ComputerGraphics-CEFET

This repository was dedicated to my works at Computer graphics class while doing my Bachelors in Computer Science in CEFET-RJ.

All programs here were written using OpenGL for Python.

Prologue

In the beginning of this class, I was doing a student exchange program in Germany, sponsored by the brazilian government. Thats why I needed to figure it out how to learn Computer graphics whitout the Professor's help. So I started learning from the very basics of this subject till something more complex.

Points.py

Nothing could be easier to create in Computer Graphics as some bunch of points on screen. But it was so easy to create that I connected those points with lines too. Creating a sort of "art" (at least for the "early me" on the past).

Teapot

Every OpenGL lib I had seen has a built-in function to create a wireframe from a teapot. I know, it is not that hard to implement that, but it was my first steps in that subject.

###Sendlinger Tor While my exchange program, I saw a really nice place in Munich. Its name is Sendlinger Tor, it is an old medieval gate at a square in Munich's city center. That was my inspiration to a nicer work with OpenGL.

The real Sendlinger tor

So I started coding its lines and found a real problem. I needed to find a perfect equation to reproduce the central arch.

	for x in arange(-1,1,0.01):
		y = -2*x**2 -1
		glVertex3f(x+3,y,-1)
	
	for x in arange(-1,1,0.01):
		y = -2*x**2 -1
		glVertex3f(x+3,y, 1)

But I wasn't happy with the result, I wanted more! I wanted to start giving it a appearance of a solid. In that time I wasn't reading about solids already, so I needed to improvise!

My first castle

So it was time to move on, learn something new and a bit more harder. I was going to deal with solids. In Germany I had the oportunity of visiting a lot of castles, and I was fascinated with it since ever! So why not building my own castle?

Making my job easier

Every castle needs walls and towers, mine too! But I was creating a really humble castle, so every tower and wall had the same size. Well it makes things easier! I just needed to calculate the tranposition of its coordinates.

• Creating Towers

  def criaTorre(x,z):
	torre = []
	for vertice in vertices:
		torre_vertice = []
		torreX = vertice[0] + x
		torreY = vertice[1]
		torreZ = vertice[2] + (z*-1) 

		torre_vertice.append(torreX)
		torre_vertice.append(torreY)
		torre_vertice.append(torreZ)

		torre.append(torre_vertice)
	return torre

def draw () :
	### Criando as Torres ###
	glBegin(GL_QUADS)
	z = 0
	for i in range(2):
		x = 0	
		for j in range(2):
			torre = criaTorre(x,z)
			glColor3fv((0.5,0.2,0.2))
			for face in faces:
				glNormal3fv(calculaNormalFace(face))
				for vertice in face:
					glVertex3fv(torre[vertice])
			x += 10
		z += 10
	glEnd()

• Creating walls

def criaMuro(x,z,horizontal):
	muro = []
	if not horizontal:
		for vertice in vertices_Muro:
			muro_vertice = []
			muroX = vertice[0] + x
			muroY = vertice[1]
			muroZ = vertice[2] + (z*-1)

			muro_vertice.append(muroX) 
			muro_vertice.append(muroY)
			muro_vertice.append(muroZ)

			muro.append(muro_vertice)
		return muro
	else:
		for vertice in vertices_Muro:
			muro_vertice = []
			muroX = vertice[2] + z
		
			muroY = vertice[1]
			muroZ = -vertice[0]

			muro_vertice.append(muroX) 
			muro_vertice.append(muroY)
			muro_vertice.append(muroZ)

			muro.append(muro_vertice)
		return muro

### Criando Muros ###
	glBegin(GL_QUADS)
	muro = criaMuro(0,10,False)
	for face in faces_muro:
		glNormal3fv(calculaNormalFace(face))
		for vertice in face:
			glVertex3fv(muro[vertice])
	z = 0
	
for i in range(2):
		muro = criaMuro(0,z,True)
		for face in faces_muro:
			glNormal3fv(calculaNormalFace(face))
			for vertice in face:
				glVertex3fv(muro[vertice])
		z += 10
	glEnd()

Let's put some colors on it and we are good to go!

Shine bright like a diamond!

As you can see, I had a solid big fancy castle! But the sun was not shining my kingdom! I needed light and learn how to reflect this light on my castle! That was time to learn about Normal and Light's behavior.

As you can see, there is some bug with my normal for the gate, but I was really ok with that.

Now was time to play around with camera, let's simulate that we are at the Castle's main gate!

End

That was how I learned the basics of Computer graphics in 3 weeks of study with PyOpenGL before reaching my country and University.

You can read my my full report (in Portuguese) here.