fix and improve GenMeshTangents
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Bigfoot71
parent
63b988ade9
commit
d135eef462
1 changed files with 96 additions and 41 deletions
131
src/rmodels.c
131
src/rmodels.c
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@ -3608,16 +3608,16 @@ BoundingBox GetMeshBoundingBox(Mesh mesh)
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}
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// Compute mesh tangents
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// NOTE: To calculate mesh tangents and binormals we need mesh vertex positions and texture coordinates
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// Implementation based on: https://answers.unity.com/questions/7789/calculating-tangents-vector4.html
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void GenMeshTangents(Mesh *mesh)
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{
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if ((mesh->vertices == NULL) || (mesh->texcoords == NULL))
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// Check if input mesh data is useful
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if ((mesh == NULL) || (mesh->vertices == NULL) || (mesh->texcoords == NULL) || (mesh->normals == NULL))
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{
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TRACELOG(LOG_WARNING, "MESH: Tangents generation requires texcoord vertex attribute data");
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TRACELOG(LOG_WARNING, "MESH: Tangents generation requires vertices, texcoords and normals vertex attribute data");
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return;
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}
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// Allocate or reallocate tangents data
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if (mesh->tangents == NULL) mesh->tangents = (float *)RL_MALLOC(mesh->vertexCount*4*sizeof(float));
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else
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{
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@ -3625,26 +3625,51 @@ void GenMeshTangents(Mesh *mesh)
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mesh->tangents = (float *)RL_MALLOC(mesh->vertexCount*4*sizeof(float));
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}
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Vector3 *tan1 = (Vector3 *)RL_MALLOC(mesh->vertexCount*sizeof(Vector3));
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Vector3 *tan2 = (Vector3 *)RL_MALLOC(mesh->vertexCount*sizeof(Vector3));
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// Allocate temporary arrays for tangents calculation
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Vector3 *tan1 = (Vector3 *)RL_CALLOC(mesh->vertexCount, sizeof(Vector3));
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Vector3 *tan2 = (Vector3 *)RL_CALLOC(mesh->vertexCount, sizeof(Vector3));
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if (mesh->vertexCount % 3 != 0)
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if (tan1 == NULL || tan2 == NULL)
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{
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TRACELOG(LOG_WARNING, "MESH: vertexCount expected to be a multiple of 3. Expect uninitialized values.");
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TRACELOG(LOG_WARNING, "MESH: Failed to allocate temporary memory for tangent calculation");
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if (tan1) RL_FREE(tan1);
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if (tan2) RL_FREE(tan2);
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return;
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}
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for (int i = 0; i <= mesh->vertexCount - 3; i += 3)
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// Process all triangles of the mesh
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// 'triangleCount' must be always valid
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for (int t = 0; t < mesh->triangleCount; t++)
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{
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// Get triangle vertices
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Vector3 v1 = { mesh->vertices[(i + 0)*3 + 0], mesh->vertices[(i + 0)*3 + 1], mesh->vertices[(i + 0)*3 + 2] };
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Vector3 v2 = { mesh->vertices[(i + 1)*3 + 0], mesh->vertices[(i + 1)*3 + 1], mesh->vertices[(i + 1)*3 + 2] };
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Vector3 v3 = { mesh->vertices[(i + 2)*3 + 0], mesh->vertices[(i + 2)*3 + 1], mesh->vertices[(i + 2)*3 + 2] };
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// Get triangle vertex indices
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int i0, i1, i2;
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if (mesh->indices != NULL)
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{
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// Use indices if available
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i0 = mesh->indices[t*3 + 0];
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i1 = mesh->indices[t*3 + 1];
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i2 = mesh->indices[t*3 + 2];
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}
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else
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{
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// Sequential access for non-indexed mesh
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i0 = t*3 + 0;
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i1 = t*3 + 1;
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i2 = t*3 + 2;
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}
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// Get triangle vertices position
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Vector3 v1 = { mesh->vertices[i0*3 + 0], mesh->vertices[i0*3 + 1], mesh->vertices[i0*3 + 2] };
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Vector3 v2 = { mesh->vertices[i1*3 + 0], mesh->vertices[i1*3 + 1], mesh->vertices[i1*3 + 2] };
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Vector3 v3 = { mesh->vertices[i2*3 + 0], mesh->vertices[i2*3 + 1], mesh->vertices[i2*3 + 2] };
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// Get triangle texcoords
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Vector2 uv1 = { mesh->texcoords[(i + 0)*2 + 0], mesh->texcoords[(i + 0)*2 + 1] };
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Vector2 uv2 = { mesh->texcoords[(i + 1)*2 + 0], mesh->texcoords[(i + 1)*2 + 1] };
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Vector2 uv3 = { mesh->texcoords[(i + 2)*2 + 0], mesh->texcoords[(i + 2)*2 + 1] };
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Vector2 uv1 = { mesh->texcoords[i0*2 + 0], mesh->texcoords[i0*2 + 1] };
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Vector2 uv2 = { mesh->texcoords[i1*2 + 0], mesh->texcoords[i1*2 + 1] };
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Vector2 uv3 = { mesh->texcoords[i2*2 + 0], mesh->texcoords[i2*2 + 1] };
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// Calculate triangle edges
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float x1 = v2.x - v1.x;
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float y1 = v2.y - v1.y;
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float z1 = v2.z - v1.z;
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@ -3652,65 +3677,95 @@ void GenMeshTangents(Mesh *mesh)
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float y2 = v3.y - v1.y;
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float z2 = v3.z - v1.z;
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// Calculate texture coordinate differences
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float s1 = uv2.x - uv1.x;
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float t1 = uv2.y - uv1.y;
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float s2 = uv3.x - uv1.x;
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float t2 = uv3.y - uv1.y;
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// Calculate denominator and check for degenerate UV
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float div = s1*t2 - s2*t1;
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float r = (div == 0.0f)? 0.0f : 1.0f/div;
