CODEWITHSUNDEEP
pythonopengl
matt
matt

Reputation: 1066

Drawing in OpenGL is always white

I'm trying to draw some simple triangles in OpenGL. The problem is that my triangle is always white, wheras I put some color with the glColor3f function:

def OnDraw(self):

    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT)
    glClearColor(.1, 0.1, 0.1, 1.0)

    glBegin (GL_TRIANGLES)
    glColor3f (1.0, 0.0, 0.0)
    glVertex2f (0.25, 0.25)
    glColor3f (0.0, 1.0, 0.0)
    glVertex2f (0.12, 0.25)
    glColor3f (0.0, 0.0, 1.0)
    glVertex2f (0.25, 0.4)
    glEnd()

and here is my initialization:

def InitGL(self):
    # set viewing projection
    glMatrixMode(GL_PROJECTION)
    glFrustum(-0.5, 0.5, -0.5, 0.5, 1.0, 3.0)

    # position viewer
    glMatrixMode(GL_MODELVIEW)
    glTranslatef(0.0, 0.0, -2.0)

    glEnable(GL_DEPTH_TEST)
    glEnable(GL_LIGHTING)
    glEnable(GL_LIGHT0)

Any idea?

Upvotes: 0

Views: 849

Answers (2)

matt
matt

Reputation: 1066

I solved the problem my removing: glEnable(GL_DEPTH_TEST) glEnable(GL_LIGHTING) glEnable(GL_LIGHT0)

Can somebody explained me why is it working now?

Upvotes: 0

datenwolf
datenwolf

Reputation: 162164

With lighting enabled vertex colors are no longer considered for the calculations. Instead you have to set material properties. However vertex colors are quite convenient so there's a method to use vertex colors to set material properties.

glEnable(GL_COLOR_MATERIAL);
glColorMaterial(GL_FRONT_AND_BACK, GL_AMBIENT_AND_DIFFUSE);

However note that for lighting to work you must provide vertex normals otherwise things will look strange. It might be best to disable lighting for the time being.

On a different note: Please stop using old and dusted immediate mode, fixed function pipeline OpenGL. Instead learn about modern OpenGL. I recommend http://arcsynthesis.org/gltut for a start.

Upvotes: 2

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