Merge pull request #3269 from ey6es/metavoxels

Script access for heightfield heights, ray intersection against heightfields, basic color and height brush tools.

interface/resources/shaders/metavoxel_heightfield_cursor.frag

@@ -0,0 +1,32 @@
+#version 120
+
+//
+//  metavoxel_heightfield_cursor.frag
+//  fragment shader
+//
+//  Created by Andrzej Kapolka on 8/7/14.
+//  Copyright 2014 High Fidelity, Inc.
+//
+//  Distributed under the Apache License, Version 2.0.
+//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
+//
+
+// the inner radius of the outline, squared
+const float SQUARED_OUTLINE_INNER_RADIUS = 0.81;
+
+// the outer radius of the outline, squared
+const float SQUARED_OUTLINE_OUTER_RADIUS = 1.0;
+
+// the inner radius of the inset, squared
+const float SQUARED_INSET_INNER_RADIUS = 0.855625;
+
+// the outer radius of the inset, squared
+const float SQUARED_INSET_OUTER_RADIUS = 0.950625;
+
+void main(void) {
+    // use the distance to compute the ring color, then multiply it by the varying color
+    float squaredDistance = dot(gl_TexCoord[0].st, gl_TexCoord[0].st);
+    float alpha = step(SQUARED_OUTLINE_INNER_RADIUS, squaredDistance) * step(squaredDistance, SQUARED_OUTLINE_OUTER_RADIUS);
+    float white = step(SQUARED_INSET_INNER_RADIUS, squaredDistance) * step(squaredDistance, SQUARED_INSET_OUTER_RADIUS);
+    gl_FragColor = gl_Color * vec4(white, white, white, alpha);
+}

interface/resources/shaders/metavoxel_heightfield_cursor.vert

@@ -0,0 +1,31 @@
+#version 120
+
+//
+//  metavoxel_heighfield_cursor.vert
+//  vertex shader
+//
+//  Created by Andrzej Kapolka on 8/7/14.
+//  Copyright 2014 High Fidelity, Inc.
+//
+//  Distributed under the Apache License, Version 2.0.
+//  See the accompanying file LICENSE or http://www.apache.org/licenses/LICENSE-2.0.html
+//
+
+// the height texture
+uniform sampler2D heightMap;
+
+// the distance between height points in texture space
+uniform float heightScale;
+
+void main(void) {
+    // compute the view space coordinates
+    float height = texture2D(heightMap, gl_MultiTexCoord0.st).r;
+    vec4 viewPosition = gl_ModelViewMatrix * (gl_Vertex + vec4(0.0, height, 0.0, 0.0));
+    gl_Position = gl_ProjectionMatrix * viewPosition;
+
+    // generate the texture coordinates from the view position
+    gl_TexCoord[0] = vec4(dot(viewPosition, gl_EyePlaneS[4]), dot(viewPosition, gl_EyePlaneT[4]), 0.0, 1.0);
+    
+    // the zero height should be invisible
+    gl_FrontColor = vec4(1.0, 1.0, 1.0, 1.0 - step(height, 0.0));
+}

interface/src/MetavoxelSystem.cpp

@@ -118,6 +118,73 @@ void MetavoxelSystem::render() {
     guideToAugmented(renderVisitor);
 }
 
