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Scale, translate
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Translate scale
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Rotate, Translate
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Translate, Rotate

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Line (A,B) , A=(0,0,0) B=(1,0,0)
S=(2,2,1)
T=(2,3,0)
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First Scale, then Translate
A’=(0,0,0) B’=(2,0,0); A’’=(2,3,0); B’’=(4,3,0)
First Translate, then Scale
A’=(2,3,0) B’=(3,3,0); A’’=(4,6,0); B’’=(6,6,0)

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Assume drawHouse( ) draws house #1
How can we draw house #2
Rotate first or translate first?
Rotate first
How can we draw both?
DrawHouse( ); glTranslate..
glRotate…
DrawHouse( );

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House 1
House1 M2 - House2
House1 M3 - House3

 glPushMatrix( )
 glPopMatrix( )

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 drawHouse( ); glPushMatrix( ); //remember the matrix for
//drawing house 1
…//Apply m2; drawHouse( ); //draw house2 glPopMatrix( ); //pop the matrix for house 1
…//Apply m3; drawHouse( ); //draw house 3;

for(int i = 0; i < 12; i++){ glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslated(320,240,0); glRotated(i*30, 0,0,1); glTranslated(0, radius , 0); drawPolyLineFile("dino.dat1");
}
Correct?

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//first glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslated(320,240,0); glTranslated(radius,0 , 0); drawPolyLineFile("dino.dat1");
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//second glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslated(320,240,0); glRotated(36,0,0,1); glTranslated(radius, 0 , 0); drawPolyLineFile("dino.dat1");

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 for(int i = 0; i < 12; i++){ glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslated(320,240,0); glRotated(i*30, 0,0,1); glTranslated(0, radius , 0);
 drawPolyLineFile("dino.dat1");
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}

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The Ring Again: Make Use of Matrix
Stack
//method 2
//use push and pop glMatrixMode(GL_MODELVIEW); glLoadIdentity();
} for(int i = 0; i < 10; i++){ glPushMatrix(); glTranslated(320,240,0); glRotated(i*36, 0,0,1); glTranslated(0, radius , 0); drawPolyLineFile("dino.dat1"); glPopMatrix();

Transformations can be thought of as a change in coordinate system
 if we specify a sequence of transformations always in terms of a fixed (world) coordinate system, they should be ordered from right-toleft.
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But if we think of all transformations in terms of a local (object) coordinate system, they should be ordered from left-to-right.

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 glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslated(320,240,0); glTranslated(radius,0 , 0); drawPolyLineFile("dino.dat1");
//from first to second, read it with coordinate transformation
 glTranslated(-radius,0 , 0);
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 glRotated(36, 0,0,1); glTranslated(radius,0 , 0); drawPolyLineFile("dino.dat1");

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The Ring Again: Understand it with
Coordinate Transformation
//method 3, use relative transformation glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslated(320,240,0); glTranslated(radius,0 , 0); drawPolyLineFile("dino.dat1");
//draw the rest 9 for(int i=0; i < 9; i++)
{ glTranslated(-radius,0 , 0); glRotated(36, 0,0,1); glTranslated(radius,0 , 0); drawPolyLineFile("dino.dat1");
}

How to get this with both translation and rotation?

for (int count = 0; count <6; count++)…..//draw a snow flake
{ flakeMotif(); glScalef(1.0,-1.0,1.0);.//reflection, using scale (1,-1,1) flakeMotif(); glScalef(1,-1,1);.// glScalef(1.0,-1.0,1.0);.//reflect back glRotate(60,0,0,1);
}

While (!bored)
{ drawSnowFlakes();
….//moving to a new spot
}

for(<some number of iterations>)
{ forward(length,1); // draw a line in the current direction turn(angle); // turn through angle degrees length += increment; // increment the line length
}