Tessellation and Dynamic UV Mapping (Resolve)

Troubleshooting graphics
1

Alright, I have a huge issue with my tessellation and i need help understanding the problem.

I m generating 4 Quads which i do manual Mapping on them for now, The mapping is done like that

    Quad box;
    box = new Quad(10 * (xEnd - xStart), 20 * (yEnd - yStart));

    box.clearBuffer(VertexBuffer.Type.Index);
    box.setBuffer(VertexBuffer.Type.Index, 4, BufferUtils.createIntBuffer(0, 1, 2, 3));
    box.setMode(Mesh.Mode.Patch);
    box.setPatchVertexCount(4);

    
    
    Vector2f[] texCoord0 = new Vector2f[4];
    texCoord0[0] = new Vector2f(0.0f, 0);
    texCoord0[1] = new Vector2f(0.2f, 0f);
    texCoord0[2] = new Vector2f(0.2f, 1f);
    texCoord0[3] = new Vector2f(0.0f, 1f);
    
    Vector2f[] texCoord1 = new Vector2f[4];
    texCoord1[0] = new Vector2f(0.20f, 0f);
    texCoord1[1] = new Vector2f(0.40f, 0f);
    texCoord1[2] = new Vector2f(0.40f, 1f);
    texCoord1[3] = new Vector2f(0.20f, 1f);


    Vector2f[] texCoord2 = new Vector2f[4];
    texCoord2[0] = new Vector2f(0.40f, 0f);
    texCoord2[1] = new Vector2f(0.60f, 0f);
    texCoord2[2] = new Vector2f(0.60f, 1f);
    texCoord2[3] = new Vector2f(0.4f, 1f);

    Vector2f[] texCoord3 = new Vector2f[4];
    texCoord3[0] = new Vector2f(0.60f, 0f);
    texCoord3[1] = new Vector2f(0.80f, 0f);
    texCoord3[2] = new Vector2f(0.80f, 1f);
    texCoord3[3] = new Vector2f(0.60f, 1f);
    
    //Later Clone and Map are set For Each Of Them
    box.setBuffer(Type.TexCoord, 2, BufferUtils.createFloatBuffer(texCoord0));

From there i did test with a Unshaded Material and the Visual was perfectly fine(Btw i didn’t do the remapping of VerticeBuffer only the texture UV position), But once i use this on My own MatDefinition for Tessellation, The mapping get all messed up. There seem to be a side Pulling toward a specific Direction.

I know it won’t be easy to trouble shoot the problem but there is 2 place it goes wrong, The first is the code up there, the second is Tessellation Evaluation Shader which doesn’t have the write formula for UV mapping.

vec2 interpolate2D(vec2 v0, vec2 v1, vec2 v2, vec2 v3)
{
    return v0 + vec2(gl_TessCoord.x) *  v1 + vec2(gl_TessCoord.xy) * v2 +  vec2(gl_TessCoord.y) *v3;
}
void main(){

return v0 + vec2(gl_TessCoord.y) *  v1.y + vec2(gl_TessCoord.yx) * v2 +  vec2(gl_TessCoord.x) *v3.x;

}

Does anyone know how i could fix this issue

picture for visual people

2017.03.22-15.17.png1920Ă—1080 2.14 MB

2

i used alway a method like this for quad tessellation:

// interpolate in horizontal direction between vert. 0 and 3
vec3 p0 = mix(tcPosition[0], tcPosition[3], gl_TessCoord.x);
// interpolate in horizontal direction between vert. 1 and 2
vec3 p1 = mix(tcPosition[1], tcPosition[2], gl_TessCoord.x);
// interpolate in vert direction
vec3 p = mix(p0, p1, gl_TessCoord.y);
1 Like
3

Yea but it doesn’t move the texture? I use exactly your code in but how do i get the Texture Position per vertice?

4

omg I just toke the code and INstead of applying it as a gl_Position i use it as a TessCoord and as you said everything is working just find, you are a life saver !

For anyone wondering what was the anwser

vec2 interpolate2D(vec2 v0, vec2 v1, vec2 v2, vec2 v3)
{
    //return v0 + vec2(gl_TessCoord.y) *  v1.y + vec2(gl_TessCoord.yx) * v2 +  vec2(gl_TessCoord.x) *v3.x;
   //this instead
    return vec2(mix(mix(v0,v3,gl_TessCoord.x), mix(v1,v2,gl_TessCoord.x) , gl_TessCoord.y));
}