+class HeightfieldCursorRenderVisitor : public MetavoxelVisitor {
+public:
+    
+    HeightfieldCursorRenderVisitor(const MetavoxelLOD& lod, const Box& bounds);
+    
+    virtual int visit(MetavoxelInfo& info);
+
+private:
+    
+    Box _bounds;
+};
+
+HeightfieldCursorRenderVisitor::HeightfieldCursorRenderVisitor(const MetavoxelLOD& lod, const Box& bounds) :
+    MetavoxelVisitor(QVector<AttributePointer>() <<
+        Application::getInstance()->getMetavoxels()->getHeightfieldBufferAttribute(), QVector<AttributePointer>(), lod),
+    _bounds(bounds) {
+}
+
+int HeightfieldCursorRenderVisitor::visit(MetavoxelInfo& info) {
+    if (!info.getBounds().intersects(_bounds)) {
+        return STOP_RECURSION;
+    }
+    if (!info.isLeaf) {
+        return DEFAULT_ORDER;
+    }
+    BufferDataPointer buffer = info.inputValues.at(0).getInlineValue<BufferDataPointer>();
+    if (buffer) {
+        buffer->render(true);
+    }
+    return STOP_RECURSION;
+}
+
+void MetavoxelSystem::renderHeightfieldCursor(const glm::vec3& position, float radius) {
+    glDepthFunc(GL_LEQUAL);
+    glEnable(GL_CULL_FACE);
+    glEnable(GL_POLYGON_OFFSET_FILL);
+    glPolygonOffset(-1.0f, -1.0f);
+    
+    glColor4f(1.0f, 1.0f, 1.0f, 1.0f);
+    
+    glEnableClientState(GL_VERTEX_ARRAY);
+    glEnableClientState(GL_TEXTURE_COORD_ARRAY);
+    
+    DefaultMetavoxelRendererImplementation::getHeightfieldCursorProgram().bind();
+    
+    glActiveTexture(GL_TEXTURE4);
+    float scale = 1.0f / radius;
+    glm::vec4 sCoefficients(scale, 0.0f, 0.0f, -scale * position.x);
+    glm::vec4 tCoefficients(0.0f, 0.0f, scale, -scale * position.z);
+    glTexGenfv(GL_S, GL_EYE_PLANE, (const GLfloat*)&sCoefficients);
+    glTexGenfv(GL_T, GL_EYE_PLANE, (const GLfloat*)&tCoefficients);
+    glActiveTexture(GL_TEXTURE0);
+    
+    glm::vec3 extents(radius, radius, radius);
+    HeightfieldCursorRenderVisitor visitor(getLOD(), Box(position - extents, position + extents));
+    guideToAugmented(visitor);
+    
+    DefaultMetavoxelRendererImplementation::getHeightfieldCursorProgram().release();
+    
+    glDisableClientState(GL_TEXTURE_COORD_ARRAY);
+    glDisableClientState(GL_VERTEX_ARRAY);
+    
+    glDisable(GL_POLYGON_OFFSET_FILL);
+    glDisable(GL_CULL_FACE);
+    glDepthFunc(GL_LESS);
+}
+
 void MetavoxelSystem::deleteTextures(int heightID, int colorID) {
     glDeleteTextures(1, (GLuint*)&heightID);
     glDeleteTextures(1, (GLuint*)&colorID);
@@ -239,7 +306,7 @@ PointBuffer::PointBuffer(const BufferPointVector& points) :
     _points(points) {
 }
 
-void PointBuffer::render() {
+void PointBuffer::render(bool cursor) {
     // initialize buffer, etc. on first render
     if (!_buffer.isCreated()) {
         _buffer.setUsagePattern(QOpenGLBuffer::StaticDraw);
@@ -294,7 +361,7 @@ public:
     glm::vec3 vertex;
 };
 
-void HeightfieldBuffer::render() {
+void HeightfieldBuffer::render(bool cursor) {
     // initialize textures, etc. on first render
     if (_heightTextureID == 0) {
         glGenTextures(1, &_heightTextureID);
@@ -385,17 +452,24 @@ void HeightfieldBuffer::render() {
     
     glBindTexture(GL_TEXTURE_2D, _heightTextureID);
     
-    glActiveTexture(GL_TEXTURE1);
-    glBindTexture(GL_TEXTURE_2D, _colorTextureID);
+    int heightScaleLocation;
+    if (cursor) {
+        heightScaleLocation = DefaultMetavoxelRendererImplementation::getCursorHeightScaleLocation();
+    } else {
+        heightScaleLocation = DefaultMetavoxelRendererImplementation::getHeightScaleLocation();
+        glActiveTexture(GL_TEXTURE1);
+        glBindTexture(GL_TEXTURE_2D, _colorTextureID);
+    }
     
