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Beco

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About Beco

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  1. Thanks a lot. Today I've experienced a new feature about this topic. Rendering in feedback mode, I can get back the screen coordinates of the disappearing lines. Then I can render them in a 2D mode. The only remaining problem is about depth testing. I'm on finding a solution at the moment... As far as the ATI drivers are concerned, this fact is very annoying, I can't tell my customers to buy a new card :)
  2. I've a problem with additional clipping planes. In my application I want to use clipping planes for a section view of the model. But there is a problem when I want to render my model in wireframe mode. According to the OpenGL specification, the clipping plane should create new and visible edges for the cut polygons. It works fine on NVidia cards, rendering polygons with glPolygonMode(GL_LINE) all lines are visible. But on ATI cards the newly generated lines are dissappeared. I've tried it on several cards and neither of the ATIs displayed those lines. I can't find out the reason of this strangeness, but this isn't the first time I've had problems with GL_LINE mode on ATI cards.
  3. Yes, you have to create Rendering Context with an own pixelformat with PFD_DRAW_TO_BITMAP flag. Then create a compatible DC and a bitmap and select it for the DC. Then you can render your scene directly to the memory. Maybe you have to know that it won't use any hardware acceleration, it will be done by CPU.
  4. Beco

    Antialiased fonts

    Thx for your help! Well, I have two main problems with libraries based on FreeType. First of all, I can't tell you exactly why, but I'm a little bit afraid of the fact that they are bitmap-based. As far as I know FreeType generates an 8bpp texture for all characters, but what happens, when I have to zoom them for example. My solution has to be insensible of that. So that's why I prefer outline fonts. The other thing is, and that's the bigger problem, that, OK, even if I manage to handle Eastern-European character set, the application is multilangual, so it has to be able to display any existing font-type (Russian, Korean as well) without any special and custom development. And yes, the wgl functions can handle them but in that case antialiasing is still an existing problem. I think my problem is so special that I have to find my own way to solve it.
  5. I'm looking for a method for drawing antialiased fonts in OpenGL. In my application I have to be able to draw all installed fonts in a correct form and antialiased if possible. The result should be something like MS Word can do. Outline fonts could be good if there were any useable method for antialiasing, otherwise they look very awful at a little size. I also tried Freetype, but I couldn't manage to get it support character-sets like Eastern-European. Is there any other way?
  6. I have a problem with OpenGL tessellation method. I want to tessellate a polygon like this: The polygon after tesselation: The problem is that the line drawn with red gets a '0' edgeflag as this is a non-boundary edge. When I want to draw the wireframe model with edgeflags enabled this line disappears, so the bottom edge of the two holes won't be drawn. Is it normal? Why isn't that triangle chopped up three parts like the upper part?
  7. I'm not sure at all, but I suppose it is made by the CPU similar to the Direct3D function. I can't see how could it get the screen coordinates out from the GPU's "black box".
  8. OK, now it's getting clear for me that I must use GL_MODULATE if I want to keep lighting effects. I'm afraid I don't know exactly what color texture means but it's sure that if a face has for example a yellow color the texture gets a pale yellow tone by the modulation. I think it's time for me to get absorbed in texturing. Thanks for all your help.
  9. OpenGL feedback mode is something like that you are looking for.
  10. Maybe I can't understand your method exactly, but it seems to me that the vertex color you set is white (background.rgba). Blending can work only in that case without color distorsion.
  11. I'm not sure, but I think the problem is that your card renders the quad as a triangle strip. In that case the effect on the picture above is a feature of polygonsmooth. The main thing is - as I know - that PolygonSmooth counts an alpha value for each pixel from the percent area of the pixel hided by the polygon and modulates the already stored pixel value in framebuffer with it. In this case the pixels on the edge of the polygon will be modulated with the background color, and this will effect the gray line. In my opinion the best method for polygon antialising is multisampling.
  12. Well, maybe I didn't explain my problem correctly. My application has several display modes (it's not a game :)) like color shaded or textured. I have a color array containing RGBA components for each vertices and I use it to draw the simple coloured model without textures. In textured mode I'm using GL_MODULATE function, but the problem is exactly that, it will moddulate not only the alpha values but also the color components. The solution could be if I used white instead of my color array, but then I don't have the alpha values and the faces won't be transparent. I've also tried GL_DECAL function, it works but it killed all my lighting effects and the results were miserable. I can see the solution in only two ways: if I could use only one channel of my arrays (the alpha) and the color components could be masked out somehow with a constant white. The other is that I don't use color array at all and the texture has an alpha value. Am I correct?
  13. HI! I've a problem with drawing transparent faces with textures. My model contains RGBA color values in a vertex array and also textures. When I want to draw it with textures, I use white color to get correct results, but I still want to apply the alpha value of the vertices. Is there any special way to use only the alpha channel of my color array for the fragment color? Or if it isn't possible, how can I tell my textures to have the alpha value, so I could modulate with them the fragment's alphas? Thx
  14. If you want to draw something and see what is inside of it as well, it should be transparent (see glColor4f() and alpha value). The most simple way to draw a sphere is using quadrics.
  15. Beco

    Color problem

    The problem could be that after you have drawn a textured face, you are trying to draw a simple coloured one without texture but the texture remains bounded. Try to use glBindTexture(GL_TEXTURE_2D, NULL) if you don't want to use the texture anymore. It will solve the problem.
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