plib-users

[Plib-users] Grrr.... I only get a black screen

[Peter P. <pet...@st...>]

I have been playing around with wxWindow and ssg and I simply cannot get it 
working properly.

My program can be found here: http://rafb.net/paste/results/TcxCwP78.html 
It shows to windows. One is drawn using ssg and _should_ show a white 
rectangle, but only shows a black screen. The other window is drawn using 
direct opengl calls, and shows (and should show) a spinning red rectangle.

It can be compiled with this command:
g++ wxssg.cc -o wxssg `wx-config --cxxflags --libs --gl-libs` -lplibssg 
-lplibul -lplibsg

Can anybody explain to me why only the red rectangle works?

PS. considering that it works with direct opengl calls, I don't think the 
problem is in wxWindow.

-- 
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

R: [Plib-users] Grrr.... I only get a black screen

[Paolo L. <p.l...@ci...>]

Peter,

try these:

1. disable lighting (state->disable(GL_LIGHTING));
2. add the fourth vertex color (just three colors set for four
vertices), or just add a single color, single normal (flat shading);
3. move the sgSetCoord/setCamera to the draw() section and use rotate_
as azimuth (4th param in sgSetCoord) in order to look around.

Alternatively try loading a 3D model (get whatever 3DS model in
internet) instead of creating the leaf internally.

Let's hope and see...

Paolo


> -----Messaggio originale-----
> Da: pli...@li...=20
> [mailto:pli...@li...] Per conto di=20
> Peter Poulsen
> Inviato: gioved=EC 26 agosto 2004 10.09
> A: pli...@li...
> Oggetto: [Plib-users] Grrr.... I only get a black screen
>=20
>=20
> I have been playing around with wxWindow and ssg and I simply=20
> cannot get it=20
> working properly.
>=20
> My program can be found here:=20
> http://rafb.net/paste/results/TcxCwP78.html=20
> It shows to=20
> windows. One is drawn using ssg and _should_ show a white=20
> rectangle, but only shows a black screen. The other window is=20
> drawn using=20
> direct opengl calls, and shows (and should show) a spinning=20
> red rectangle.
>=20
> It can be compiled with this command:
> g++ wxssg.cc -o wxssg `wx-config --cxxflags --libs --gl-libs`=20
> -lplibssg
> -lplibul -lplibsg
>=20
> Can anybody explain to me why only the red rectangle works?
>=20
> PS. considering that it works with direct opengl calls, I=20
> don't think the=20
> problem is in wxWindow.
>=20
> --=20
> A: Because it messes up the order in which people normally read text.
> Q: Why is it such a bad thing?
> A: Top-posting.
> Q: What is the most annoying thing on usenet and in e-mail?
>=20
>=20
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>=20

Re: R: [Plib-users] Grrr.... I only get a black screen

[Peter P. <pet...@st...>]

Paolo Leoncini wrote:
> Peter,
> 
> try these:
> 
> 1. disable lighting (state->disable(GL_LIGHTING));
> 2. add the fourth vertex color (just three colors set for four
> vertices), or just add a single color, single normal (flat shading);
> 3. move the sgSetCoord/setCamera to the draw() section and use rotate_
> as azimuth (4th param in sgSetCoord) in order to look around.
> 
> Alternatively try loading a 3D model (get whatever 3DS model in
> internet) instead of creating the leaf internally.
> 
> Let's hope and see...
> 
> Paolo
> 
> 
> 
>>-----Messaggio originale-----
>>Da: pli...@li... 
>>[mailto:pli...@li...] Per conto di 
>>Peter Poulsen
>>Inviato: giovedì 26 agosto 2004 10.09
>>A: pli...@li...
>>Oggetto: [Plib-users] Grrr.... I only get a black screen
>>
>>
>>I have been playing around with wxWindow and ssg and I simply 
>>cannot get it 
>>working properly.
>>
>>My program can be found here: 
>>http://rafb.net/paste/results/TcxCwP78.html 
>>It shows to 
>>windows. One is drawn using ssg and _should_ show a white 
>>rectangle, but only shows a black screen. The other window is 
>>drawn using 
>>direct opengl calls, and shows (and should show) a spinning 
>>red rectangle.
>>
>>It can be compiled with this command:
>>g++ wxssg.cc -o wxssg `wx-config --cxxflags --libs --gl-libs` 
>>-lplibssg
>>-lplibul -lplibsg
>>
>>Can anybody explain to me why only the red rectangle works?
>>
>>PS. considering that it works with direct opengl calls, I 
>>don't think the 
>>problem is in wxWindow.
>>
Thanks alot! I finally got it working. I'm posting it here just for the 
archive.


#include <iostream>
#include <string>
#include <cassert>
#include <cmath>

#include <wx/wx.h>
#include <wx/glcanvas.h>
#include <wx/notebook.h>

#include <plib/ssg.h>

bool ssg_init = false;

class GL_Window : public wxGLCanvas
{
public:
	GL_Window(float c, wxWindow* parent, wxWindowID id, const wxPoint& pos, 
const wxSize& size,
			  long style=0, const wxString& name="GLCanvas", int* attribList = 0,
			  const wxPalette& palette = wxNullPalette)
		: wxGLCanvas(parent, id, pos, size, style, name, attribList, palette), 
c_(c), rotate_(c)
		{
		}
	virtual ~GL_Window() {}

	void init(int color) {
		SetCurrent();
		if(!ssg_init) {
			ssgInit();
			ssg_init = true;
		}
		ssgGetCurrentContext()->setNearFar(0.1, 10000.0);
		ssgGetCurrentContext()->setCullface(false);
			
		sgVec3 sunposn ;
		sgSetVec3(sunposn, 0.0f, -10.0f, 0.0f) ;
		ssgGetLight(0)->setPosition(sunposn) ;