-    DefaultMetavoxelRendererImplementation::getHeightfieldProgram().setUniformValue(
-        DefaultMetavoxelRendererImplementation::getHeightScaleLocation(), 1.0f / _heightSize);
+    DefaultMetavoxelRendererImplementation::getHeightfieldProgram().setUniformValue(heightScaleLocation, 1.0f / _heightSize);
         
     glDrawRangeElements(GL_QUADS, 0, vertexCount - 1, indexCount, GL_UNSIGNED_INT, 0);
     
-    glBindTexture(GL_TEXTURE_2D, 0);
+    if (!cursor) {
+        glBindTexture(GL_TEXTURE_2D, 0);
+        glActiveTexture(GL_TEXTURE0); 
+    }
     
-    glActiveTexture(GL_TEXTURE0); 
     glBindTexture(GL_TEXTURE_2D, 0);
     
     glPopMatrix();
@@ -475,6 +549,17 @@ void DefaultMetavoxelRendererImplementation::init() {
         _heightfieldProgram.setUniformValue("diffuseMap", 1);
         _heightScaleLocation = _heightfieldProgram.uniformLocation("heightScale");
         _heightfieldProgram.release();
+        
+        _heightfieldCursorProgram.addShaderFromSourceFile(QGLShader::Vertex, Application::resourcesPath() +
+            "shaders/metavoxel_heightfield_cursor.vert");
+        _heightfieldCursorProgram.addShaderFromSourceFile(QGLShader::Fragment, Application::resourcesPath() +
+            "shaders/metavoxel_heightfield_cursor.frag");
+        _heightfieldCursorProgram.link();
+        
+        _heightfieldCursorProgram.bind();
+        _heightfieldCursorProgram.setUniformValue("heightMap", 0);
+        _cursorHeightScaleLocation = _heightfieldCursorProgram.uniformLocation("heightScale");
+        _heightfieldCursorProgram.release();
     }
 }
 
@@ -771,6 +856,8 @@ ProgramObject DefaultMetavoxelRendererImplementation::_pointProgram;
 int DefaultMetavoxelRendererImplementation::_pointScaleLocation;
 ProgramObject DefaultMetavoxelRendererImplementation::_heightfieldProgram;
 int DefaultMetavoxelRendererImplementation::_heightScaleLocation;
+ProgramObject DefaultMetavoxelRendererImplementation::_heightfieldCursorProgram;
+int DefaultMetavoxelRendererImplementation::_cursorHeightScaleLocation;
 
 static void enableClipPlane(GLenum plane, float x, float y, float z, float w) {
     GLdouble coefficients[] = { x, y, z, w };

interface/src/MetavoxelSystem.h

@@ -43,6 +43,8 @@ public:
     void simulate(float deltaTime);
     void render();
 
+    void renderHeightfieldCursor(const glm::vec3& position, float radius);
+
     Q_INVOKABLE void deleteTextures(int heightID, int colorID);
 
 protected:
@@ -105,7 +107,7 @@ public:
     
     virtual ~BufferData();
 
-    virtual void render() = 0;
+    virtual void render(bool cursor = false) = 0;
 };
 
 typedef QExplicitlySharedDataPointer<BufferData> BufferDataPointer;
@@ -116,7 +118,7 @@ public:
 
     PointBuffer(const BufferPointVector& points);
 
-    virtual void render();
+    virtual void render(bool cursor = false);
 
 private:
     
@@ -140,7 +142,7 @@ public:
     const QByteArray& getHeight() const { return _height; }
     const QByteArray& getColor() const { return _color; }
     
-    virtual void render();
+    virtual void render(bool cursor = false);
 
 private:
     
@@ -193,6 +195,9 @@ public:
     static ProgramObject& getHeightfieldProgram() { return _heightfieldProgram; }
     static int getHeightScaleLocation() { return _heightScaleLocation; }
 
