I have a perspective FOV, but when rotating, it doesn't "look" correct - Farther objects traverse faster than closer objects, passing them in the middle of the screen.
So: Is this correct? Using right-handed coordinates, if that matters?
public static Matrix4x4 PerspectiveFOV(float fov, float aspect, float near, float far)
{
float yScale = 1.0F / (float)Math.Tan(fov / 2);
float xScale = yScale / aspect;
float farmnear = far - near;
return new Matrix4x4(
xScale, 0, 0, 0,
0, yScale, 0, 0,
0, 0, far / (farmnear), 1,
0, 0, -near * (far / (farmnear)), 1
);
}
Thanks.
I see a couple of problems. First, the argument to tan() should be converted from degrees to radians.
Second, the formula for perspective projection in OpenGL is a little different from yours. As specified here, it uses 'near - far' in the denominator instead of your 'far - near'. The numerator terms are also different. Modifying your function slightly and converting from Java to C, I produced a projection matrix identical to the one given by gluPerspective() with the following:
static void my_PerspectiveFOV(double fov, double aspect, double near, double far, double* mret) { double D2R = M_PI / 180.0; double yScale = 1.0 / tan(D2R * fov / 2); double xScale = yScale / aspect; double nearmfar = near - far; double m[] = { xScale, 0, 0, 0, 0, yScale, 0, 0, 0, 0, (far + near) / nearmfar, -1, 0, 0, 2*far*near / nearmfar, 0 }; geom_matrix4_copy(m, mret); }