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rotating matrix

Started by teslaa66 Oct 11, 2008 at 6:35 AM 1 reply 700+ views

Original Post

Oct 11, 2008 at 6:35 AM

Is there a way i can make a matrix


float newMatrix[16];

apply a rotation of 10 degrees on the X axis and 60 degrees on the Z axis but simulataneously so it doesnt rotate an already rotated matrix? then load the matrix before a model in my scene


glLoadMatrixf(newMatrix);

So now i can perform two rotations without one rotation rotating an already rotated scene? If this is all possible how do i apply a rotation of 10 degrees on the X axis and 60 degrees on the Z axis of a matrix please?

Graz

Oct 11, 2008 at 7:23 AM

See this page. About half way down, there's an explanation of how to create a 4x4 matrix representing compound rotations.

However, unless you really need this matrix for some reason, I'd suggest using glLoadIdentity and glRotatef to build the matrix on-the-fly. It will produce the same result as calling glLoadMatrix but will make your code a little easier to read.

Also, if you want to transform already positioned objects, try using glMultMatrix or omitting glLoadIdentity.

teslaa66

Author

teslaa66

Oct 11, 2008 at 8:19 AM

probably be easier if i show u my display

  glLoadMatrixf(carMatrix); //Loads Car Matrix  glTranslatef(0,0,9.03+carHeight); //Translates the car to the correct height  glScalef(0.035,0.025,0.023); //Scales the car to the right side  glBindTexture(GL_TEXTURE_2D, texture[5]); //Textures the car  glRotatef(carRoll, 1, 0, 0); //Rolls the car  glRotatef(carPitch, 0, 1, 0); //Effects the pitch of the car  rendermd2(car); //Renders the car

Here if i effect the roll of the car then applying the pitch doesnt pitch the car it pitches the already rolled car.

If i apply a glLoadIdentity after the first rotate then the car loses the scale and translate as well as the first rotate. Any ideas?

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