Question

I wonder if anyone can help me learn how to correctly use glMultMatrix.

I have the following render code in my app, however it appears I cannot just feed a C struct with the matrix to glMultMatrix :

-(void)render
{

matrixStruct matrices[] = {1, 0, -0, -9.37988, 0, -0.651537, 0.758617, 1133.64, 0, 0.758617, 0.651537, 129730, 0, 0, 0, 1};


// clear the matrix
glPushMatrix();
glLoadIdentity();

//scale
glScalef(0.00001, 0.00001, 0.00001);

    glMultMatrixf(matrices);

[mesh render];

//restore the matrix
glPopMatrix();
}

I understand from the documentation at http://www.opengl.org/sdk/docs/man/xhtml/glMultMatrix.xml that I need to provide :

void glMultMatrixd( const GLdouble *    m);
void glMultMatrixf( const GLfloat *     m);

m
Points to 16 consecutive values that are used as the elements of a 4 × 4 column-major        matrix.

I am not sure how I should format my matrix and pass it to glMultMatrix. Also do I need to enable glMatrixMode before I call render ?

Thank you

Answer 1

Worked it out – I needed to pass an array of floats :

e.g

float matrices[] ={1,0,0,0,0,1,0,0,0,0,1,0,-578.556,7068.92,48.6953,1};

All working now – thanks.