23. OpenGL Camera Part 2
In this opengl camera tutorial you will learn how to incorporate
the mouse using the glut mouse functions, to move our opengl camera like in a first person shooter, along with how to implement the strafe (sideways movement) you see in these games also.
To add the strafe we use:
if (key==’d’)
{
float yrotrad;
yrotrad = (yrot / 180 * 3.141592654f);
xpos += float(cos(yrotrad)) * 0.2;
zpos += float(sin(yrotrad)) * 0.2;
}
if (key==’a’)
{
float yrotrad;
yrotrad = (yrot / 180 * 3.141592654f);
xpos -= float(cos(yrotrad)) * 0.2;
zpos -= float(sin(yrotrad)) * 0.2;
}
You can see that I have simply flipped the cos and sin functions
and set both the xpos and zpos to either a negative or a positive
Now the mouse is a little easier as it uses no trigonometry.
We have to add a function which I have called: mouseMovement
void mouseMovement(int x, int y) {
int diffx=x-lastx; //check the difference between the current x and the last x position
int diffy=y-lasty; //check the difference between the current y and the last y position
lastx=x; //set lastx to the current x position
lasty=y; //set lasty to the current y position
xrot += (float) diffy; //set the xrot to xrot with the addition of the difference in the y position
yrot += (float) diffx;// set the xrot to yrot with the addition of the difference in the x position
}
To get GLUT to register the mouse movements, we call the line:
glutPassiveMotionFunc(mouseMovement);
to see where the mouse is when no mouse button is pressed and call
any functions within our mouseMovement function.
And that does it…
You now know how to add a strafe movement and mouse view.
The next camera tutorial will have lean, jump and duck effects.
If you have any questions, email me at swiftless@gmail.com
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#include <GL/gl.h> #include <GL/glut.h> #include <stdlib.h> #include <math.h> //angle of rotation float lastx, lasty; //positions of the cubes void cubepositions (void) { //set the positions of the cubes //draw the cube void init (void) { void enable (void) { void camera (void) { void display (void) { void reshape (int w, int h) { void keyboard (unsigned char key, int x, int y) { if (key==‘z’) if (key==‘w’) if (key==‘s’) if (key==‘d’) if (key==‘a’) if (key==27) void mouseMovement(int x, int y) { int main (int argc, char **argv) { glutPassiveMotionFunc(mouseMovement); //check for mouse glutKeyboardFunc (keyboard);
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