DGL :: Thema anzeigen - glGetTexParameteriv

A PGLInt is a pointer to an GLInt....and a pointer has to point somewhere...

Code:

var w1,h1: GLint;

// ...

glGetTexParameteri( GL_TEXTURE_2D,GL_TEXTURE_WIDTH,@w1);
glGetTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_HEIGHT,@h1);

Note that glTexSubImage2D does require that the texture has already sufficient size. The size of a texture is initially zero! In contrast to that glTexImage2D does delete the texture buffer and create a new one with correct size.

glTexSubImage2D and glTexImage2D do read from main memory, not from another texture. If you want to copy a texture you might want to use a Framebuffer-Object and render a Fullscreen-Quad. That's faster because you don't have to download and upload the texture to graphics memory again.

ok i see what you mean...
Now i get this results from the w1 and h1
w1 = 0 my pic is 450 width
h1 = -1234354 my pic is 350 height

So you say that i must put the image to the memory and how can i call the image with glTexSubImage2D?

Zitat:

As already said, a framebuffer object is MUCH faster, since the bus between graphics card and main memory is relatively slow.

Zitat:

GLubyte* data = new GLubyte[w1*h1*4]; // dynamic array of type GLubyte and size w1*h1*4

Code:

GLubyte* data = new GLubyte[w1*h1*4]; // dynamic array of type GLubyte and size w1*h1*4

oops. an array is already a pointer. So in my code, there would be a pointer too much

this should be better:

Code:

var Data: array of GluByte;
begin
  //...
  SetLength(Data, w1*h1*4);
  //...
end;

Autor:	azrael11 [ Sa Dez 04, 2010 12:09 ]
Betreff des Beitrags:	glGetTexParameteriv
i try this Code: var w1,h1: PGLint; begin glTranslatef(x,y,z); glScalef(xScale,yScale,zScale); glRotatef(xAngle, 1, 0, 0); glRotatef(yAngle, 0, 1, 0); glRotatef(zAngle, 0, 0, 1); glBindTexture(GL_TEXTURE_2D, WhatTex); // Bind the Texture to the object glGetTexParameteri( GL_TEXTURE_2D,GL_TEXTURE_WIDTH,w1); glGetTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_HEIGHT,h1); glBindTexture(GL_TEXTURE_2D, texBox); // Bind new Texture to the object // now i want to use the glTexSubImage2D( ) //command so i copy then whattex in the tex box i have two problems First; gltexsubimage2d want integer width and height and i have PGLInt so i get an error Second; i cant copy the image .... Help.... Thanks....

Autor:	Coolcat [ Sa Dez 04, 2010 12:18 ]
Betreff des Beitrags:	Re: glGetTexParameteriv
A PGLInt is a pointer to an GLInt....and a pointer has to point somewhere... Code: var w1,h1: GLint; // ... glGetTexParameteri( GL_TEXTURE_2D,GL_TEXTURE_WIDTH,@w1); glGetTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_HEIGHT,@h1); Note that glTexSubImage2D does require that the texture has already sufficient size. The size of a texture is initially zero! In contrast to that glTexImage2D does delete the texture buffer and create a new one with correct size. glTexSubImage2D and glTexImage2D do read from main memory, not from another texture. If you want to copy a texture you might want to use a Framebuffer-Object and render a Fullscreen-Quad. That's faster because you don't have to download and upload the texture to graphics memory again.

Autor:	azrael11 [ Sa Dez 04, 2010 13:15 ]
Betreff des Beitrags:	Re: glGetTexParameteriv
Coolcat hat geschrieben: A PGLInt is a pointer to an GLInt....and a pointer has to point somewhere... Code: var w1,h1: GLint; // ... glGetTexParameteri( GL_TEXTURE_2D,GL_TEXTURE_WIDTH,@w1); glGetTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_HEIGHT,@h1); Note that glTexSubImage2D does require that the texture has already sufficient size. The size of a texture is initially zero! In contrast to that glTexImage2D does delete the texture buffer and create a new one with correct size. glTexSubImage2D and glTexImage2D do read from main memory, not from another texture. If you want to copy a texture you might want to use a Framebuffer-Object and render a Fullscreen-Quad. That's faster because you don't have to download and upload the texture to graphics memory again. ok i see what you mean... Now i get this results from the w1 and h1 w1 = 0 my pic is 450 width h1 = -1234354 my pic is 350 height What is that? ....... So you say that i must put the image to the memory and how can i call the image with glTexSubImage2D ? Thanks for your help...

