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blueshogun96

OpenGL Why can't I change the vertex colour when the texture is alpha only?

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blueshogun96    2265

For OpenGL ES, I'm working on an iOS game which uses a pre-written font class.  It works great, but I can't change the vertex colour of the primitives used to draw the text.

 

I'm using this code here: http://www.themusingsofalostprogrammer.com/2010/01/how-to-do-font-rendering-in-opengl-on.html

 

I tried to modify the code so I could change the vertex colour, but it doesn't seem to effect it.  Before you say it, I can't use a vertex/fragment program because I'm using a 1st gen iPod which doesn't support it.  Any other ideas?  Would love to share more, but I'm on a bus w/ wifi and I'm about to get off; my stop is coming up.

 

Shogun

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blueshogun96    2265

For starters, glColor and friends aren't supported on OpenGL ES.

 

Second, I did modify the vertex array code to include a diffuse colour for each vertex, but that didn't change anything either.

 

Is there a way to do this using glTexEnv?  This is a bit tougher than I thought. blink.png

 

Shogun.

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SimonForsman    7642
glColor4f is available in ES1.0/1.1 (you're right that 3f is missing though), just set alpha to 1.0

do a glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); as well before you render and it should multiply the vertex color with the texture color

You do not need a color array unless you want different colors for each vertex.

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blueshogun96    2265

Are you sure glColor4f is supported in OpenGL ES 1.1?  Once again, XCode is telling me that it's undefined.  I had to remove it before, and I can't find a definition for it anywhere.

 

I tried using glTexEnvi(...) and it still didn't work.  

 

Shogun.

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SimonForsman    7642

Are you sure glColor4f is supported in OpenGL ES 1.1?  Once again, XCode is telling me that it's undefined.  I had to remove it before, and I can't find a definition for it anywhere.

 

I tried using glTexEnvi(...) and it still didn't work.  

 

Shogun.

 

Yes, glColor4f is available in OpenGL:ES 1.1 (its not in 2.0 though)

 

GL_API void GL_APIENTRY glColor4f (GLfloat red, GLfloat green, GLfloat blue, GLfloat alpha);


should be in OpenGLES/ES1/gl.h (or whatever path you use on iOS)

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blueshogun96    2265

Okay, it's working now.  I don't know why, but it's working now.

 

I reopened the project and it just started compiling without error.  Meh, unless I subconsciously spelled it as glColour4f, I have no idea why it wasn't working before.  Well, that did the trick.  Now I feel stupid again...

 

I'll give you both ratings for your troubles >.<

 

Shogun

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tom_mai78101    693

I'll tell you why it didn't work before, but it worked afterwards.

 

Reason: You didn't refresh/clean your project. XCode may happened to have some old data that's hiddenly conflicting. Sometimes, it happens on my Eclipse for Java/Android.

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