GLSL: Unable to find compatible overloaded function - glsl

Question

I am trying to write a fragment shader and I've hit a wall. This is only my second shader so I'm very new to this and I'm almost certain I'm just not dealing with the data types properly and that's where the error is coming from but for the life of me I can't seem to fix it. The goal is to be able to pass a texture to the function so I can call it again and again... Any and all help would be appreciated!
The error I get is: error C1115: unable to find compatible overloaded function "texture2D(vec3, vec2)".
uniform sampler2D image;
uniform float radius;
uniform float adsk_result_w, adsk_result_h;
vec2 iResolution = vec2(adsk_result_w, adsk_result_h);
vec2 uv=(gl_FragCoord.xy/iResolution.xy);
vec2 vTexCoord = (gl_FragCoord.xy/iResolution.xy);
float blurSize = radius/iResolution;
vec4 hblur(vec4 frontin ) {
vec3 RTScene = frontin.rgb;
vec4 sum = vec4(0.0);
sum += texture2D(RTScene, vec2(vTexCoord.x - 4.0*blurSize, vTexCoord.y)) * 0.05;
sum += texture2D(RTScene, vec2(vTexCoord.x - 3.0*blurSize, vTexCoord.y)) * 0.09;
sum += texture2D(RTScene, vec2(vTexCoord.x - 2.0*blurSize, vTexCoord.y)) * 0.12;
sum += texture2D(RTScene, vec2(vTexCoord.x - blurSize, vTexCoord.y)) * 0.15;
sum += texture2D(RTScene, vec2(vTexCoord.x, vTexCoord.y)) * 0.16;
sum += texture2D(RTScene, vec2(vTexCoord.x + blurSize, vTexCoord.y)) * 0.15;
sum += texture2D(RTScene, vec2(vTexCoord.x + 2.0*blurSize, vTexCoord.y)) * 0.12;
sum += texture2D(RTScene, vec2(vTexCoord.x + 3.0*blurSize, vTexCoord.y)) * 0.09;
sum += texture2D(RTScene, vec2(vTexCoord.x + 4.0*blurSize, vTexCoord.y)) * 0.05;
return vec4(sum);
}
void main() {
vec4 front = texture2D(image, uv);
vec4 work = hblur(front);
gl_FragColor = vec4(work);
}

Answer 1

As the error message tells you there is no texture2D overload that expects a vec3 as first and a vec2 as second argument. The first argument of texture2D has to be a of the type sampler2D.
Literally you tell OpenGL in your code with texture2D(RTScene, vec2(vTexCoord.x, vTexCoord.y)) to look for the color at position vec2(vTexCoord.x, vTexCoord.y) in the texture RTScene. But as RTScene is just a vec3 containing three floats (the rgb value you retrieved in the main), where should OpenGL find the pixel.
In your main code you would have something like this:
vec4 work = hblur(image, uv);
And your hblur should look something like this:
vec4 hblur(sampler2D tex, vec2 uv) {
// your other code
sum += texture2D(tex, vec2(uv.x - 4.0*blurSize, uv.y)) * 0.05;
// your other code
}
It is always helpful to look at the OpenGL Quick Reference Card for the OpenGL version your are coding for, there you will have a quick overview over the available functions:
OpenGL 3.2 API Reference Card
OpenGL 4.1 API Reference Card
OpenGL 4.2 API Reference Card