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float r = (fabsf(div) < 0.0001f)? 0.0f : 1.0f/div;
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// Calculate tangent and bitangent directions
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Vector3 sdir = { (t2*x1 - t1*x2)*r, (t2*y1 - t1*y2)*r, (t2*z1 - t1*z2)*r };
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Vector3 tdir = { (s1*x2 - s2*x1)*r, (s1*y2 - s2*y1)*r, (s1*z2 - s2*z1)*r };
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tan1[i + 0] = sdir;
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tan1[i + 1] = sdir;
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tan1[i + 2] = sdir;
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// Accumulate tangents and bitangents for each vertex of the triangle
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tan1[i0] = Vector3Add(tan1[i0], sdir);
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tan1[i1] = Vector3Add(tan1[i1], sdir);
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tan1[i2] = Vector3Add(tan1[i2], sdir);
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tan2[i + 0] = tdir;
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tan2[i + 1] = tdir;
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tan2[i + 2] = tdir;
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tan2[i0] = Vector3Add(tan2[i0], tdir);
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tan2[i1] = Vector3Add(tan2[i1], tdir);
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tan2[i2] = Vector3Add(tan2[i2], tdir);
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}
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// Compute tangents considering normals
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// Calculate final tangents for each vertex
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for (int i = 0; i < mesh->vertexCount; i++)
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{
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Vector3 normal = { mesh->normals[i*3 + 0], mesh->normals[i*3 + 1], mesh->normals[i*3 + 2] };
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Vector3 tangent = tan1[i];
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// TODO: Review, not sure if tangent computation is right, just used reference proposed maths...
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#if defined(COMPUTE_TANGENTS_METHOD_01)
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Vector3 tmp = Vector3Subtract(tangent, Vector3Scale(normal, Vector3DotProduct(normal, tangent)));
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tmp = Vector3Normalize(tmp);
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mesh->tangents[i*4 + 0] = tmp.x;
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mesh->tangents[i*4 + 1] = tmp.y;
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mesh->tangents[i*4 + 2] = tmp.z;
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mesh->tangents[i*4 + 3] = 1.0f;
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#else
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Vector3OrthoNormalize(&normal, &tangent);
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// Handle zero tangent (can happen with degenerate UVs)
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if (Vector3Length(tangent) < 0.0001f)
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{
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// Create a tangent perpendicular to the normal
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if (fabsf(normal.z) > 0.707f) tangent = (Vector3){ 1.0f, 0.0f, 0.0f };
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else tangent = Vector3Normalize((Vector3){ -normal.y, normal.x, 0.0f });
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mesh->tangents[i*4 + 0] = tangent.x;
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mesh->tangents[i*4 + 1] = tangent.y;
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mesh->tangents[i*4 + 2] = tangent.z;
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mesh->tangents[i*4 + 3] = (Vector3DotProduct(Vector3CrossProduct(normal, tangent), tan2[i]) < 0.0f)? -1.0f : 1.0f;
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#endif
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mesh->tangents[i*4 + 3] = 1.0f;
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continue;
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}
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// Gram-Schmidt orthogonalization to make tangent orthogonal to normal
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// T_prime = T - N * dot(N, T)
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Vector3 orthogonalized = Vector3Subtract(tangent, Vector3Scale(normal, Vector3DotProduct(normal, tangent)));
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// Handle cases where orthogonalized vector is too small
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if (Vector3Length(orthogonalized) < 0.0001f)
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{
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// Create a tangent perpendicular to the normal
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if (fabsf(normal.z) > 0.707f) orthogonalized = (Vector3){ 1.0f, 0.0f, 0.0f };
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else orthogonalized = Vector3Normalize((Vector3){ -normal.y, normal.x, 0.0f });
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}
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else
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{
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// Normalize the orthogonalized tangent
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orthogonalized = Vector3Normalize(orthogonalized);
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}
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// Store the calculated tangent
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mesh->tangents[i*4 + 0] = orthogonalized.x;
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mesh->tangents[i*4 + 1] = orthogonalized.y;
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mesh->tangents[i*4 + 2] = orthogonalized.z;
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// Calculate the handedness (w component)
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mesh->tangents[i*4 + 3] = (Vector3DotProduct(Vector3CrossProduct(normal, orthogonalized), tan2[i]) < 0.0f)? -1.0f : 1.0f;
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}
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// Free temporary arrays
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RL_FREE(tan1);
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RL_FREE(tan2);
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// Update vertex buffers if available
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if (mesh->vboId != NULL)
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{
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if (mesh->vboId[SHADER_LOC_VERTEX_TANGENT] != 0)
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{
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// Update existing vertex buffer
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// Update existing tangent vertex buffer
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rlUpdateVertexBuffer(mesh->vboId[SHADER_LOC_VERTEX_TANGENT], mesh->tangents, mesh->vertexCount*4*sizeof(float), 0);
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}
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else
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{
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// Load a new tangent attributes buffer
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// Create new tangent vertex buffer
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mesh->vboId[SHADER_LOC_VERTEX_TANGENT] = rlLoadVertexBuffer(mesh->tangents, mesh->vertexCount*4*sizeof(float), false);
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}
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// Set up vertex attributes for shader
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rlEnableVertexArray(mesh->vaoId);
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rlSetVertexAttribute(RL_DEFAULT_SHADER_ATTRIB_LOCATION_TANGENT, 4, RL_FLOAT, 0, 0, 0);
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rlEnableVertexAttribute(RL_DEFAULT_SHADER_ATTRIB_LOCATION_TANGENT);
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