 windschuetze

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1. Getting around non-connected vertex gaps in hardware tessellation displacement mapping

Ah yes, haha, remember watching that in the mid-late 90's. Maybe worth a rewatch now that I'm old enough to actually understand it better than back then...   As for the displacement mapping I eventually settled on a rather simple approach for use with pre-existing triangle list meshes (it is by no means perfect but it seems that the "real" solution is really just having the 3D / texturing artist(s) being aware of your intents and have them author appropriately mapped bump maps and ensure corners actually are rounded, albeit with extremely short edges between corner vertices, as seemed to be the main point that the chapter in Zink, Pettineo & Hoxley (2011) as referred by unbird in the last post). Basically I average all disjoint vertex normals and create a 6-control patch index buffer that holds the initial triangle in the first 3 indices and then any "dominant" vertices sharing the position of these original vertices in the last 3 indices. The dominant vertices are arbitrarily chosen as the first found in the vertex data for a given position and are set to the same vertex as in the first three indices if there are no shared vertices at a given position. The dominant vertex is used to ensure that all overlapping vertices will sample the same value from the displacement map, while still allowing them to sample other textures by their UV coords. Not perfect but good enough for some general-purpose examples. As for actually employing this kind of displacement mapping in a more professional game / visual demo / what-have-you, the artist should ensure that there are *no* disjoint vertices (as said, such vertices can be moved slightly apart and be connected by a short edge, allowing the corners to appear mostly sharp) and a secondary set of texture coordinates should be provided for the displacement map / alternatively the displacement map should be handcrafted such that when displaced (with a reasonable strength / height factor), faces won't extrude through each others. Of course there exists more elaborate ways as described in the previous posts, I just thought I would share this if anyone found it interesting, After tracking down a copy of that practical rendering book just for that tessellation chapter, it didn't say that much more about this particular problem, so might as well save others the trouble.   Hi, im trying to implement the dominandt data, but I'm struggling again...I'm not sure how to understand the  GDC 2012 slides, when i'm generating the index buffer: vs:   I tried with the PN AEN Indexbuffer adding 3 arbitrarly chosen vertices, but it didn't worked. Then I found on the Maya Homepage a despription of a PNAEN 18 implementation using dominant data with a 18 size index buffer and I tried to adapt it. But the result isn't good either, the UVs doesn't look smoother:     My index buffer now looks like this for unbirds example: 0,1,2,0,1,4,3,2,0,0,1,4,3,2,0,0,4,2,3,4,5,2,1,4,5,5,3,4,3,4,5,5,3,4,4,5 (See also xls Attachment for details). I'm pretty sure that the shader interpolates right: float uCorner = (u == 1 ? 1:0), vCorner = (v == 1 ? 1:0), wCorner = (w == 1 ? 1:0), uEdge = (u == 0 && (v * w)!=0 ? 1:0), vEdge = (v == 0 && (u * w)!=0 ? 1:0), wEdge = (w == 0 && (u * v)!=0 ? 1:0), interior = (u * v * w)!=0 ? 1:0; vec2 displaceCoord= uCorner*InPatch.domVert +vCorner*InPatch.domVert +wCorner*InPatch.domVert +uEdge*mix(InPatch.domEdge0,InPatch.domEdge1,v) +vEdge*mix(InPatch.domEdge0,InPatch.domEdge1,w) +wEdge*mix(InPatch.domEdge0,InPatch.domEdge1,u) +interior*UV; Any clue?
2. Getting around non-connected vertex gaps in hardware tessellation displacement mapping

I solved my problem! I had serveal bugs: filling the edge map: indices[indices] instead of indices... I removed the hashing of the index and it worked! Thank you very much, I couldn't have done it without your help!   Now my cube looks smooth and crackfree:
3. Getting around non-connected vertex gaps in hardware tessellation displacement mapping

My reindexer is indeed wrong, I get totally different indices. I copied your indices manually into the vector and the cracks are gone! The shader works! I'll try to hash only the positions.  I hope that's the bug! Thank you very much for your help, the html log is awesome!   Edit: I found out that my edge Map seems to be already wrong. i have only 32 entried while your map has 36 entries.
4. Getting around non-connected vertex gaps in hardware tessellation displacement mapping

