Simple vertex manipulation question

[Seraphis]

O.K. So I've been learning OpenGL and I was messing around with drawing shapes when I got the idea of making a triangle, which could via the W,A,S,D keys have its vertices moved about the screen to reshape it.

I got it working with 1 vertex, just by making a GLfloat , and manipulating it with



if (keys['S']) { blah blah }


The idea I came up with to make a multidimensional array which used a variable in the brackets to change the vertex every time the user hits enter.... Heres what I got.

**My Variables**


GLfloat p1[10];
GLfloat p2[10];
GLfloat p3[10];
int stc=0;



int DrawGLScene(GLvoid)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();

glTranslatef(0,0,0);

glRotatef(rtri,0.0f,1.0f,0.0f);
glRotatef(rtriz,1.0f,0.0f,0.0f);

glBegin(GL_TRIANGLES);
glVertex3f(p1[0],p2[0],p3[0]);
glVertex3f(p1[1],p2[1],p3[1]);
glVertex3f(p1[2],p2[2],p3[2]);
glEnd();

if (keys['W'])
{
keys['W'] = FALSE;
p1[stc]+=0.1f;
}
if (keys['S'])
{
keys['S'] = FALSE;
p1[stc]-=0.1f;
}
if (keys[VK_RETURN])
{
if (stc < 3)
{
stc++;
}
else if (stc > 2)
{
stc = 0;
}
}

return TRUE; //
}


In theory, this should make it so you can cycle through the 3 vertices and moved the X position, positive or negative.

I get no errors when I compile it, but when I run it theres no triangle... which makes sense considering all of the points on it are 0.0f . But when I push 'W' to bring the 1st vertex up, nothing happens.

Thoughts?

Thx in advance,
Seraphis

[Zachm]

Can you post your Init code part, or simply the entire code, if not too long ?

[Gluon]

hi seraphis!

at first: Zachm is right. You need to make sure, that the camera points at the right place and that you've chosen the correct colors etc (can't see black on black for example...). For this we need the other parts...

second:
I think you should replace



if (stc < 3)
{
stc++;
}
else if (stc > 2)
{
stc = 0;
}



which cycles 0 1 2 3 0 1 2 3 0 1 2 3... by the shorter and nicer


stc = (++stc) % 3;


which cycles 0 1 2 0 1 2 0 1 2... through the three (instead of four) points.