only do this once
static int first_time = 1;
if ( first_time ) {
first_time = 0;
// Texture Map Init
GLubyte img[TEX_W][TEX_H][3]; // after glTexImage2D(), array
is no longer needed
glGenTextures(1, &TexID);
glBindTexture(GL_TEXTURE_2D, TexID);
for (int x=0; x<TEX_W; x++) {
for (int y=0; y<TEX_H; y++) {
GLubyte c = ((x&16)^(y&16)) ? 255 : 0;
// checkerboard
//GLubyte c = ((x&16)^(y&16)) ? ((x%16)<<4) : (((x%16)^15)<<4);
// basket weave
img[x][y][0] = c;
img[x][y][1] = c;
img[x][y][2] = c;
}
}
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, TEX_W, TEX_H, 0, GL_RGB,
GL_UNSIGNED_BYTE, &img[0][0][0]);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glEnable(GL_TEXTURE_2D);
// Misc OpenGL settings
glShadeModel(GL_FLAT);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
}
}
// FLTK DRAW
// Called by FLTK to draw the scene.
//
void draw() {
// Initialize/handle reshaped viewport
if ( !valid() ) {
valid(1);
GlInit();
ReshapeViewport();
}
// Clear
glClearColor(.5,.5,.5, 0.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
// Setup model matrix
glLoadIdentity();
glRotatef(spin, 0.5, 1.0, 0.0); // show all sides of cube
// Draw cube with texture assigned to each face
glBegin(GL_QUADS);
// Front Face
glColor3f(1.0, 0.0, 0.0); // red
glTexCoord2f(0.0, 1.0); glVertex3f(-1.0, 1.0, 1.0); // Top
Left Of The Texture and Quad
glTexCoord2f(1.0, 1.0); glVertex3f( 1.0, 1.0, 1.0); // Top
Right Of The Texture and Quad
glTexCoord2f(1.0, 0.0); glVertex3f( 1.0, -1.0, 1.0); //
Bottom Right Of The Texture and Quad
glTexCoord2f(0.0, 0.0); glVertex3f(-1.0, -1.0, 1.0); //
Bottom Left Of The Texture and Quad
// Back Face
glColor3f(0.0, 1.0, 1.0); // cyn
glTexCoord2f(0.0, 1.0); glVertex3f( 1.0, 1.0, -1.0); // Top
Left Of The Texture and Quad
glTexCoord2f(1.0, 1.0); glVertex3f(-1.0, 1.0, -1.0); // Top
Right Of The Texture and Quad
glTexCoord2f(1.0, 0.0); glVertex3f(-1.0, -1.0, -1.0); //
Bottom Right Of The Texture and Quad
glTexCoord2f(0.0, 0.0); glVertex3f( 1.0, -1.0, -1.0); //
Bottom Left Of The Texture and Quad
// Top Face
glColor3f(0.0, 1.0, 0.0); // grn
glTexCoord2f(0.0, 1.0); glVertex3f(-1.0, 1.0, -1.0); // Top
Left Of The Texture and Quad
glTexCoord2f(1.0, 1.0); glVertex3f( 1.0, 1.0, -1.0); // Top
Right Of The Texture and Quad
glTexCoord2f(1.0, 0.0); glVertex3f( 1.0, 1.0, 1.0); //
Bottom Right Of The Texture and Quad
glTexCoord2f(0.0, 0.0); glVertex3f(-1.0, 1.0, 1.0); //
Bottom Left Of The Texture and Quad
// Bottom Face
glColor3f(1.0, 0.0, 1.0); // mag
glTexCoord2f(0.0, 1.0); glVertex3f( 1.0, -1.0, -1.0); // Top
Left Of The Texture and Quad
glTexCoord2f(1.0, 1.0); glVertex3f(-1.0, -1.0, -1.0); // Top
Right Of The Texture and Quad
glTexCoord2f(1.0, 0.0); glVertex3f(-1.0, -1.0, 1.0); //
Bottom Right Of The Texture and Quad
glTexCoord2f(0.0, 0.0); glVertex3f( 1.0, -1.0, 1.0); //
Bottom Left Of The Texture and Quad
// Right face
glColor3f(0.0, 0.0, 1.0); // blu
glTexCoord2f(0.0, 1.0); glVertex3f( 1.0, 1.0, 1.0); // Top
Left Of The Texture and Quad
glTexCoord2f(1.0, 1.0); glVertex3f( 1.0, 1.0, -1.0); // Top
Right Of The Texture and Quad
glTexCoord2f(1.0, 0.0); glVertex3f( 1.0, -1.0, -1.0); //
Bottom Right Of The Texture and Quad
glTexCoord2f(0.0, 0.0); glVertex3f( 1.0, -1.0, 1.0); //
Bottom Left Of The Texture and Quad
// Left Face
glColor3f(1.0, 1.0, 0.0); // yel
glTexCoord2f(0.0, 1.0); glVertex3f(-1.0, 1.0, -1.0); // Top
Left Of The Texture and Quad
glTexCoord2f(1.0, 1.0); glVertex3f(-1.0, 1.0, 1.0); // Top
Right Of The Texture and Quad
glTexCoord2f(1.0, 0.0); glVertex3f(-1.0, -1.0, 1.0); //
Bottom Right Of The Texture and Quad
glTexCoord2f(0.0, 0.0); glVertex3f(-1.0, -1.0, -1.0); //
Bottom Left Of The Texture and Quad
glEnd();
// DEBUG: CHECK FOR ERRORS
GLenum err = glGetError();
if ( err != GL_NO_ERROR ) {
fprintf(stderr, "GLGETERROR=%d\n", (int)err);
}
}
};
int main(int argc, char *argv[]) {
MyGlWindow* mygl = new MyGlWindow(10, 10, WIN_W-20, WIN_H-20, "Texture Test");
mygl->end();
mygl->resizable(mygl);
mygl->show();
return(Fl::run());
}
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