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Type: Posts; User: esapir

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  1. Calculating orthographic matrix parameters from perspective matrix

    I have the following two matrix creation methods:

    GLK_INLINE GLKMatrix4 GLKMatrix4MakePerspective(float fovyRadians, float aspect, float nearZ, float farZ)
    {
    float cotan = 1.0f /...
  2. Finding intersection of a ray with arbitrary surface

    I want to check if a user clicked on a surface. In this case the surface is a coons patch.

    What should be the algorithm to finding an intersection of the click point (a ray) with the surface?
  3. Creating a surface from a closed path composed from bezier curves

    I have a closed path, composed of N bezier curves with 3D coordinates. I would like to create a triangulated surface from this path.
    Is there a known algorithm for creating a surface from such a...
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    Creating smooth curve from sampled points

    I am creating sort of a 'paint' application in which use can draw free curves. If i draw the sampled points as is, the curve does not look smooth.

    I tried the algorithm in the following tutorial:...
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    Drawing 3D curve with varying width

    I am trying to draw a curve in 3D in which the width may vary. I am doing something similar to what described in the following tutorial:...
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    Drawing lines with changing width

    I am looking for a way to draw 3D lines with changing width. I know that i can create triangles, as in the following tutorial:...
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    My background is a gradient drawn using two...

    My background is a gradient drawn using two rectangles (colors of the vertices with y=0 are not equals to the colors of the vertices with y=height). If i understand correctly, the fog color i use...
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    It am not sure how to make it work when i have a...

    It am not sure how to make it work when i have a gradient background - the fog color changes from pixel to pixel.
    How i can i achieve the fog effect without using alpha blending?
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    Blended lines do not look as expected

    I use the following fragment shader, which uses the fog effect, to draw my scene:


    precision mediump float;

    uniform int EnableFog;
    uniform float FogMinDist;
    uniform float FogMaxDist;
    ...
  10. Drawing smoothly connected lines with width

    I am trying to draw lines that should be and look connected. The problem is that when the width is not 1.0, the edges don't really look connected.
    Is there a way to fix it without drawing the lines...
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    How i can draw a quad with screen coords?

    How i can draw a quad with screen coords?
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    Drawing background gradient

    I would like to set the background with gradient instead of a single color. Is it possible ?
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    Thanks, i will try that

    Thanks, i will try that
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    One vertex buffer with varying with

    I would like to draw lines from one vertex buffer but with changing width. Is it possible?
  15. Great answer!

    Great answer!
  16. How can i make far objects look fading or transparent?

    Say i have a 3D rectangle, rotated 45 degrees as in the attached screenshot. I would like the lines and the far edge (A) to look fading. Moreover, when i rotate the camera, i want the 'new' far lines...
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    You are correct of course. I had another bug that...

    You are correct of course. I had another bug that i fixed after that.
    All works well now. thanks!
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    Depth test not working

    I am using OpenGL ES 2.0 on iOS. I enabled DEPTH_TEST, but still object that should be hidden are rendered.
    See screenshots:

    http://postimg.org/image/9kp5ltcx7/50d44327/...
  19. It was also my intuition - that i need to...

    It was also my intuition - that i need to construct quads. However, there are several problems that i am not sure how to solve:

    1. Number of points on the curves is not equal and more than that -...
  20. I think this kind of solution will work only for...

    I think this kind of solution will work only for planar polygons. I don't think it will work for real 3D polygons
  21. Triangulating a surface constructed by 3D curves

    I have a 3D polygon (i wonder if polygon is the correct term here) that is constructed from 3D curves. These curves are basically lists of 3D points.

    I would like to triangulate this surface so i...
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