I'm trying to make one normal out of three verticies. For example this:
glNormal3f(0.0, 0.0, 0.0);
glVertex3f( 0.0, 0.0, 0.0);
glVertex3f( 0.0, 0.0, 0.0);
glVertex3f( 0.0, 0.0, 0.0);

The reason I don't just use GL_FLAT is because I want a smoothed flat plane. What am I doing wrong? Here's the code:

void triNorm(float triNormx[3], float triNormy[3], float triNormz[3]) {
float normCrossx;
float normCrossy;
float normCrossz;

float normDx;
float normDy;
float normDz;
float distance;

normCrossx = (triNormx[0] - triNormx[1]) * (triNormx[1] - triNormx[2]);
normCrossy = (triNormy[0] - triNormy[1]) * (triNormy[1] - triNormy[2]);
normCrossz = (triNormz[0] - triNormz[1]) * (triNormz[1] - triNormz[2]);

distance = sqrt(normCrossx * normCrossx + normCrossy * normCrossy + normCrossz * normCrossz);

normDx = normCrossx / distance;
normDy = normCrossy / distance;
normDz = normCrossz / distance;

glNormal3f(normDx, normDy, normDz);
}

void geTri1VertNorm3f(float vertx1, float verty1, float vertz1) {
triNorm( vertx1, verty1, vertz1);
glVertex3f( vertx1, verty1, vertz1);
}

void geTri2VertNorm3f(float vertx2, float verty2, float vertz2) {
triNorm( vertx2, verty2, vertz2);
glVertex3f( vertx2, verty2, vertz2);
}

void geTri3VertNorm3f(float vertx3, float verty3, float vertz3) {
triNorm( vertx3, verty3, vertz3);
glVertex3f( vertx3, verty3, vertz3);
}

Thanks,
Iceman

in all of these, p1, p3, and p3 are the three verticies of the triangle. [0] is the x componant, [1] is the y componant, and [2] is the z componant.


Not sure what that last bit of code was for, but if you want something to draw a single flat-shaded triangle (this assumes glBegin(GL_TRIANGLES) has been called allready)

Thanks. I was trying to make something like your "void DrawTri(float p1[3], float p2[3], float p3[3])", but I wasn't sure how to go about programming it. Obviously "void geTri1VertNorm3f(float vertx1, float verty1, float vertz1)" was not the answer.

Thanks,
Iceman

Hmm it's still not working. here's the part that I think is the problem:
then I write the verticies in like this:
I get an incompatible type error when I try to build this. What am I doing wrong?

Thanks,
Iceman

geTriVertNormal3f wants three arrays of floats with three elements each. You are trying to pass it three floating point numbers instead.

Ok I figured it out. Sorry for all the confusion my coding needs to get better .

Thanks,
Iceman

That won't do what you want. Averaging the vertex coordinates does not give you a normal vector. If you need a version that takes scalar arguments, heres my code with scalar arguments:

use the CalcFaceNorm I posted above.

Wow that looks a lot smoother. Thanks .

Iceman