+    static ProgramObject& getHeightfieldCursorProgram() { return _heightfieldCursorProgram; }
+    static int getCursorHeightScaleLocation() { return _cursorHeightScaleLocation; }
+    
     Q_INVOKABLE DefaultMetavoxelRendererImplementation();
     
     virtual void augment(MetavoxelData& data, const MetavoxelData& previous, MetavoxelInfo& info, const MetavoxelLOD& lod);
@@ -206,6 +211,9 @@ private:
     
     static ProgramObject _heightfieldProgram;
     static int _heightScaleLocation;
+    
+    static ProgramObject _heightfieldCursorProgram;
+    static int _cursorHeightScaleLocation;
 };
 
 /// Base class for spanner renderers; provides clipping.

interface/src/ui/MetavoxelEditor.cpp

@@ -118,6 +118,8 @@ MetavoxelEditor::MetavoxelEditor() :
     addTool(new SetSpannerTool(this));
     addTool(new ImportHeightfieldTool(this));
     addTool(new EraseHeightfieldTool(this));
+    addTool(new HeightfieldHeightBrushTool(this));
+    addTool(new HeightfieldColorBrushTool(this));
     
     updateAttributes();
     
@@ -1080,3 +1082,72 @@ void EraseHeightfieldTool::apply() {
     message.edit = QVariant::fromValue(edit);
     Application::getInstance()->getMetavoxels()->applyEdit(message, true);
 }
+
+HeightfieldBrushTool::HeightfieldBrushTool(MetavoxelEditor* editor, const QString& name) :
+    MetavoxelTool(editor, name, false) {
+    
+    QWidget* widget = new QWidget();
+    widget->setLayout(_form = new QFormLayout());
+    layout()->addWidget(widget);
+    
+    _form->addRow("Radius:", _radius = new QDoubleSpinBox());
+    _radius->setSingleStep(0.01);
+    _radius->setMaximum(FLT_MAX);
+    _radius->setValue(1.0);
+}
+
+void HeightfieldBrushTool::render() {
+    if (Application::getInstance()->isMouseHidden()) {
+        return;
+    }
+    
+    // find the intersection with the heightfield
+    glm::vec3 origin = Application::getInstance()->getMouseRayOrigin();
+    glm::vec3 direction = Application::getInstance()->getMouseRayDirection();
+    
+    float distance;
+    if (!Application::getInstance()->getMetavoxels()->findFirstRayHeightfieldIntersection(origin, direction, distance)) {
+        return;
+    }
+    Application::getInstance()->getMetavoxels()->renderHeightfieldCursor(
+        _position = origin + distance * direction, _radius->value());
+}
+
+bool HeightfieldBrushTool::eventFilter(QObject* watched, QEvent* event) {
+    if (event->type() == QEvent::Wheel) {
+        float angle = static_cast<QWheelEvent*>(event)->angleDelta().y();
+        const float ANGLE_SCALE = 1.0f / 1000.0f;
+        _radius->setValue(_radius->value() * glm::pow(2.0f, angle * ANGLE_SCALE));
+        return true;
+    
+    } else if (event->type() == QEvent::MouseButtonPress) {
+        MetavoxelEditMessage message = { createEdit(static_cast<QMouseEvent*>(event)->button() == Qt::RightButton) };
+        Application::getInstance()->getMetavoxels()->applyEdit(message, true);
+        return true;
+    }
+    return false;
+}
+
+HeightfieldHeightBrushTool::HeightfieldHeightBrushTool(MetavoxelEditor* editor) :
+    HeightfieldBrushTool(editor, "Height Brush") {
+    
+    _form->addRow("Height:", _height = new QDoubleSpinBox());
+    _height->setMinimum(-FLT_MAX);
+    _height->setMaximum(FLT_MAX);
+    _height->setValue(1.0);
+}
+
+QVariant HeightfieldHeightBrushTool::createEdit(bool alternate) {
+    return QVariant::fromValue(PaintHeightfieldHeightEdit(_position, _radius->value(),
+        alternate ? -_height->value() : _height->value()));
+}
+
+HeightfieldColorBrushTool::HeightfieldColorBrushTool(MetavoxelEditor* editor) :
+    HeightfieldBrushTool(editor, "Color Brush") {
+    
+    _form->addRow("Color:", _color = new QColorEditor(this));
+}
+
+QVariant HeightfieldColorBrushTool::createEdit(bool alternate) {
+    return QVariant::fromValue(PaintHeightfieldColorEdit(_position, _radius->value(), _color->getColor()));
+}

interface/src/ui/MetavoxelEditor.h

@@ -18,6 +18,7 @@
 #include "MetavoxelSystem.h"
 #include "renderer/ProgramObject.h"
 
