CODEWITHSUNDEEP
c#opengl
Christoph
Christoph

Reputation: 542

gl.begin() after gl.end() -> rendering is black

I'm trying to render different primities in the same context. When I Do

        OpenGL gl = GlControl.OpenGL;
        gl.Clear(OpenGL.GL_COLOR_BUFFER_BIT | openGL.GL_DEPTH_BUFFER_BIT);
        gl.LoadIdentity();

        gl.Begin(OpenGL.GL_LINES);

        gl.Color(1.0f, 0.0f, 0.0f);
        gl.Vertex(0.0f, 1.0f, 0.0f);
        gl.Color(0.0f, 1.0f, 0.0f);
        gl.Vertex(-1.0f, -1.0f, 1.0f);
        gl.End();

Everything is fine. But when I do

        OpenGL gl = GlControl.OpenGL;            
        gl.Clear(OpenGL.GL_COLOR_BUFFER_BIT | openGL.GL_DEPTH_BUFFER_BIT);
        gl.LoadIdentity();

        gl.Begin(OpenGL.GL_LINES);

        gl.Color(1.0f, 0.0f, 0.0f);
        gl.Vertex(0.0f, 1.0f, 0.0f);
        gl.Color(0.0f, 1.0f, 0.0f);
        gl.Vertex(-1.0f, -1.0f, 1.0f);
        gl.End();

        gl.Begin(OpenGL.GL_POINT);
        gl.Color(1.0f, 0, 0);
        gl.Vertex(0.0f, 0.0f, 1.0f);        
        gl.End();

I don't see anything anymore...

Upvotes: 1

Views: 272

Answers (2)

BDL
BDL

Reputation: 22177

GL_POINT is not allowed as argument to gl.Begin and should through a GL_INVALID_ENUM. If you want to draw points, the correct code would be

 gl.Begin(OpenGL.GL_POINTS);
                         ^

You should definitely check the return value of glGetError().

Upvotes: 3

datenwolf
datenwolf

Reputation: 162317

The valid tokens for immediate mode glBegin (which you should not use BTW) does not contain GL_POINT. You probably meant GL_POINTS. Using an invalid token causes an OpenGL error which may trip your particular C# bindings.

Upvotes: 4

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