该项目编译运行，但窗口中没有任何显示。
它应该显示一些文本和一个带有一些点的区域。谁能帮我解决这个问题？
这是我的代码:
#include <stdio.h>
#include <windows.h>
#include <GL/gl.h>
#include <glut.h>
#define KEY_ESCAPE 27
#define PROJECTION_WIDTH 150
#define NUMBER_OF_FLIES 50
float xpos[NUMBER_OF_FLIES];
float ypos[NUMBER_OF_FLIES];
typedef struct {
int width;
int height;
char* title;
float field_of_view_angle;
float z_near;
float z_far;
} glutWindow;
glutWindow win;
// To display the text
void renderBitmapString(float x, float y, void *font, const char *string)
{
const char *c;
glRasterPos3f(x, y, 0);
for (c = string; *c != '\0'; c++)
{
glutBitmapCharacter(font, *c);
}
}
void displayText()
{
glPushMatrix();
//glTranslatef(1.0, 0.50, 0.5);
//const int font = (int)GLUT_BITMAP_9_BY_15;
const int font = (int)GLUT_BITMAP_HELVETICA_12;
glColor3f(0.0f, 0.0f, 0.0f); // black color
renderBitmapString(-1.7, 1.3, (void *)font, "1. Load Measured projections");
renderBitmapString(-1.7, 1.2, (void *)font, "2. Set the position of flies, i.e. create initial guess");
renderBitmapString(-1.7, 1.1, (void *)font, "3. Compute projections from the current reconstruction");
renderBitmapString(-1.7, 1, (void *)font, "4. Compute the population's perfomance, i.e. the global fitness");
renderBitmapString(-1.7, 0.9, (void *)font, "5. Select a random fly (fly_to_kill)");
renderBitmapString(-1.7, 0.8, (void *)font, "6. Remove the fly's contribution");
renderBitmapString(-1.7, 0.7, (void *)font, "7. Compute the population's performance without the selected fly");
renderBitmapString(-1.7, 0.6, (void *)font, "8. Compare the performances, i.e. compute the fly's local fitness");
renderBitmapString(-1.7, 0.5, (void *)font, "9. If the local fitness is equal to or greater than the selection threshold,");
renderBitmapString(-1.5, 0.4, (void *)font, "then go to Step 10, ");
renderBitmapString(-1.5, 0.3, (void *)font, "else go to Step 11");
renderBitmapString(-1.7, 0.2, (void *)font, "10. Restore the fly's contribution, then go to Step 5");
renderBitmapString(-1.7, 0.1, (void *)font, "11. Select a genetic operator");
renderBitmapString(-1.7, 0.0, (void *)font, "12. If the genetic operator is mutation,");
renderBitmapString(-1.5, -0.1, (void *)font, "then go to Step 13, ");
renderBitmapString(-1.5, -0.2, (void *)font, "else go to Step 19 ");
renderBitmapString(-1.7, -0.3, (void *)font, "13. Select a random fly (fly_to_reproduce)");
renderBitmapString(-1.7, -0.4, (void *)font, "14. Remove the fly's contribution");
renderBitmapString(-1.7, -0.5, (void *)font, "15. Compute the population's performance without the selected fly");
renderBitmapString(-1.7, -0.6, (void *)font, "16. Compare the performances, i.e. compute the fly's local fitness");
renderBitmapString(-1.7, -0.7, (void *)font, "17. Restore the fly's contribution'");
renderBitmapString(-1.7, -0.8, (void *)font, "18. If the local fitness is smaller than the selection threshold,");
renderBitmapString(-1.5, -0.9, (void *)font, "then go to Step 13, ");
renderBitmapString(-1.5, -1, (void *)font, "else go to Step 20 ");
renderBitmapString(-1.7, -1.1, (void *)font, "19. Replace fly_to_kill by a new fly with a random position, go to Step 22");
