Handle sharp edges in vertex buffer

QTProject/subdivision-vertex.compute

@@ -22,30 +22,61 @@ layout(std430, binding=2) readonly buffer VertexOffsets {
     unsigned int offsets[];
 };
 
-layout(std430, binding=3) writeonly buffer Output {
+layout(std430, binding=3) readonly buffer VertexSharpness {
+    unsigned int sharpness[];
+};
+
+layout(std430, binding=4) writeonly buffer Output {
     Vertex new_vertices[];
 };
 
-layout(std430, binding=4) readonly buffer OutputOffset {
+layout(std430, binding=5) readonly buffer OutputOffset {
     unsigned int output_offset;
 };
 
 void main(){
-    unsigned int size = offsets[gl_GlobalInvocationID.x + 1] - offsets[gl_GlobalInvocationID.x];
+    unsigned int offset = offsets[gl_GlobalInvocationID.x];
+    unsigned int size = offsets[gl_GlobalInvocationID.x + 1] - offset;
 
     new_vertices[output_offset + gl_GlobalInvocationID.x].uv = vec2(0.0f, 0.0f);
+    new_vertices[output_offset + gl_GlobalInvocationID.x].norm = vec3(0.0f, 0.0f, 0.0f);
 
     // FIXME: size or size - 1?
     float t = 3.0f/8.0f + 2.0f/8.0f * cos(2.0f * M_PI / (float(size) - 1.0f));
     float alpha = 5.0f/8.0f - t * t;
 
-    vec3 pos = vec3(0.0f, 0.0f, 0.0f);
-    vec3 norm = vec3(0.0f, 0.0f, 0.0f);
+    unsigned int sharp = 0;
+    unsigned int sharp_a = 0;
+    unsigned int sharp_b = 0;
     for (unsigned int i = 1; i < size; i++) {
-        pos += vertices[indices[offsets[gl_GlobalInvocationID.x] + i]].pos;
-        norm += vertices[indices[offsets[gl_GlobalInvocationID.x] + i]].norm;
+        if (sharpness[offset + i] > 0) {
+            sharp++;
+            if (sharp == 1) {
+                sharp_a = i;
+            } else if (sharp == 2) {
+                sharp_b = i;
+            }
+        }
+    }
+
+    vec3 pos = vec3(0.0f, 0.0f, 0.0f);
+    switch (sharp) {
+        case 0:
+        case 1:
+            for (unsigned int i = 1; i < size; i++) {
+                pos += vertices[indices[offset + i]].pos;
+            }
+
+            pos = (1.0f - alpha) * vertices[indices[offset]].pos + alpha / (float(size) - 1.0f) * pos;
+            break;
+
+        case 2:
+            pos = (6.0f * vertices[indices[offset]].pos + vertices[indices[offset + sharp_a]].pos + vertices[indices[offset + sharp_b]].pos) / 8.0f;
+            break;
+
+        default:
+            pos = vertices[indices[offset]].pos;
     }
 
-    new_vertices[output_offset + gl_GlobalInvocationID.x].pos = (1.0f - alpha) * vertices[indices[offsets[gl_GlobalInvocationID.x]]].pos + alpha / (float(size) - 1.0f) * pos;
-    new_vertices[output_offset + gl_GlobalInvocationID.x].norm = normalize((1.0f - alpha) * vertices[indices[offsets[gl_GlobalInvocationID.x]]].norm + alpha / (float(size) - 1.0f) * norm);
+    new_vertices[output_offset + gl_GlobalInvocationID.x].pos = pos;
 }

QTProject/subdivision.cpp

@@ -182,6 +182,10 @@ Subdivision::Tables Subdivision::precomputeTables(Input input) {
     qCDebug(log_timing) << "precomputeVertexTable:" << formatTimeMeasurement(subTimer.elapsed());
 
     subTimer.restart();
+    precomputeSharpnessEdges(input, tables);
+    qCDebug(log_timing) << "precomputeSharpnessEdges:" << formatTimeMeasurement(subTimer.elapsed());
+
+    subTimer.restart();
     updateIndexBuffer(tables.index_buffer, modified_vertices);
     updateIndexBuffer(tables.extra_triangles, modified_vertices);
     qCDebug(log_timing) << "updateIndexBuffer:" << formatTimeMeasurement(subTimer.elapsed());
@@ -738,6 +742,27 @@ void Subdivision::updateSharpEdges(const QMap<Edge,unsigned int> &sharp_edges_ol
     }
 }
 
+void Subdivision::precomputeSharpnessEdges(const Input &input, Tables &tables) {
+    for (int i = 0; i < tables.vertex_offsets.length() - 1; i++) {
+        int size = tables.vertex_offsets[i+1] - tables.vertex_offsets[i];
+        GLuint center = tables.vertex_indices[tables.vertex_offsets[i]];
+        tables.vertex_sharpness.push_back(0); // vertex to itself isn't used
+        for (int j = 1; j < size; j++) {
+            GLuint neighbor = tables.vertex_indices[tables.vertex_offsets[i] + j];
+            bool sharp = false;
+            Edge e = { center, neighbor };
+            if (input.sharp_edges.value(e, 0) > 0) {
+                sharp = true;
+            }
+            e = { neighbor, center };
+            if (input.sharp_edges.value(e, 0) > 0) {
+                sharp = true;
+            }
+            tables.vertex_sharpness.push_back((GLuint) (sharp ? 1 : 0));
+        }
+    }
+}
+
 void Subdivision::splitRegular(Mesh *mesh) {
     QTime totalTimer;
     totalTimer.start();
@@ -965,6 +990,12 @@ Subdivision::Result Subdivision::runShader(Input input, Tables &tables) {
     f->glBindBuffer(GL_SHADER_STORAGE_BUFFER, vertex_offsets_handle);
     f->glBufferData(GL_SHADER_STORAGE_BUFFER, tables.vertex_offsets.size() * sizeof(GLuint), tables.vertex_offsets.data(), GL_DYNAMIC_DRAW);
 
