So i created a texture with 50% Transparency but when i load it into minecraft it rensers like a Solid.

What can i do?

Up is what it should look like. [added w/ Paint.NET]

Down what it renders. [using the code below]

	@ForgeSubscribe
public void TestRender(RenderGameOverlayEvent.Post event){
	//========Resolution========
	res = new ScaledResolution(mc.gameSettings, mc.displayWidth, mc.displayHeight);
	int width = res.getScaledWidth();
	int height = res.getScaledHeight();
	//========Resolution========+

   	this.mc.renderEngine.func_110577_a(new ResourceLocation("/Num/Chintzy/" + "Preview" + ".png"));
    	drawTexturedModalRect(100, 100, 0, 0, 500, 500);
    	mc.func_110434_K().func_110577_a(Gui.field_110324_m);
    	
}

Before you call drawTextureModalRect, call glColor. Example for 50% transparency:

 

@ForgeSubscribe
public void TestRender(RenderGameOverlayEvent.Post event){
	//========Resolution========
	res = new ScaledResolution(mc.gameSettings, mc.displayWidth, mc.displayHeight);
	int width = res.getScaledWidth();
	int height = res.getScaledHeight();
	//========Resolution========+

	this.mc.renderEngine.func_110577_a(new ResourceLocation("/Num/Chintzy/" + "Preview" + ".png"));
	[b]GL11.glColor4f(1, 1, 1, 0.5f);[/b]
	drawTexturedModalRect(100, 100, 0, 0, 500, 500);
	mc.func_110434_K().func_110577_a(Gui.field_110324_m);
}

no. you have to enable blending

 

GL11.glEnable(GL11.GL_BLEND);

no. you have to enable blending

 

GL11.glEnable(GL11.GL_BLEND);

 

Right... What was I thinking?

well even if you do call glColor it wont work unless blending is enabled, and bte its a bad practice to call glColor except when using a colorless texture that you want to programmatically change the color of. in his case the image seems/should be completelly baked in the image

Nope.. still nothing.. 

 

	@ForgeSubscribe
public void ArmorlvlTest(RenderGameOverlayEvent.Post event){

	//========Resolution========
	res = new ScaledResolution(mc.gameSettings, mc.displayWidth, mc.displayHeight);
	int width = res.getScaledWidth();
	int height = res.getScaledHeight();
	//========Resolution========+
	this.mc.renderEngine.func_110577_a(new ResourceLocation("Num/Chintzy/Preview.png"));

        GL11.glEnable(GL11.GL_BLEND);
        GL11.glColor4f(1, 1, 1, 0.5f);
        drawTexturedModalRect(width-120, height-80, 75, 105, 110, 50);
    	mc.func_110434_K().func_110577_a(Gui.field_110324_m);
    	
}

You need the push/popMatrix...

 

So this:

        @ForgeSubscribe
public void ArmorlvlTest(RenderGameOverlayEvent.Post event){

	//========Resolution========
	res = new ScaledResolution(mc.gameSettings, mc.displayWidth, mc.displayHeight);
	int width = res.getScaledWidth();
	int height = res.getScaledHeight();
	//========Resolution========+
	this.mc.renderEngine.func_110577_a(new ResourceLocation("Num/Chintzy/Preview.png"));

        GL11.glPushMatrix();

        GL11.glEnable(GL11.GL_BLEND);

        drawTexturedModalRect(width-120, height-80, 75, 105, 110, 50);
    	mc.func_110434_K().func_110577_a(Gui.field_110324_m);

        GL11.glPopMatrix();
    	
}

You need the push/popMatrix...

 

"push" stops every other texture in the game from rendering...

"pop" does nothing... 

Lol.... Try using the PRE render event. And I know what I am talking about with those two statements I think you will find. Without them, openGL does NOTHING.

 

But that about nearly covers what I do know about openGL... I can do translation, rotation and resizing. That is about it.

I could be way off here and just a shot in the dark, but you may need to add an alpha mask to the image.  Saving regular transparency ive noticed like with liquid blocks they wont render partially transparent without an alpha mask.