+class QColorEditor;
 class QComboBox;
 class QDoubleSpinBox;
 class QGroupBox;
@@ -282,7 +283,7 @@ private:
     HeightfieldPreview _preview;
 };
 
-// Allows clearing heighfield blocks.
+/// Allows clearing heighfield blocks.
 class EraseHeightfieldTool : public HeightfieldTool {
     Q_OBJECT
 
@@ -302,4 +303,60 @@ private:
     QSpinBox* _length;
 };
 
+/// Base class for tools that allow painting on heightfields.
+class HeightfieldBrushTool : public MetavoxelTool {
+    Q_OBJECT
+
+public:
+    
+    HeightfieldBrushTool(MetavoxelEditor* editor, const QString& name);
+    
+    virtual void render();
+
+    virtual bool eventFilter(QObject* watched, QEvent* event);
+    
+protected:
+    
+    virtual QVariant createEdit(bool alternate) = 0;
+    
+    QFormLayout* _form;
+    QDoubleSpinBox* _radius;
+    
+    glm::vec3 _position;
+};
+
+/// Allows raising or lowering parts of the heightfield.
+class HeightfieldHeightBrushTool : public HeightfieldBrushTool {
+    Q_OBJECT
+
+public:
+    
+    HeightfieldHeightBrushTool(MetavoxelEditor* editor);
+    
+protected:
+    
+    virtual QVariant createEdit(bool alternate);
+    
+private:
+    
+    QDoubleSpinBox* _height;
+};
+
+/// Allows coloring parts of the heightfield.
+class HeightfieldColorBrushTool : public HeightfieldBrushTool {
+    Q_OBJECT
+
+public:
+    
+    HeightfieldColorBrushTool(MetavoxelEditor* editor);
+
+protected:
+    
+    virtual QVariant createEdit(bool alternate);
+    
+private:
+    
+    QColorEditor* _color;
+};
+
 #endif // hifi_MetavoxelEditor_h

libraries/metavoxels/src/MetavoxelClientManager.cpp

@@ -61,6 +61,180 @@ SharedObjectPointer MetavoxelClientManager::findFirstRaySpannerIntersection(cons
     return closestSpanner;
 }
 