renderBitmapString(-1.7, -1.2, (void *)font, "20. Replace fly_to_kill by a new fly based on fly_to_reproduce");
renderBitmapString(-1.7, -1.3, (void *)font, "21. Add the fly's contribution to the population");
renderBitmapString(-1.7, -1.4, (void *)font, "22. If stop the reconstruction,");
renderBitmapString(-1.5, -1.5, (void *)font, "then go to Step 23, ");
renderBitmapString(-1.5, -1.6, (void *)font, "else go to Step 4 ");
renderBitmapString(-1.7, -1.7, (void *)font, "23. Extract good flies");
// the bottom left
renderBitmapString(-3.9, -0.9, (void *)font, "Iterative paradigm for tomography reconstruction");
renderBitmapString(-3.9, -1, (void *)font, "(click here to view the flowchart in full resolution)");
// the top right
renderBitmapString(1.8, 1.3, (void *)font, "Basic Fly algorithm for tomography reconstruction");
renderBitmapString(1.8, 1.2, (void *)font, "(click here to view the flowchart in full resolution)");
glPopMatrix();
glutSwapBuffers();
}
void displayFlies()
{
glPushMatrix();
//glTranslatef(0.0, 0.50, 0.0);
glColor3f(0.0f, 0.0f, 1.0f); //blue color
glPushAttrib(GL_POINT_BIT);
glPointSize(5.0);
// drawing the data
for (int i = 0; i < NUMBER_OF_FLIES; i++){
int DX = xpos[i];
int DY = ypos[i];
glPushMatrix();
//glTranslatef(- 0.85 + DX * 0.014, -1.2 + DY * 0.0135, 0.0);
glBegin(GL_POINTS); // drawing points
glVertex3f(DX, DY, 0.0f);
glEnd();
glPopMatrix();
}
glPopAttrib();
// draw The display Area
glBegin(GL_LINE_LOOP); //start drawing a line loop
glVertex3f(0.65f, 0.25f, 0.0f); //left of window
glVertex3f(0.65f, -1.20f, 0.0f); //bottom of window
glVertex3f(-0.85f, -1.20f, 0.0f); //right of window
glVertex3f(-0.85f, 0.25f, 0.0f); //top of window
glEnd(); //end drawing of line loop
glPopMatrix();
glutSwapBuffers();
}
void displayProjection()
{
glPushMatrix();
//glTranslatef(1.20, 0.50, 0.0);
// The upper rectangle
glBegin(GL_LINE_LOOP); //start drawing a line loop
glVertex3f(0.65f, 0.60f, 0.0f); //left of window
glVertex3f(0.65f, 0.27f, 0.0f); //bottom of window
glVertex3f(-0.85f, 0.27f, 0.0f); //right of window
glVertex3f(-0.85f, 0.60f, 0.0f); //top of window
glEnd();
//The right rectangle
glBegin(GL_LINE_LOOP); //start drawing a line loop
glVertex3f(0.67f, 0.25f, 0.0f); //left of window
glVertex3f(0.67f, -1.20f, 0.0f); //bottom of window
glVertex3f(0.99f, -1.20f, 0.0f); //right of window
glVertex3f(0.99f, 0.25f, 0.0f); //top of window
glEnd(); //end drawing of line loop
// draw Horizontal RED lines
glBegin(GL_LINES);
glColor3f(1.0f, 0.0f, 0.0f);
glVertex3f(-0.25f, 0.60f, 0.0f);
glVertex3f(-0.25f, 0.27f, 0.0f);
glVertex3f(0.1f, 0.27f, 0.0f);
glVertex3f(0.1f, 0.60f, 0.0f);
glEnd();
// draw Upper RED lines
glBegin(GL_LINES);
glVertex3f(0.46f, 0.18f, 0.59f); // origin of the Right line
glVertex3f(0.59f, 0.29f, -0.11f); // ending point of the Right line
glVertex3f(-0.37f, 0.18f, 0.59f); // origin of the Left line
glVertex3f(-0.33f, 0.29f, -0.11f); // ending point of the Left line
glVertex3f(0.37f, 0.40f, 0.92f); // origin of the Upper line
glVertex3f(0.40f, 0.49f, 0.50f); // ending point of the Upper line
glEnd();
// draw Horizontal RED lines
glBegin(GL_LINES);