Autor:	Coolcat [ Sa Dez 04, 2010 13:36 ]
Betreff des Beitrags:	Re: glGetTexParameteriv
Zitat: ok i see what you mean... Now i get this results from the w1 and h1 w1 = 0 my pic is 450 width h1 = -1234354 my pic is 350 height GL_TEXTURE_WIDTH and GL_TEXTURE_HEIGHT are no valid parameters for glGetTexParameter. You have to use glGetTexLevelParameter instead: glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_WIDTH, @w1); glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_HEIGHT, @h1); Zitat: So you say that i must put the image to the memory and how can i call the image with glTexSubImage2D? Note that I used C++-Syntax since I have no idea how to create a dynamic array in Delphi. Note also that you might use another internal texture format. In that case replace GL_RGBA with GL_RGB or whatever you use. You will also have to adapt the array size. Code: glBindTexture(GL_TEXTURE_2D, WhatTex); glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_WIDTH, @w1); glGetTexLevelParameteriv(GL_TEXTURE_2D, 0, GL_TEXTURE_HEIGHT, @h1); GLubyte* data = new GLubyte[w1h14]; // dynamic array of type GLubyte and size w1h14 glGetTexImage(GL_TEXTURE_2D, 0, GL_RGBA, GL_UNSIGNED_BYTE, data); // copy texture into main memory glBindTexture(GL_TEXTURE_2D, texBox); glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, w1, h1, 0, GL_RGBA, GL_UNSIGNED_BYTE, data); // upload texture to graphics memory delete[] data; // delete array As already said, a framebuffer object is MUCH faster, since the bus between graphics card and main memory is relatively slow.

Autor:	azrael11 [ Sa Dez 04, 2010 13:46 ]
Betreff des Beitrags:	Re: glGetTexParameteriv
Coolcat hat geschrieben: Zitat: As already said, a framebuffer object is MUCH faster, since the bus between graphics card and main memory is relatively slow. I know that but i have to deal with at least 20000 textures so image the amount of the memory.... As i say before THANK YOU very much for your help....

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Autor:	azrael11 [ So Dez 05, 2010 07:38 ]
Betreff des Beitrags:	Re: glGetTexParameteriv
Coolcat hat geschrieben: Zitat: GLubyte* data = new GLubyte[w1h14]; // dynamic array of type GLubyte and size w1h14 I dont understand how to convert this line in delphi format Any helph Please...

Autor:	sharkman [ So Dez 05, 2010 09:24 ]
Betreff des Beitrags:	Re: glGetTexParameteriv
Zitat: Code: GLubyte* data = new GLubyte[w1h14]; // dynamic array of type GLubyte and size w1h14 i suppose it does this: Code: var DataArr: array of GLuByte; Data: PGLuByte; begin //... SetLength(DataArr, w1h14); Data:= @DataArr; //... end;

Autor:	sharkman [ So Dez 05, 2010 09:33 ]
Betreff des Beitrags:	Re: glGetTexParameteriv
oops. an array is already a pointer. So in my code, there would be a pointer too much this should be better: Code: var Data: array of GluByte; begin //... SetLength(Data, w1h14); //... end;

Autor:	azrael11 [ So Dez 05, 2010 16:58 ]
Betreff des Beitrags:	Re: glGetTexParameteriv
sharkman hat geschrieben: oops. an array is already a pointer. So in my code, there would be a pointer too much this should be better: Code: var Data: array of GluByte; begin //... SetLength(Data, w1h14); //... end; Thank you my friend it works ...

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