Here is my indexing code: void indexPNAEN(std::vector<unsigned short> indices, std::vector<glm::vec3> & in_vertices, std::vector<unsigned short> & out_indicesaen) { out_indicesaen.resize(indices.size()*3); //step 1 Create an output IB that is 3 times the size of input IB. //step 2 c define edge struct Edge { glm::vec3 p; short ind; bool operator == (const Edge& o) const { if (ind == o.ind && ind == o.ind) return true; if (p == o.p && p == o.p) { return true; } return false; } /* bool operator != (const Edge& o) const{ return !(*this == o); }*/ Edge reverse() { Edge returnedge; returnedge.p = p; returnedge.p = p; returnedge.ind = ind; returnedge.ind = ind; return returnedge; } }; struct KeyHasher { std::size_t operator()(const Edge& k) const { using boost::hash_value; using boost::hash_combine; // Start with a hash value of 0 . std::size_t seed = 0; // Modify 'seed' by XORing and bit-shifting in // one member of 'Key' after the other: for (int hashi = 0; hashi < 2; hashi++) { hash_combine(seed, hash_value(k.p[hashi].x)); hash_combine(seed, hash_value(k.p[hashi].y)); hash_combine(seed, hash_value(k.p[hashi].z)); hash_combine(seed, hash_value(k.ind[hashi])); } // Return the result. return seed; } }; std::unordered_map<Edge, Edge,KeyHasher> edges(indices.size()); //step 2 for (int i = 0; i < indices.size(); i += 3) //For each input Triangle in IB, { out_indicesaen[3 * i] = indices[i]; //i0 out_indicesaen[3 * i + 1] = indices[i+1]; //i1 out_indicesaen[3 * i + 2] = indices[i + 2]; //i2 out_indicesaen[3 * i + 3] = indices[i]; //i0 out_indicesaen[3 * i + 4] = indices[i + 1]; //i1 out_indicesaen[3 * i + 5] = indices[i + 1]; //i1 out_indicesaen[3 * i + 6] = indices[i+2]; //i2 out_indicesaen[3 * i + 7] = indices[i + 2]; //i2 out_indicesaen[3 * i + 8] = indices[i]; //i0 //2b and 2d Edge edge0; edge0.p = in_vertices[indices[i + 1]]; edge0.p = in_vertices[indices[i]]; edge0.ind = indices[indices[i]]; edge0.ind = indices[indices[i + 1]]; edges.emplace(edge0.reverse(), edge0); Edge edge1; edge1.p = in_vertices[indices[i + 2]]; edge1.p = in_vertices[indices[i + 1]]; edge1.ind = indices[indices[i + 1]]; edge1.ind = indices[indices[i + 2]]; edges.emplace(edge1.reverse(), edge1); Edge edge2; edge2.p = in_vertices[indices[i]]; edge2.p = in_vertices[indices[i + 2]]; edge2.ind = indices[indices[i + 2]]; edge2.ind = indices[indices[i]]; edges.emplace(edge2.reverse(), edge2); } //step 3 Walk the output index buffer (OB) constructed in step 2. For each patch of 9 indices: for (int i = 3; i < out_indicesaen.size(); i += 9) { //3a For each Edge in the current Patch, perform a lookup into Edge->Edge mapping created in step 2d. for (int k = 0; k < 6; k += 2) { int i0 = out_indicesaen[i + k]; int i1 = out_indicesaen[i + k + 1]; Edge temp; temp.ind = i1; temp.ind = i0; temp.p = in_vertices[i1]; temp.p = in_vertices[i0]; auto foundIt = edges.find(temp); if (foundIt!=edges.end()) //look up in edge vector { const Edge& second = foundIt->second; out_indicesaen[i + k] = second.ind; out_indicesaen[i + k + 1] = second.ind; } } } } Oh, thank you! IThe cube can be downloaded here. (I'm not permitted to attach an .obj file ). I'm starting to get frustrated with PNAEN...I can't find the bug for two weeks now. It's part of my master thesis.
5. Getting around non-connected vertex gaps in hardware tessellation displacement mapping

At first I used a standard cube generated by Maya and the cube stayed flat exactly as you said. Then I changed the normals of the cube like this: PN got the cracks as expected, but PN doesn't look smooth like in the graphic above and looks 100% like PN. I tried that, adding normalize in the Vertexshader, but no difference, still cracks.   Looks smooth, no cracks. No difference to flat tessealtion or PNAEN.
6. Getting around non-connected vertex gaps in hardware tessellation displacement mapping

