[1.6.4] [OpenGL] Problem with matrix position after scaling

[RedEnergy]

Hello everyone, i need to draw picture on screen and make it a bit larger. I am doing this code:

@ForgeSubscribe
public void onGuiRendering(RenderGameOverlayEvent.Post event)
{
	this.width = event.resolution.getScaledWidth();
	this.height = event.resolution.getScaledHeight();
     if(event.type == ElementType.ALL) {
    	 GL11.glPushMatrix();
         GL11.glPushAttrib(GL11.GL_ENABLE_BIT);
         GL11.glEnable(GL11.GL_ALPHA_TEST);
         GL11.glAlphaFunc(GL11.GL_GREATER, 0.1F);
         GL11.glScalef(1.7F, 1.7F,1.7F);
	//pic goes here
	  GL11.glPopAttrib();
	  GL11.glPopMatrix();
      }
}

My problem is in glScalef(), after this method picture move away from the position which i am rendering it on. How to return it?

 

[TheGreyGhost]

Hi

 

Try GL11.glTranslatef(deltaX, deltaY, deltaZ);

You should be able to figure out the correct values with a couple of trial and error.

 

In general you need to combine scaling and translation to make sure that your shape scales around the correct centrepoint.

 

This image illustrates the problem when doing a rotation, the concept is the same for scaling.

http://www.glprogramming.com/red/images/Image52.gif

 

For more info see here

http://www.glprogramming.com/red/chapter03.html

 

-TGG

 

[RedEnergy]

I still dont understood how to do this, i tried to do in sush way

@ForgeSubscribe
public void onGuiRendering(RenderGameOverlayEvent.Post event)
{
	this.width = event.resolution.getScaledWidth();
	this.height = event.resolution.getScaledHeight();
     if(event.type == ElementType.ALL) {
    	 GL11.glPushMatrix();
         GL11.glPushAttrib(GL11.GL_ENABLE_BIT);
         GL11.glEnable(GL11.GL_ALPHA_TEST);
         GL11.glAlphaFunc(GL11.GL_GREATER, 0.1F);
         GL11.glScalef(1.7F, 1.7F,1.7F);
         GL11.glTranslated(1.7F, 1.7F, 1.7F);
		 ri.renderItemIntoGUI(mc.fontRenderer, mc.getTextureManager(), new ItemStack(Item.pocketSundial), (int) ((int) (this.width / 2 ) / 1.7F),  100);
	     GL11.glPopAttrib();
	     GL11.glPopMatrix();
      }
} 

 

But it still not in the middle of x-axis

[Nephroid]

It seems like you are trying to draw a 2D image. You shouldn't have to bother with z coordinates then.

 

That is, when you're calling

glScalef

, you should use 1 for the z-scale:

GL11.glScalef(x, y, 1);

 

Similarly, you also want to ignore the z-axis when you're translating too (if you still need to translate):

GL11.glTranslatef(x, y, 0);

[Eternaldoom]

Also, update to 1.7.10 or 1.8. 1.6.4 is severely outdated.

[TheGreyGhost]

>         GL11.glTranslated(1.7F, 1.7F, 1.7F);

But it still not in the middle of x-axis

then try other values until it looks right...

For example

GL11.glTranslated(10, 0, 0);

then change it to

GL11.glTranslated(100,0,0);

then change it to

GL11.glTranslated(-50,0,0);

etc

eventually you will find the value of deltax which translates the image to the correct location.

 

-TGG