+class RayHeightfieldIntersectionVisitor : public RayIntersectionVisitor {
+public:
+    
+    float intersectionDistance;
+    
+    RayHeightfieldIntersectionVisitor(const glm::vec3& origin, const glm::vec3& direction, const MetavoxelLOD& lod);
+    
+    virtual int visit(MetavoxelInfo& info, float distance);
+};
+
+RayHeightfieldIntersectionVisitor::RayHeightfieldIntersectionVisitor(const glm::vec3& origin,
+        const glm::vec3& direction, const MetavoxelLOD& lod) :
+    RayIntersectionVisitor(origin, direction, QVector<AttributePointer>() <<
+        AttributeRegistry::getInstance()->getHeightfieldAttribute(), QVector<AttributePointer>(), lod),
+    intersectionDistance(FLT_MAX) {
+}
+
+static const float EIGHT_BIT_MAXIMUM_RECIPROCAL = 1.0f / 255.0f;
+
+int RayHeightfieldIntersectionVisitor::visit(MetavoxelInfo& info, float distance) {
+    if (!info.isLeaf) {
+        return _order;
+    }
+    HeightfieldDataPointer pointer = info.inputValues.at(0).getInlineValue<HeightfieldDataPointer>();
+    if (!pointer) {
+        return STOP_RECURSION;
+    }
+    const QByteArray& contents = pointer->getContents();
+    const uchar* src = (const uchar*)contents.constData();
+    int size = glm::sqrt((float)contents.size());
+    int highest = size - 1;
+    float heightScale = highest * EIGHT_BIT_MAXIMUM_RECIPROCAL;
+    
+    // find the initial location in heightfield coordinates
+    glm::vec3 entry = (_origin + distance * _direction - info.minimum) * (float)highest / info.size;
+    glm::vec3 floors = glm::floor(entry);
+    glm::vec3 ceils = glm::ceil(entry);
+    if (floors.x == ceils.x) {
+        if (_direction.x > 0.0f) {
+            ceils.x += 1.0f;
+        } else {
+            floors.x -= 1.0f;
+        } 
+    }
+    if (floors.z == ceils.z) {
+        if (_direction.z > 0.0f) {
+            ceils.z += 1.0f;
+        } else {
+            floors.z -= 1.0f;
+        }
+    }
+    
+    bool withinBounds = true;
+    float accumulatedDistance = 0.0f;
+    while (withinBounds) {
+        // find the heights at the corners of the current cell
+        int floorX = qMin(qMax((int)floors.x, 0), highest);
+        int floorZ = qMin(qMax((int)floors.z, 0), highest);
+        int ceilX = qMin(qMax((int)ceils.x, 0), highest);
+        int ceilZ = qMin(qMax((int)ceils.z, 0), highest);
+        float upperLeft = src[floorZ * size + floorX] * heightScale;
+        float upperRight = src[floorZ * size + ceilX] * heightScale;
+        float lowerLeft = src[ceilZ * size + floorX] * heightScale;
+        float lowerRight = src[ceilZ * size + ceilX] * heightScale;
+        
+        // find the distance to the next x coordinate
+        float xDistance = FLT_MAX;
+        if (_direction.x > 0.0f) {
+            xDistance = (ceils.x - entry.x) / _direction.x;
+        } else if (_direction.x < 0.0f) {
+            xDistance = (floors.x - entry.x) / _direction.x;
+        }
+        
+        // and the distance to the next z coordinate
+        float zDistance = FLT_MAX;
+        if (_direction.z > 0.0f) {
+            zDistance = (ceils.z - entry.z) / _direction.z;
+        } else if (_direction.z < 0.0f) {
+            zDistance = (floors.z - entry.z) / _direction.z;
+        }
+        
+        // the exit distance is the lower of those two
+        float exitDistance = qMin(xDistance, zDistance);
+        glm::vec3 exit, nextFloors = floors, nextCeils = ceils;
+        if (exitDistance == FLT_MAX) {
+            if (_direction.y > 0.0f) {
+                return SHORT_CIRCUIT; // line points upwards; no collisions possible
+            }    
+            withinBounds = false; // line points downwards; check this cell only
+            
+        } else {
+            // find the exit point and the next cell, and determine whether it's still within the bounds
+            exit = entry + exitDistance * _direction;
+            withinBounds = (exit.y >= 0.0f && exit.y <= highest);
+            if (exitDistance == xDistance) {
+                if (_direction.x > 0.0f) {
+                    nextFloors.x += 1.0f;
+                    withinBounds &= (nextCeils.x += 1.0f) <= highest;
+                } else {
+                    withinBounds &= (nextFloors.x -= 1.0f) >= 0.0f;
+                    nextCeils.x -= 1.0f;
+                }
