Computer Graphics

Computer Graphics
Transformation & Animation

Transformations

(1, 2)

(1, 2) (2, 2)

(2, 3)
(1, 2) (2, 2)

(1, 3) (2, 3)
(1, 2) (2, 2)

16 Points!!

Cube
drawCube();

drawCube();
// Move right 2 squares
Cube

drawCube();
// Move right 2 squares
drawCube();
Cube
Cube

Cube
Cube

Cube
Cube
Cube

Cube
Cube
Cube

Cube
Cube
Cube
Cube

Same cube
Different origin
Cube
Cube
Cube
Cube

Transformations: Types

T
glTranslatef(x, y, z);
Types: Translation

R
glRotatef(angle, x, y, z);
Types: Rotation

S
glScalef(x, y, z);
Types: Scale

Transformations: Matrix Stacks

MV =
I
Matrix Stacks: Model View

MV = I C ube
Matrix Stacks: Model View

MV = I C ube
T
Matrix Stacks: Model View

MV = I C ube
T
C ube
Matrix Stacks: Model View

MV = I C ube
T
T
C ube
Matrix Stacks: Model View

MV = I C ube
T
T
R
C ube
Matrix Stacks: Model View

MV = I C ube
T
C ube
T R C ube
Matrix Stacks: Model View

Making a mess

Need a way to reset
Cube
Cube
Cube
Cube

glPushMatrix();
drawCube();
Cube

glPushMatrix();
// Draw Cubes
Cube

glPushMatrix();
// Draw Cubes
Cube
Cube

glPushMatrix();
// Draw Cubes
Cube
Cube

glPushMatrix();
// Draw Cubes
Cube
Cube
Cube

glPushMatrix();
// Draw Cubes
Cube
Cube
Cube

glPushMatrix();
// Draw Cubes
Cube
Cube
Cube
Cube

glPushMatrix();
// Draw Cubes
glPopMatrix();
Cube
Cube
Cube
Cube

No unsightly transforms

Transformations: Matrix Stacks

Pro =
I
Matrix Stacks: Projection

Pro = I 2D
gluOrtho2D(…);
y
(0,0)
x
Matrix Stacks: Projection

Pro = I 3D
gluOrtho3D(…);
y
(0,0,0)
x
Matrix Stacks: Projection

Pro = I Per
gluPerspective(…);
y
(0,0,0)
x
Matrix Stacks: Projection

Now Loading
Projection

Animation

T=0 T=1 T=2 T=3 T=4
Animation

glutTimerFunc(…);
T=0 T=1 T=2 T=3 T=4
Animation

Now Loading
Rotating Cube

Animation: User Input

User Input: Keyboard
glutKeyboardFunc(…);

void Render::keyPos(unsigned char key, int x, int y)
{
switch (key)
{
case 'r': // Reverse rota=on
// Reverse the rota=on of the planets … (Code here)
break;
case 'p': // Pause rota=on
// Pause the rota=on of the planets … (Code here)
break;
case 13: // 'Enter' Key
showTitle = false;
reshape(Wx, Wy); // Force a reshape so that the new projec=on matrix is loaded
break;
case 27: // 'Esc' key on the keyboard. Quit the program when the esc key is pressed
exit (0);
break;
default: // Unknown key ... do nothing
break;
}
}

glutMouseFunc(…);
glutMotionFunc(…);
User Input: Mouse

OpenGL
2D
y
(0,0)
(Wx,Wy)
x
3D
z
y
(0,0,0)
x
User Input: Mouse

OpenGL
Mouse
y
(Wx,Wy)
2D
(0,0)
x
(0,0)
x
3D
y
x
y
(Wx,Wy)
z
(0,0,0)
User Input: Mouse

void Render::mouseClick(int buVon, int state, int x, int y){
if (state == GLUT_DOWN)
{
mOldX = x;
mOldY = y;
switch (buVon)
{
case GLUT_LEFT_BUTTON:
mBuVon = LEFT;
break;
case GLUT_MIDDLE_BUTTON:
mBuVon = MIDDLE;
break;
case GLUT_RIGHT_BUTTON:
mBuVon = RIGHT;
break;
default:
// Unknown buVon … skip it
break;
}
}
else if (state == GLUT_UP) // If this is the release then reset the buVon
{
mBuVon = -­‐1;
}}

void Render::mouseMove(int x, int y){
if (mBuVon == LEFT)
{
rot[0] -­‐= ((mOldY -­‐ y) * 180.0f) / 1000.0f;
rot[1] -­‐= ((mOldX -­‐ x) * 180.0f) / 1000.0f;
clamp(rot[0], rot[1], rot[2]);
}
else if (mBuVon == MIDDLE)
{
eye[2] -­‐= ((mOldY -­‐ y) * 180.0f) / 500.0f;
clamp(rot[0], rot[1], rot[2]);
}
else if (mBuVon == RIGHT)
{
eye[0] += ((mOldX -­‐ x) * 180.0f) / 1000.0f;
eye[1] -­‐= ((mOldY -­‐ y) * 180.0f) / 1000.0f;
clamp(rot[0], rot[1], rot[2]);
}
mOldX = x;
mOldY = y;
// I changed values to be used in the modelview matrix.
// Update my display and the objects on the screen
glutPostRedisplay();}

Whew……

Assignment

Project
• Talk to me about your idea: Today
• Give a short (1 slide) 3 min overview of
what you are doing: Thursday

Questions
Transformation & Animation

Templates

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