opengl paint program based on Apple's 'glPaint' on a white background - how to blend?

Posted by Adam on Stack Overflow See other posts from Stack Overflow or by Adam
Published on 2010-05-08T01:23:22Z Indexed on 2010/05/08 1:28 UTC
Read the original article Hit count: 560

Filed under:

opengl-es

|

paint

|

iphone

|

opengl

|

blending

Trying to write a simple paint program for iPhone, and I'm using Apple's glPaint sample as a guide. The only problem is, painting doesn't work on a white background, since white + colour = white. I've tried different blending functions, but haven't been able to hit on the right combination of settings and/or brushes to make this work. I've seen similar posts about this problem but no answers. Does anyone know how this might work?

© Stack Overflow or respective owner

Related posts about opengl-es

Tutorials and libraries for OpenGL-ES games on Android

as seen on Stack Overflow - Search for 'Stack Overflow'
What tutorials and libraries are available which can help beginners to develop 2D and 3D games on Android using OpenGL-ES? I'm looking for tutorials which can help me learn OpenGL-ES, and I'm looking for OpenGL-ES libraries which can make life easier for beginners in OpenGL-ES. Since Android is still… >>> More
Can I upgrade UIRequiredDeviceCapabilities from opengles-1 to opengles-2 in iOS app

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi I’m upgrading my app from cocos2d-x 1.x to 2.x that means change from OpenGLES 1.0 to 2.0, I've updated my Info.plist settings to reflect the change <key>UIRequiredDeviceCapabilities</key> <dict> <key>accelerometer</key> <true/> <key>opengles-2</key> … >>> More
Where are some good resources to learn Game Development with OpenGL ES 2.X

as seen on Game Development - Search for 'Game Development'
Background: From http://www.khronos.org/opengles/2_X/ OpenGL ES 2.0 combines a version of the OpenGL Shading Language for programming vertex and fragment shaders that has been adapted for embedded platforms, together with a streamlined API from OpenGL ES 1.1 that has removed any fixed functionality… >>> More
[OpenGL ES - Android] Better way to generate tiles

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi ! I'll start by saying that i'm REALLY new to OpenGL ES (I started yesterday =), but I do have some Java and other languages experience. I've looked a lot of tutorials, of course Nehe's ones and my work is mainly based on that. As a test, I started creating a "tile generator" in order to create… >>> More
iPod/iPhone OpenGL ES UIView flashes when updating

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a simple iPhone application which uses OpenGL ES (v1) to draw a line based on the touches of the user. In the XCode Simulator, the code works perfectly. However, when I install the app onto an iPod or iPhone, the OpenGL ES view "flashes" when drawing the line. If I disable the line drawing… >>> More

Related posts about paint

Architecture of interaction modes ("paint tools") for a 3D paint program

as seen on Programmers - Search for 'Programmers'
We are developing a Qt-based application to navigate through and paint on a volume treated as a 3D pixel graphic. The layout of the app consists of three orthogonal slice views on which the user may paint stuff like dots, circles etc. and also erase already painted pixels. Think of a 3D Gimp or MS… >>> More
adding onTap method on path direction between 2 point

as seen on Stack Overflow - Search for 'Stack Overflow'
I have a problem in my Android application I have a path direction on my application and I want to add an onTap method for the path, so if I touch that path my application will display information with alert dialog. This my activity code: hasilrute hr = new hasilrute(); for (int k = 0;k < hr… >>> More
select a diagonal area in paint.net

as seen on Super User - Search for 'Super User'
In Paint.net, is it possible to select a quadrilateral area with diagonal faces? How? >>> More
To make the drawn text clear

as seen on Stack Overflow - Search for 'Stack Overflow'
I have written the code to draw text on the image and to save the image,But the text which I am drawing is looking blur on the image.What modifications need to do to make it clear,Or if there is any other way to draw text on image in android Canvas canvas = new Canvas(photo); Typeface… >>> More
Starting Your Own Website - Paint by Numbers is the Beginner's Way to Go

as seen on Ezine Articles - Search for 'Ezine Articles'
Fancy starting your own website, perhaps a blog or article page, why not? Seems everyone has some form of online profile these days for various reasons, keeping in contact, self or business promotion, becoming a advocate and many other. >>> More