		root_ = new ssgRoot;
		ssgVertexArray* vertices = new ssgVertexArray;
		sgVec3 x = { -0.5, 0.0f, -0.5 };
		sgVec3 y = { -0.5, 0.0f, 0.5 };
		sgVec3 z = { 0.5, 0.0f, 0.5 };
		sgVec3 w = { 0.5, 0.0f, -0.5 };
		
		vertices->add(z);
		vertices->add(y);
		vertices->add(x);
		vertices->add(w);

		sgVec4 white = { 1.0f, color, color, 1.0f};
		ssgColourArray* colours = new ssgColourArray;
		colours->add(white);
		ssgNormalArray* normals = new ssgNormalArray;
		sgVec3 normal = { 0, -1.0f, 0 };
		normals->add(normal);

		ssgVtxTable* n = new ssgVtxTable(GL_QUADS, vertices, normals, NULL, colours);
		ssgSimpleState* state = new ssgSimpleState () ;
		state->disable(GL_TEXTURE_2D);
		state->disable(GL_COLOR_MATERIAL);
		state->disable(GL_LIGHTING);
		n->setState(state);
		n->setCullFace(false);

		root_->addKid(n);
	}
	
	void draw() {
		rotate_ += 0.01;

		glClearColor(0.0, 0.0, 0.0, 0.0);
		glClear(GL_COLOR_BUFFER_BIT);

		SetCurrent();
		glViewport(0, 0, (GLint)200, (GLint)200);
		if(root_) {
			sgCoord coord;
			sgSetCoord(&coord, 0.0f, -2.0f, 0.0f, 5*cos(rotate_), 0.0f, 0.0f);
			ssgGetCurrentContext()->setCamera(&coord);
			ssgCullAndDraw(root_);
		}
		SwapBuffers();
	}

	void OnIdle(wxIdleEvent& event)	{
		draw();
		event.RequestMore();
	}
private:
	float c_;
	float rotate_;
	ssgRoot* root_;
	
	DECLARE_EVENT_TABLE();
};

class MyApp: public wxApp
{
	virtual bool OnInit();
};

IMPLEMENT_APP(MyApp)

bool MyApp::OnInit()
{
	wxFrame* frame = new wxFrame((wxFrame *)NULL, -1,  "Hello GL World",
								 wxPoint(50,50), wxSize(450,340) );
	frame->Show(TRUE);
	wxNotebook* book = new wxNotebook(frame, -1, wxPoint(-1,-1), wxSize(450,340));

	GL_Window* MyGLCanvas = new GL_Window(1, book, -1, wxPoint(-1,-1),
										  wxSize(200,200), wxSUNKEN_BORDER, "some text");
	book->AddPage(MyGLCanvas, "One");
	MyGLCanvas->init(1);
	
	MyGLCanvas = new GL_Window(0, book, -1, wxPoint(-1,-1),
							   wxSize(200,200), wxSUNKEN_BORDER, "some text");
	book->AddPage(MyGLCanvas, "Two");
	MyGLCanvas->init(0);
	return TRUE;
}

BEGIN_EVENT_TABLE(GL_Window, wxGLCanvas)
     EVT_IDLE(GL_Window::OnIdle)
END_EVENT_TABLE()


-- 
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

R: R: [Plib-users] Grrr.... I only get a black screen

[Paolo L. <p.l...@ci...>]

Peter Poulsen wrote:

> Thanks alot! I finally got it working.

Nice to have you on board!

Perhaps the problem was in the lighting. The quad normal is in the same
direction as the light (y-), so enabling lighting produces a black color
over black background. As counterproof try setting the clear color to
non black, re-enable lighting and see if the quad appears black.
Furthermore remember that SSG coordinate system is z-up (x-right,
y-into-the-screen) whilst OpenGL is y-up, so keep it into account when
setting light and camera positions in the world.

Greetings -

Paolo

Re: R: R: [Plib-users] Grrr.... I only get a black screen

[Peter P. <pet...@st...>]

Paolo Leoncini wrote:
> Peter Poulsen wrote:
> 
> 
>>Thanks alot! I finally got it working.
> 
> 
> Nice to have you on board!
> 
> Perhaps the problem was in the lighting. The quad normal is in the same
> direction as the light (y-), so enabling lighting produces a black color
> over black background. As counterproof try setting the clear color to
> non black, re-enable lighting and see if the quad appears black.
> Furthermore remember that SSG coordinate system is z-up (x-right,
> y-into-the-screen) whilst OpenGL is y-up, so keep it into account when
> setting light and camera positions in the world.
> 
> Greetings -
> 

I tried re-enabling light and set the clear color to blue. It turn out that 
it wasn't that, but I tried playing a little with the glViewport command, 
it definitely has something to do with it. As it is placed in my previous 
mail, it works fine.


-- 
A: Because it messes up the order in which people normally read text.
Q: Why is it such a bad thing?
A: Top-posting.
Q: What is the most annoying thing on usenet and in e-mail?

Re: R: [Plib-users] Grrr.... I only get a black screen

[Steve B. <sjb...@ai...>]

>>It shows to 
>>windows. One is drawn using ssg and _should_ show a white 
>>rectangle, but only shows a black screen. The other window is 
>>drawn using 
>>direct opengl calls, and shows (and should show) a spinning 
>>red rectangle.

I'm betting that the OpenGL rendering context isn't being
correctly set to the second window...but it's hard to know
without playing with the code.

---------------------------- Steve Baker -------------------------
HomeEmail: <sjb...@ai...>    WorkEmail: <sj...@li...>
HomePage : http://www.sjbaker.org
Projects : http://plib.sf.net    http://tuxaqfh.sf.net
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