+    // Create an input buffer for the vertex sharpnesses
+    GLuint vertex_sharpness_handle;
+    f->glGenBuffers(1, &vertex_sharpness_handle);
+    f->glBindBuffer(GL_SHADER_STORAGE_BUFFER, vertex_sharpness_handle);
+    f->glBufferData(GL_SHADER_STORAGE_BUFFER, tables.vertex_sharpness.size() * sizeof(GLuint), tables.vertex_sharpness.data(), GL_DYNAMIC_DRAW);
+
     // Create an input buffer for the edge indices
     GLuint edge_indices_handle;
     f->glGenBuffers(1, &edge_indices_handle);
@@ -1030,7 +1061,7 @@ Subdivision::Result Subdivision::runShader(Input input, Tables &tables) {
     offset_buffer = (GLuint *) f->glMapBuffer(GL_SHADER_STORAGE_BUFFER, GL_WRITE_ONLY);
     *offset_buffer = input.vertex_buffer.size() + tables.edge_indices.size() / 4;
     f->glUnmapBuffer(GL_SHADER_STORAGE_BUFFER);
-    runVertexShader(tables.vertex_offsets.size() - 1, input.vb_handle, vertex_indices_handle, vertex_offsets_handle, output_handle, offset_handle);
+    runVertexShader(tables.vertex_offsets.size() - 1, input.vb_handle, vertex_indices_handle, vertex_offsets_handle, vertex_sharpness_handle, output_handle, offset_handle);
     int vertexTime = timer.elapsed();
 
     timer.restart();
@@ -1074,14 +1105,15 @@ void Subdivision::runCopyShader(GLuint size, GLuint vb_in, GLuint vb_out) {
     copyShader->release();
 }
 
-void Subdivision::runVertexShader(GLuint size, GLuint vb_handle, GLuint vertex_indices_handle, GLuint vertex_offsets_handle, GLuint output_handle, GLuint offset_handle) {
+void Subdivision::runVertexShader(GLuint size, GLuint vb_handle, GLuint vertex_indices_handle, GLuint vertex_offsets_handle, GLuint vertex_sharpness_handle, GLuint output_handle, GLuint offset_handle) {
     vertexShader->bind();
 
     f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 0, vb_handle);
     f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 1, vertex_indices_handle);
     f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 2, vertex_offsets_handle);
-    f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 3, output_handle);
-    f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 4, offset_handle);
+    f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 3, vertex_sharpness_handle);
+    f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 4, output_handle);
+    f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 5, offset_handle);
 
     // Run the shader
     f->glDispatchCompute(size, 1, 1);
@@ -1095,6 +1127,7 @@ void Subdivision::runVertexShader(GLuint size, GLuint vb_handle, GLuint vertex_i
     f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 2, 0);
     f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 3, 0);
     f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 4, 0);
+    f->glBindBufferBase(GL_SHADER_STORAGE_BUFFER, 5, 0);
 
     vertexShader->release();
 }

QTProject/subdivision.h

@@ -34,6 +34,7 @@ private:
         QMap<Edge,unsigned int> sharp_edges;
         QVector<GLuint> vertex_indices;
         QVector<GLuint> vertex_offsets;
+        QVector<GLuint> vertex_sharpness;
         QVector<GLuint> index_buffer;
         QVector<GLuint> patch_index_regular;
         QVector<GLuint> extra_triangles;
@@ -79,10 +80,11 @@ private:
                           QMap<Edge,unsigned int> &sharp_edges_new,
                                        const QMap<unsigned int, unsigned int>& old_vertex_to_new_vertex,
                                        const QMap<Edge,unsigned int> &old_edge_to_new_vertex);
+    void precomputeSharpnessEdges(const Input &input, Tables &tables);
     void findRegular(QVector<Triangle> triangles, QMap<Triangle, Triangle::Neighbors> neighbors, QVector<Triangle> &regular, QVector<Triangle> &irregular);
     Result runShader(Input input, Tables &tables);
     void runCopyShader(GLuint size, GLuint vb_in, GLuint vb_out);
-    void runVertexShader(GLuint size, GLuint vb_handle, GLuint vertex_indices_handle, GLuint vertex_offsets_handle, GLuint output_handle, GLuint offset_handle);
+    void runVertexShader(GLuint size, GLuint vb_handle, GLuint vertex_indices_handle, GLuint vertex_offsets_handle, GLuint vertex_sharpness_handle, GLuint output_handle, GLuint offset_handle);
     void runEdgeShader(GLuint size, GLuint vb_handle, GLuint edge_indices_handle, GLuint edge_sharpness_handle, GLuint output_handle, GLuint offset_handle);
     void updateIrregularForDraw(const QVector<Triangle> &triangles, QMap<Triangle, Triangle::Neighbors> &neighbors, Result &result);
     bool containsVertex(QVector<Vertex> &vertices, Vertex vertex);