GLSL color channel offset problem

Troubleshooting graphics
1


I tried to create the post-effects, use of Common/Pos.vert and my custom.frag

frag
frag1920×1080

result
result
result1920×1080

then add the offset of the red channel
frag
frag1920×1080

result
reslut
reslut1920×1080

Why, instead of the offset of the red channel there are red lines?

2

Which effect do you try to do ?

texCoord in range ([0.0,1.0], [0.0,1.0]) if you substract (1.0,0.0) you will have a negative texCoord params, behavior depends of clamp (see OpenGL - Textures). IMHO (hypothesis), you’re in GL_CLAMP_TO_EDGE => your red is always with a texCoord(0, [0.0,1.0]) so if the pixel at the “begin of the line” is red, you’ll see red line.

3

yeah, david is right. I think i understand what you try to create. If i get it correctly you would like to be able to set the offset in pixels.


vec2f blueTexCoord=inTexCoord-(blueOffset/screenResolution);
4 
uniform vec2 g_Resolution;

uniform sampler2D m_Texture;
uniform sampler2D m_DepthTexture;

in vec2 texCoord;
out vec4 outFragColor;

void main () {
	
    
	vec2 greenTexCoord = texCoord - (vec2(1,0) / g_Resolution); 
	
    vec4 redValue = texture2D(m_Texture, texCoord);  
    vec4 greenValue = texture2D(m_Texture, greenTexCoord);
    vec4 blueValue = texture2D(m_Texture, texCoord);  

    outFragColor = vec4(0, greenValue.g, 0, 1.0);
}

:frowning:

1920×1080

5

Hm solid green is a strange output.

Sure the texCoord and g_Resolution is porperly passed to the shader?

texCoord would be easy to debug… not sure about g_Resolution. (as a note: you have to add Resolution to your j3md)

6
(as a note: you have to add Resolution to your j3md)
thanks :)
7

Fine, you 're creating blue red stereoscopic 3D effect (http://en.wikipedia.org/wiki/Anaglyph_3D ).

8

Beside that, this effect was heavily in use in battlefield 4. For cutscenes, menu changes, teasers… like everywhere.