Testing the Colors

So here is the code. I will be using the RGBA mode. Each vertex of the triangle to be created will have different colors. The points where the colors intersect are of no concern as OpenGL takes care of that. For your information, it is the same one that was developed for testing the animation.

void Draw3D(SDL_Surface *S) // OpenGL drawing code here

{

glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

//clear screen and

//depth buffer. Screen color has been cleared

//at init

glRotatef(angle,0.0f,1.0f,0.0f);// Rotate The Triangle On The Y axis

glLoadIdentity(); // reset the modelview matrix

glBegin(GL_TRIANGLES);

glVertex3f( 0.0f, 1.0f, 0.0f);

glVertex3f(-1.0f,-1.0f, 0.0f); glVertex3f( 1.0f,-1.0f, 0.0f);

glEnd();

glFlush(); // flush the gl rendering pipelines

return;

}

So now I will be adding the color display code. Each vertex will have different colors -- red, blue and green.

void Draw3D(SDL_Surface *S) // OpenGL drawing code here

{

glClear (GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

//clear screen and

//depth buffer. Screen color has been cleared

//at init

glRotatef(angle,0.0f,1.0f,0.0f);// Rotate The Triangle On The Y axis

glLoadIdentity(); // reset the modelview matrix

glBegin(GL_TRIANGLES);

glColor3f(1.0f,0.0f,0.0f);//the vertex displayed after this

//statement would be red

glVertex3f( 0.0f, 1.0f, 0.0f);

glColor3f(0.0f,1.0f,0.0f);//the vertex displayed after this

//statement would be green

glVertex3f(-1.0f,-1.0f, 0.0f);

glColor3f(0.0f,0.0f,1.0f);//the vertex displayed after this

//statement would be blue

glVertex3f( 1.0f,-1.0f, 0.0f);

glEnd();

glFlush(); // flush the gl rendering pipelines

return;

}

That completes adding colors to our test application. It is simple when compared to what can be achieved using OpenGL. The aspects that this article doesn't discuss include dithering and smoothing of the rendered image. These aspects will be the focus of the next part of this series. Till next time...