Introduction of OpenGL - Transformation

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Introduction of OpenGL- Transformation

• Luke Yulu Chen

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Review

• OpenGL Command Syntax

g l C o l o r 3 f ()
gl library
command
number of arguments
data type of arguments
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Review (2)

• Specifying Color
• glColor3f (float r, float g, float b)
• r, g, b are floating points from 0 to 1
• glColor3ub (int r, int g, int b)
• r, g, b are integers from 0 to 255

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Review (3)

• Specifying Vertices
• glVertex2f (float x, float y)
• 2D coordinates
• glVertex3f (float x, float y, float z)
• 3D coordinates
• Calls to glVertex( ) are only effective between
  a glBegin( ) and glEnd( ) pair.

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Review (3)

• OpenGL Geometric Drawing Primitives
• glBegin (primitives type)
• glVertex( )
• glEnd ( )
• Primitives Type
• GL_POINTS, GL_LINES, GL_POLYGON

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OpenGL Transformation

• Viewing Transformations
• change the position and orientation of the
  viewpoint
• Modeling Transformations
• transform objects by shifting, rotating and
  scaling them

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Modeling Transformation

• Translation
• Rotation
• Scaling

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Order of Transformation
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Transformation Commands (1)

• Translate
• glTranslatef (float x, float y, float z)
• ex. glTranslatef (50.0, 50.0, 0.0)

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Transformation Commands (2)

• Rotate
• glRotatef (float angle, float x, float y, float
  z)
• rotates an object in a counterclockwise direction
  about the vector from the origin through the
  point (x, y, z)
• ex. glRotatef (30.0, 0.0, 0.0, 1.0)

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Transformation Commands (3)

• Scale
• glScalef (float x, float y, float z)
• ex. glScalef (2.0, -0.5, 0.0)