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Type: Posts; User: bsabiston

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  1. Replies
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    how to use texture combiners?

    Hello,

    I am having a hard time finding good information about texture combiners. Can they be used to draw a texture half-transparently? The texture already has its own alpha mask which defines...
  2. find the corners of the screen at a given depth?

    Hello,

    If I have a rectangle facing the screen in my scene, how can I determine the four corners so that it fills the screen exactly? In other words I think I want the four points where the...
  3. painting into texture buffer with transparency, overlapping issues

    Hello,

    I am trying to draw an interactive line with openGL triangles, which is working fine. But when I try to draw it at opacity <1, ie with some level of alpha transparency, the colors build...
  4. Still want to know how to do this! Anyone?

    Still want to know how to do this! Anyone?
  5. nobody knows?

    nobody knows?
  6. noob question shifting the scene left or right?

    Hello,

    Currently in my game, I have a 3D scene which centers in the middle of the screen. That is, my player is in the middle of the screen, and when I rotate the camera, it rotates around the...
  7. Getting overhead rotation angle from matrix?

    Hello,

    I have what I believe to be a typical OpenGL camera setup. I need to figure out the rotation angle of the camera around the Y axis. I have been doing this by getting the Euler angles...
  8. Replies
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    884

    Shadow mapping question

    Hello,

    I am trying to use shadow mapping in my game. I ported some sample code over and finally have it working for the most part. However, I am getting some bad artifacts whenever an object...
  9. Replies
    3
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    612

    Actually, past a certain version of GLSL, you...

    Actually, past a certain version of GLSL, you have to define it yourself, like this:

    out vec4 fragColor;
  10. Replies
    3
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    612

    frag shader compile error

    Hello,

    I have a simple frag shader that is not compiling on OS X. It says it does not know 'fragColor', but that is built-in, isn't it? I use it in all my other frag shaders but this one is...
  11. Replies
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    1,050

    conditionals in shaders

    Hello,

    I am pretty new to shader programming, and I have read that it is not great to use conditionals in them to have the shader perform different tasks depending on some outside state. Is...
  12. Replies
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    Yes I think that is what I want! Unfortunately...

    Yes I think that is what I want! Unfortunately OpenGLES2 doesn't do geometry shaders, but that article mentions an earlier technique that does not need them.

    Thanks,
    Bob
  13. Replies
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    910

    But if the 'lines' are in 3D, you still have the...

    But if the 'lines' are in 3D, you still have the problem of them becoming invisible when seen edge-on.
  14. controlling 3d movement from a virtual d-pad

    Hello,

    In my game I have a circle on screen indicating a steering wheel or direction pad. Depending on the position of the finger relative to the center of the circle, I want to move in that...
  15. Thread: color alpha?

    by bsabiston
    Replies
    2
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    1,199

    Yes, it is enabled. I do see transparency, but...

    Yes, it is enabled. I do see transparency, but just not how I expect. Basically I am accustomed to thinking "oh if I want a half-transparent red color, will set it to RGBA 1.0 0.0 0.0 0.5"

    But it...
  16. best simple antialiasing of lines -- textures or alpha vertices?

    Hello,

    I have read that a good way to antialias lines in openGl is to use a texture map of an antialiased circle and map the coordinates of a rectangular set of vertices to it, like this:
    ...
  17. Replies
    5
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    910

    Nobody? What do most people do if they want to...

    Nobody? What do most people do if they want to draw antialiased lines in 3D space?
  18. Replies
    5
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    910

    rotating faces to face the camera?

    Hello,

    I want to draw an antialised wireframe cube, with lines of a certain width (greater than 1). In OpenglES 2, on my devices at least, this isn't supported.

    I've had some success drawing...
  19. Thread: color alpha?

    by bsabiston
    Replies
    2
    Views
    1,199

    color alpha?

    Hello,

    When I set my vertex color in my glsl vertex shader like this, it doesn't do what I expect. Specifically I expect that setting the alpha to 0 would cause the vertex to be transparent. ...
  20. Replies
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    902

    speed of glBindVertexArray

    Hello,

    I have been working on a voxel engine for terrain, similar to mine craft. Online there are many tutorials about this. One of the optimizations that is frequently discussed involves...
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    lowp question (iOS/Mac differences)

    Hello,

    I have a shader which works on Mac OS X but not in iOS. I am passing an array of unsigned chars as the position attribute. In the shader, it's defined like this:

    in lowp vec4position;
    ...
  22. Awesome! Thanks very much Bob

    Awesome! Thanks very much
    Bob
  23. vertex shader with color attribute question

    Hello,

    I am drawing a bunch of 2D objects using OpenGLES 2.0, so I have vertex and fragment shaders. Some of the objects have color data at each vertex, and some of the objects are all one...
  24. Yeah, I found that I had set the blend wrong. It...

    Yeah, I found that I had set the blend wrong. It was :

    glBlendFunc (GL_ONE, GL_ONE_MINUS_SRC_ALPHA);

    instead of this, which seems to work more like what I want:

    ...
  25. Replies
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    why are my objects translucent?

    Hello,

    I have this shader and it is turning all of my objects translucent. From the code it looks to me like the color's alpha value will always be 1, but it is not. If I explicitly set...
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