texture, background delete

Graphics and GPU Programming Programming

Started by tomsh December 21, 2011 07:46 AM

7 comments, last by tomsh 12 years, 4 months ago

Author

December 21, 2011 07:46 AM

Hey.

I tried to delete the background of texture,



		glEnable (GL_BLEND);

		glColor4f(1.0f,1.0f,1.0f,1.0f);

		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);



		glBegin(GL_QUADS);				//draw...

			glTexCoord2d(1.0f,1.0f);glVertex3f( xP, yP2,  0);

			glTexCoord2d(0.0f,1.0f);glVertex3f( xP2, yP2, 0);

			glTexCoord2d(0.0f,0.0f);glVertex3f( xP2, yP, 0);

			glTexCoord2d(1.0f,0.0f);glVertex3f( xP, yP,  0);

		glEnd();

So it deleted it... but it draws other background inplace...
It draw the glClearColor
glClearColor(0.f, 1.f, 0.f, 0.1f);

but I want it [font=Arial,]transparent.[/font]
[font=Arial,]
[/font]
[font=Arial,]

[/font]
[font=Arial,]You see the green background they have?[/font]

[font="Arial,"][size=2]
[/font]

FXACE

183

December 21, 2011 07:59 AM

Hey.

I tried to delete the background of texture,

glEnable (GL_BLEND); glColor4f(1.0f,1.0f,1.0f,1.0f); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glBegin(GL_QUADS); //draw... glTexCoord2d(1.0f,1.0f);glVertex3f( xP, yP2, 0); glTexCoord2d(0.0f,1.0f);glVertex3f( xP2, yP2, 0); glTexCoord2d(0.0f,0.0f);glVertex3f( xP2, yP, 0); glTexCoord2d(1.0f,0.0f);glVertex3f( xP, yP, 0); glEnd();

So it deleted it... but it draws other background inplace...
It draw the glClearColor
glClearColor(0.f, 1.f, 0.f, 0.1f);

but I want it [font="Arial,"]transparent.[/font]
[font="Arial,"]
[/font]
[font="Arial,"]
[/font]
[font="Arial,"]You see the green background they have?[/font]
[font="Arial,"] [/font]

Are your game-play objects use 32-bit textures? Looks like they haven't alpha channels...

tomsh

Author

December 21, 2011 08:09 AM

I think I didn't understand what you said.
the textures are png, I loaded them with sfml.

texture[fNum].LoadFromFile(fName)

FXACE

183

December 21, 2011 08:38 AM

I think I didn't understand what you said.
the textures are png, I loaded them with sfml.

texture[fNum].LoadFromFile(fName)

Did you checked alpha (mask) channels of them? (Better if you would upload this texture).

tomsh

Author

December 21, 2011 08:44 AM

this is the picture

FXACE

183

December 21, 2011 08:57 AM

this is the picture

Texture is set correct (it contains mask channel which have visible and invisible (intensity) pixels).

OpenGL code which you putted in is correct too (for transparent effect).

I think bug is in another place.

Just a warning message: you calling glTexCoord2d (which expects parameters of type "double") when you put there "float" ("1.0f -> 1.0").

tomsh

Author

December 21, 2011 09:18 AM

thanks a lot about the help.
here the full code of the draw.

if(ySpeed != 0 || xSpeed != 0)

				deg = fmod(atan2(yP-(yP+ySpeed),xP-(xP+xSpeed))/3.14159265f*180.f,360.f);

			glMatrixMode(GL_TEXTURE);

			glLoadIdentity();

			glPushMatrix();

			glTranslatef(0.5f, 0.5f, 0.f);

			glRotatef(deg, 0.f, 0.f, 1.f);

			glTranslatef(-0.5f,-0.5f, 0.f);

			glMatrixMode(GL_MODELVIEW); 







		glEnable (GL_BLEND);

		glColor4f(1.0f,1.0f,1.0f,1.0f);

		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);



		glBegin(GL_QUADS);				//draw...

			glTexCoord2d(1.0,1.0);glVertex3f( xP, yP2,  0);

			glTexCoord2d(0.0,1.0);glVertex3f( xP2, yP2, 0);

			glTexCoord2d(0.0,0.0);glVertex3f( xP2, yP, 0);

			glTexCoord2d(1.0,0.0);glVertex3f( xP, yP,  0);

		glEnd();





		glMatrixMode(GL_TEXTURE);

		glPopMatrix();



		glMatrixMode(GL_MODELVIEW); 

		glDisable (GL_BLEND);	}

init func of opengl:

	glClearDepth(1.f);

    glClearColor(0.f, 1.f, 1.f, 0.f);

    glEnable(GL_DEPTH_TEST);

    glDepthMask(GL_TRUE);

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    gluPerspective(90.f, 1.f, 1.f, 500.f);

	GlTextLoad("pic.png", 0);			//load picture...

	GlTextLoad("Menu1.png", 1);

	GlTextLoad("Menu2.png", 2);

	GlTextLoad("Menu3.png", 3);

	GlTextLoad("pic1.png", 4);

	GlTextLoad("pic2.png", 5);

	GlTextLoad("Back.png", 6);

	glEnable(GL_TEXTURE_2D);

gltexload func: (load texture with sfml)

bool WinS::GlTextLoad(char* fName, int fNum)

{





	if(!texture[fNum].LoadFromFile(fName))

	{

		MessageBox(NULL, "Can't load the texture...", "Eror", MB_OK);

		Running = false;



		return false;

	}



	texture[fNum].CreateMaskFromColor(sf::Color(1, 1, 1 , 0));

	return true;

}

resize opengl

glViewport(0, 0, width, height);

    glMatrixMode(GL_PROJECTION);

    glLoadIdentity();

    gluPerspective(90.0f, float(width) / float(height), 1.0f, 500.0f);

    glMatrixMode(GL_MODELVIEW);

    glLoadIdentity();

This is in the start of the render func:

	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

    glMatrixMode(GL_MODELVIEW);

I don't think there is more relevant code...

FXACE

183

December 21, 2011 10:02 AM

texture[fNum].CreateMaskFromColor(sf::Color(1, 1, 1 , 0));

I think this operation overwrites image's mask channel. Why to do this if your image already has a mask? (P.S. Just currently looked at SFML documentation)

tomsh

Author

December 21, 2011 10:05 AM

I added it just now, for check if it will do something, and forgot to delete it.
Without that it still happen.

I found what the problem.
SFML load the texture as 8 bit...

texture, background delete

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