I'm not doing any Displayment mapping so far. My TES looks like this: vec3 vp=vpos * w * w * w + b030 * u * u * u + b003 * v * v * v + InPatch.b210 * 3.0 * w * w * u + InPatch.b120 * 3.0 * w * u * u + InPatch.b201 * 3.0 * w * w * v + InPatch.b021 * 3.0 * u * u * v + InPatch.b102 * 3.0 * w * v * v + InPatch.b012 * 3.0 * u * v * v + InPatch.b111 * 6.0 * w * u * v; vec3 vn= normalize( n200 * w * w + n020 * u * u + n002 * v * v + InPatch.n110 * w * u + InPatch.n011 * u * v + InPatch.n101 * w * v ); About the screenshot above: I'm not applying any displacement yet. The cube simply cracks by smoothing the surface. As far as I understood this is a known issue with PN, but PNAEN shouldn't have this problem. I know that you meant dominant UV to solve displacement map cracking, but I still have PN cracking with PNAEN.
7. Getting around non-connected vertex gaps in hardware tessellation displacement mapping

Hi, i'm struggling with PN AEN now for two weeks and I'm not sure where my mistake could be... I'm pretty sure, the indices are correct, since I tried out unbirds exmaple and get the same indices. However my result looks like this:   I get the same result as with PN Triangles, no difference.   My TCS is: #version 420 layout (vertices = 9) out; in vec3 vp[]; in vec2 UV[]; in vec3 vn[]; out vec3 vpos[]; out vec2 outuv[]; out vec3 vnor[]; uniform vec3 tessLevelOuter; uniform float tessLevelInner; patch out Patch { vec3 b210; vec3 b120; vec3 b021; vec3 b012; vec3 b102; vec3 b201; vec3 b111; vec3 n110; vec3 n011; vec3 n101; vec2 t110; vec2 t011; vec2 t101; } OutPatch; #define b300 vp #define b030 vp #define b003 vp #define n200 vn #define n020 vn #define n002 vn #define t200 UV #define t020 UV #define t002 UV void main() { if( gl_InvocationID == 0 ) { gl_TessLevelOuter = tessLevelOuter; gl_TessLevelOuter = tessLevelOuter; gl_TessLevelOuter = tessLevelOuter; gl_TessLevelInner = tessLevelInner; } vpos[gl_InvocationID]=vp[gl_InvocationID]; vnor[gl_InvocationID]=vn[gl_InvocationID]; outuv[gl_InvocationID]=UV[gl_InvocationID]; if( gl_InvocationID == 0 ) { OutPatch.b210 = (2.0 * b300 + b030 - dot( b030 - b300, n200 ) * n200 + 2.0 * vp + vp - dot( vp - vp, vn ) * vn ) / 6.0; OutPatch.b120 = (2.0 * b030 + b300 - dot( b300 - b030, n020 ) * n020 +2.0 * vp + vp -dot( vp - vp, vn ) * vn ) / 6.0; OutPatch.b021 = (2.0 * b030 + b003 - dot( b003 - b030, n020 ) * n020 +2.0 * vp + vp - dot( vp - vp, vn ) * vn ) / 6.0; OutPatch.b012 = (2.0 * b003 + b030 - dot( b030 - b003, n002 ) * n002 +2.0 * vp + vp - dot( vp - vp, vn ) * vn ) / 6.0; OutPatch.b102 = (2.0 * b003 + b300 - dot( b300 - b003, n002 ) * n002 +2.0 * vp + vp -dot( vp - vp, vn ) * vn ) / 6.0; OutPatch.b201 = (2.0 * b300 + b003 - dot( b003 - b300, n200 ) * n200 + 2.0 * vp + vp -dot( vp - vp, vn ) * vn ) / 6.0; OutPatch.b111 = (OutPatch.b210 + OutPatch.b120 + OutPatch.b021 + OutPatch.b012 + OutPatch.b102 + OutPatch.b201) / 4.0 - (b300 + b030 + b003) / 6.0; const vec3 d0 = b030 - b300; const vec3 d1 = b003 - b030; const vec3 d2 = b300 - b003; const vec3 n0 = n020 + n200; const vec3 n1 = n002 + n020; const vec3 n2 = n200 + n002; const vec3 v0 = (2.0 * dot( d0, n0 ) / dot( d0, d0 )) * d0; const vec3 v1 = (2.0 * dot( d1, n1 ) / dot( d1, d1 )) * d1; const vec3 v2 = (2.0 * dot( d2, n2 ) / dot( d2, d2 )) * d2; OutPatch.n110 = normalize( n0 - v0 ); OutPatch.n011 = normalize( n1 - v1 ); OutPatch.n101 = normalize( n2 - v2 ); } } Any ideas what I'm doing wrong?