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Author Topic: Achiving some sort of projection texture mapping  (Read 3586 times)

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Bimblorio

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Achiving some sort of projection texture mapping
« on: April 12, 2021, 06:57:39 pm »
I'm trying to achieve an effect, where repeated texture stays in place even if object (shape or sprite) is movig.
Is there any easy way to do it?
Is there any way to do it without using shaders?
Thanks in advance.
« Last Edit: April 12, 2021, 07:04:00 pm by Bimblorio »

eXpl0it3r

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Re: Achiving some sort of projection texture mapping
« Reply #1 on: April 13, 2021, 01:12:48 pm »
By "in place" do you mean that it's the same relative to the window or relative to the moving object?

Which object are you moving exactly?
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Bimblorio

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Re: Achiving some sort of projection texture mapping
« Reply #2 on: April 13, 2021, 06:45:16 pm »
By "in place" do you mean that it's the same relative to the window or relative to the moving object?
Relative to the window.

Which object are you moving exactly?
Shape

kojack

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Re: Achiving some sort of projection texture mapping
« Reply #3 on: April 14, 2021, 03:39:35 am »
One way would be messing with UV coordinates each frame.

Or you can use a shader. Here's a quick test hack I just made:
Vertex shader:
void main()
{
    // transform the vertex position
    gl_Position = gl_ModelViewProjectionMatrix * gl_Vertex;

    // transform the texture coordinates
    gl_TexCoord[0] = gl_Vertex/64;

    // forward the vertex color
    gl_FrontColor = gl_Color;
}
Fragment shader:
sampler2D texture;
void main()
{
    // lookup the pixel in the texture
    vec4 c = texture2D(texture, gl_TexCoord[0].xy);
    gl_FragColor = c;
}
 

Applied to a sprite, that made the sprite's texture (which was set to repeat) stay in place as the sprite moved.
The 64 in the vertex shader was the resolution of the sprite's texture.

Laurent

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Re: Achiving some sort of projection texture mapping
« Reply #4 on: April 14, 2021, 09:19:00 am »
Or just set the sprite's textureRect to its global bounding rectangle whenever it moves ;)
Laurent Gomila - SFML developer

kojack

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Re: Achiving some sort of projection texture mapping
« Reply #5 on: April 14, 2021, 11:05:17 am »
Well, sure, if you want to do it the easy and sensible way...
:)

Bimblorio

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Re: Achiving some sort of projection texture mapping
« Reply #6 on: April 14, 2021, 05:23:32 pm »
Wow so many options, thank you everyone.
Ill choose something that sutes me.

 

anything