glVertex3f(-0.06f, 0.47f, -1.50f); // Origin The Upper Horizontal line
glVertex3f(-0.06f, -0.23f, -1.50f); // Ending point of The Upper Horizontal line
glVertex3f(-0.06f, -0.63f, -1.50f); // Origin The bottom Horizontal line
glVertex3f(-0.06f, -1.40f, -1.50f); // Ending point of The bottom Horizontal line
glVertex3f(0.36f, -0.23f, -1.50f); // Origin The right Horizontal line
glVertex3f(0.36f, -0.63f, -1.50f); // Ending point of The right Horizontal line
glVertex3f(0.78f, -0.30f, 0.21f); // origin of the upper vartical line
glVertex3f(0.95f, -0.29f, -0.11f); // ending point of the upper vartical line
glVertex3f(0.78f, -0.60f, 0.21f); // origin of the bottom vartical line
glVertex3f(0.95f, -0.61f, -0.11f); // ending point of the bottom vartical line
glEnd();
glPopMatrix();
}
// intialization function
void initialize()
{
glMatrixMode(GL_PROJECTION); // select projection matrix
glViewport(0, 0, win.width, win.height); // set the viewport
glMatrixMode(GL_PROJECTION); // set matrix mode
glLoadIdentity(); // reset projection matrix
GLfloat aspect = (GLfloat)win.width / win.height;
//gluPerspective(win.field_of_view_angle, aspect, win.z_near, win.z_far); // set up a perspective projection matrix
gluOrtho2D(0, win.width, 0, win.height);
glMatrixMode(GL_MODELVIEW); // specify which matrix is the current matrix
glClearDepth(1.0f); // specify the clear value for the depth buffer
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); // specify implementation-specific hints
glClearColor(1.0f, 1.0f, 1.0f, 1.0f); // specify clear values for the color buffers"background"
}
// keyboard control function
void keyboard(unsigned char key, int mousePositionX, int mousePositionY)
{
switch (key)
{
case KEY_ESCAPE:
exit(0);
break;
default:
break;
}
}
// the main function
int main(int argc, char **argv)
{
// set window values
win.width = 1350;
win.height = 690;
win.title = " The Project ";
win.field_of_view_angle = 45;
win.z_near = 1.0f;
win.z_far = 500.0f;
//initialing the data
for (int i = 0; i < NUMBER_OF_FLIES; i++){
xpos[i] = rand() % PROJECTION_WIDTH;
ypos[i] = rand() % PROJECTION_WIDTH;
}
// initialize and run program
glutInit(&argc, argv); // GLUT initialization
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH); // Display Mode
glutInitWindowSize(win.width, win.height); // set window size
glutCreateWindow(win.title); // create Window
glutDisplayFunc(displayText); // register Display Function
glutIdleFunc(displayText); // register Idle Function
glutDisplayFunc(displayFlies); // register Display Function
glutIdleFunc(displayFlies);
glutDisplayFunc(displayProjection); // register Display Function
glutIdleFunc(displayProjection);
glutKeyboardFunc(keyboard); // register Keyboard Handler
initialize();
glutMainLoop(); // run GLUT mainloop
return 0;
}
最佳答案
你有三个不同的显示函数，但是 glutDisplayFunc 和 glutIdleFunc 只使用你设置的最新的一个，所以 displayText 和 displayFlies 未使用。
最后一个，displayProjection，最后需要一行:
glutSwapBuffers();
此外，您可能需要设置一些灯光来照亮您绘制的内容。
顺便说一句，注释掉其他两个，你可以测试 displayFlies，它呈现一堆蓝点，和 displayText，它写一些文本(黑色在黑色背景上，几条线相互叠加)。
最好先尝试一些教程，例如NeHe ... 是的，正如其他评论员所说，学习着色器可能会更好 :)
关于c++ - 如何使用 OpenGL/GLUT 显示文本和一些点？，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/31371611/