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Thread: Rotating quad around itself but move it to a specific position of another quad

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  1. #1
    Newbie Newbie
    Join Date
    Jul 2013

    Rotating quad around itself but move it to a specific position of another quad

    i have the following problem: i have following setup:

    The red quad should always keep the position relative to the white quad. I got this working by using the same translation and rotation matrix as the white quad.
    The red one "recieves" the matrices from the white one.

    img at: (would have used IMG tag, but was denied )

    Now i want to rotate the red quad around itself. I do it, by adding the amout of degree to the one recieved from the parent object and using it as the values for the rotation matrix:

    Code :
    cos(deg+turnDeg), -sin(deg+turnDeg), 0.0, 0.0
    sin(deg+turnDeg),  cos(deg+turnDeg), 0.0, 0.0
                 0.0,               0.0, 1.0, 0.0
                 0.0,               0.0, 0.0, 1.0

    deg: the amout the white quad is rotated
    turnDeg: the amount the red quad should be rotated

    The problem now is, that if i let it rotate, it starts rotating around the center of the white quad.

    I now have the question, how i can rotate it around itself but let it stay at the position relative to the white quad?

    Source of the VertexShader:
    Code :
    #version 150 core
    in vec4 in_Position;
    in vec4 in_Color;
    in vec2 in_TextureCoord;
    uniform mat4 window_Matrix;
    uniform mat4 ikarus_Rotation_Matrix;
    uniform mat4 translation_Matrix;
    uniform mat4 ntranslation_Matrix;
    out vec4 pass_Color;
    out vec2 pass_TextureCoord;
    void main(void) {
    	gl_Position = window_Matrix * translation_Matrix * ikarus_Rotation_Matrix *  in_Position;
    	pass_TextureCoord = in_TextureCoord;
    	pass_Color = in_Color;

    Last edited by CDGJosh; 07-02-2013 at 03:32 PM.

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