Hi there,
I have a (2D) app running in Windows 2k. The app used to be in colour indexed mode. When I converted it to RGB, several weird things started happening. I’ll list them, plus anything I think may be relevant;
Problems:
-
The biggest problem is that when my desktop is in 24 bpp, the speed of the program drops dramatically. The speed is OK for 8 and 16 bpp display modes.
-
The next biggest problem is that when my desktop is in 16 or 24 bpp, the lines drawn with glBegin(GL_LINES) aren’t being drawn as sharp - it’s only noticeable when the lines aren’t vertical or horizontal, but they’re definitely thicker than they were in colour indexed mode. I thought maybe this is something to do with anti-aliasing, but to my knowledge I’ve not turned it on. The only possibly relevant calls I make are glClearColor(0.0, 0.0, 0.0, 0.0); glShadeModel(GL_FLAT); in my init().
-
I’m drawing several box outlines like this:
Draw_Line(border.x(),border.y(), border.x() + size.x(), border.y(), colour);
Draw_Line(border.x() + size.x(), border.y(), border.x() + size.x(), border.y() + size.y(), colour);
Draw_Line(border.x() + size.x(), border.y() + size.y(), border.x(), border.y() + size.y(), colour);
Draw_Line(border.x(), border.y() + size.y(), border.x(), border.y(), colour);
When my desktop is in 16 or 24 bpp, the top-left pixel of each box is missing. Sometimes it’s the lower-right pixel which goes AWOL. This does not happen when I run the program in colour indexed mode – but then I can only test it in an 8 bpp display mode when I am in colour indexed mode – and the problem doesn’t occur in 8 bpp modes, regardless. -
Finally, when my desktop is in 24 bpp only, the mouse is flickering when over the window. This is really the least of my worries!
Here is my Draw_Line;
void Draw_Line(int x1, int y1, int x2, int y2, GLfloat *colour)
{
glColor3fv(colour);
glBegin(GL_LINES);
glVertex2f(x1, y1);
glVertex2f(x2, y2);
glEnd();
}
This is basically the only drawing command in the program – the entire program just consists of a hundred or so lines being drawn in an animation (a set of 2D stick characters pretending to walk along). I tried using vertex arrays for the coordinates and the colours, but this didn’t help either – in both the speed and the line-drawing problem.
Only a few colours are used. They are defined as follows:
GLfloat red[] = {1.0, 0.0, 0.0}, green[] = {0.0, 1.0, 0.0}, blue[] = {0.0, 0.0, 1.0}, white[] = {1.0, 1.0, 1.0}, darkred[] = {0.5, 1.0, 1.0};
I thought maybe I’m doing something wrong with the arrays – my C isn’t great – and so I replaced the glColor3fv() in Draw_Line with glColor3f(1.0, 1.0, 1.0) as a test – but this made no difference.
I’ve also got a couple of text-printing functions:
void Draw_Text(char *s, int x, int y, GLfloat *colour)
{
glRasterPos2f(x, y + 12);
glColor3f(1.0, 1.0, 1.0); //glColor3fv(colour);
while (*s)
glutBitmapCharacter(GLUT_BITMAP_HELVETICA_12, (int) *s++);
}
void Draw_Text(const std::string& s, Point loc, GLfloat *colour)
{
char *buf, *top;
buf = (char *) malloc(sizeof(char) * ((s.size() + 1)));
strcpy(buf, s.c_str());
top = buf;
glRasterPos2f(loc.x(), loc.y() + 12);
glColor3f(1.0, 1.0, 1.0); //glColor3fv(colour);
while (*buf)
glutBitmapCharacter(GLUT_BITMAP_HELVETICA_12, (int) *buf++);
free(top);
}
I tried commenting out the contents of both of these functions, to eliminate text-printing from causing the problem – but doing so slowed the program down even further – this I have no idea why it’s happening!
Finally, here is my entire main.cpp:
#include <ctime>
#include <GL/glut.h>
#include “Justlegs.h”
#include “util.h”
#include “ea.h”
// the main application object
Justlegs *justlegs;
void init()
{
// build the 360 degree look ups
build_sin_cos_tables();
//build_palette();
glClearColor(0.0, 0.0, 0.0, 0.0);
glShadeModel(GL_FLAT);
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
glColorPointer(3, GL_FLOAT, 0, colours);
glVertexPointer(2, GL_INT, 0, coords);
screen_width = 640;
screen_height = 480;
aspect_mult_x = aspect_mult_y = 1;
fullscreen = false;
srand((unsigned long) time(NULL));
// construct our application object with parameters from ea.h
justlegs = new Justlegs(POP_SIZE, INTERVAL, CONTROL_POINTS, SAMPLE_SIZE);
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
// this projection inverts the y axis because the code thinks (0,0)
// is in the top-right - this is a legacy of its DirectDraw roots...
gluOrtho2D(0.0, (GLfloat) screen_width, (GLfloat) screen_height, 0.0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
justlegs->run();
Draw_Arrays();
glFlush();
glutSwapBuffers();
}
void keyboard(unsigned char key, int x, int y)
{
// escape
if (key == 27)
if (!justlegs->pop_state())
exit(0);
// tab
if (key == 9) {
if (!fullscreen)
glutFullScreen();
else {
glutPositionWindow(50, 50);
glutReshapeWindow(640, 480);
}
fullscreen = !fullscreen;
}
}
void mouse(int button, int state, int x, int y)
{
Point loc(x * aspect_mult_x, y * aspect_mult_y);
justlegs->notify(button, state, loc);
}
void idle()
{
justlegs->run();
glutPostRedisplay();
}
void reshape(int w, int h)
{
glViewport(0, 0, (GLsizei) w, (GLsizei) h);
aspect_mult_x = (double) glutGet(GLUT_INIT_WINDOW_WIDTH)
/ glutGet(GLUT_WINDOW_WIDTH);
aspect_mult_y = (double) glutGet(GLUT_INIT_WINDOW_HEIGHT)
/ glutGet(GLUT_WINDOW_HEIGHT);
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGB);
glutInitWindowSize(640, 480);
glutInitWindowPosition(50, 50);
glutCreateWindow(“Walker”);
init();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc(keyboard);
glutMouseFunc(mouse);
glutIdleFunc(idle);
glutMainLoop();
return 0;
}
If anyone can help, I’d really appreciate it.
Many thanks in advance,
Darren