+            }
+            if (exitDistance == zDistance) {
+                if (_direction.z > 0.0f) {
+                    nextFloors.z += 1.0f;
+                    withinBounds &= (nextCeils.z += 1.0f) <= highest;
+                } else {
+                    withinBounds &= (nextFloors.z -= 1.0f) >= 0.0f;
+                    nextCeils.z -= 1.0f;
+                }
+            }
+            // check the vertical range of the ray against the ranges of the cell heights
+            if (qMin(entry.y, exit.y) > qMax(qMax(upperLeft, upperRight), qMax(lowerLeft, lowerRight)) ||
+                    qMax(entry.y, exit.y) < qMin(qMin(upperLeft, upperRight), qMin(lowerLeft, lowerRight))) {
+                entry = exit;
+                floors = nextFloors;
+                ceils = nextCeils;
+                accumulatedDistance += exitDistance;
+                continue;
+            } 
+        }
+        // having passed the bounds check, we must check against the planes
+        glm::vec3 relativeEntry = entry - glm::vec3(floors.x, upperLeft, floors.z);
+        
+        // first check the triangle including the Z+ segment
+        glm::vec3 lowerNormal(lowerLeft - lowerRight, 1.0f, upperLeft - lowerLeft);
+        float lowerProduct = glm::dot(lowerNormal, _direction);
+        if (lowerProduct < 0.0f) {
+            float planeDistance = -glm::dot(lowerNormal, relativeEntry) / lowerProduct;
+            glm::vec3 intersection = relativeEntry + planeDistance * _direction;
+            if (intersection.x >= 0.0f && intersection.x <= 1.0f && intersection.z >= 0.0f && intersection.z <= 1.0f &&
+                    intersection.z >= intersection.x) {
+                intersectionDistance = qMin(intersectionDistance, distance +
+                    (accumulatedDistance + planeDistance) * (info.size / highest));
+                return SHORT_CIRCUIT;
+            }
+        }
+        
+        // then the one with the X+ segment
+        glm::vec3 upperNormal(upperLeft - upperRight, 1.0f, upperRight - lowerRight);
+        float upperProduct = glm::dot(upperNormal, _direction);
+        if (upperProduct < 0.0f) {
+            float planeDistance = -glm::dot(upperNormal, relativeEntry) / upperProduct;
+            glm::vec3 intersection = relativeEntry + planeDistance * _direction;
+            if (intersection.x >= 0.0f && intersection.x <= 1.0f && intersection.z >= 0.0f && intersection.z <= 1.0f &&
+                    intersection.x >= intersection.z) {
+                intersectionDistance = qMin(intersectionDistance, distance +
+                    (accumulatedDistance + planeDistance) * (info.size / highest));
+                return SHORT_CIRCUIT;
+            }
+        }
+        
+        // no joy; continue on our way
+        entry = exit;
+        floors = nextFloors;
+        ceils = nextCeils;
+        accumulatedDistance += exitDistance;
+    }
+    
+    return STOP_RECURSION;
+}
+
+bool MetavoxelClientManager::findFirstRayHeightfieldIntersection(const glm::vec3& origin,
+        const glm::vec3& direction, float& distance) {
+    RayHeightfieldIntersectionVisitor visitor(origin, direction, getLOD());
+    guide(visitor);
+    if (visitor.intersectionDistance == FLT_MAX) {
+        return false;
+    }
+    distance = visitor.intersectionDistance;
+    return true;
+}
+
 void MetavoxelClientManager::setSphere(const glm::vec3& center, float radius, const QColor& color) {
     Sphere* sphere = new Sphere();
     sphere->setTranslation(center);
@@ -78,6 +252,84 @@ void MetavoxelClientManager::applyEdit(const MetavoxelEditMessage& edit, bool re
     QMetaObject::invokeMethod(_updater, "applyEdit", Q_ARG(const MetavoxelEditMessage&, edit), Q_ARG(bool, reliable));
 }
 
+class HeightfieldHeightVisitor : public MetavoxelVisitor {
+public:
+    
+    float height;
+    
+    HeightfieldHeightVisitor(const MetavoxelLOD& lod, const glm::vec3& location);
+    
+    virtual int visit(MetavoxelInfo& info);
+
+private:
+    
+    glm::vec3 _location;
+};
+
+HeightfieldHeightVisitor::HeightfieldHeightVisitor(const MetavoxelLOD& lod, const glm::vec3& location) :
+    MetavoxelVisitor(QVector<AttributePointer>() << AttributeRegistry::getInstance()->getHeightfieldAttribute(),
+        QVector<AttributePointer>(), lod),
+    height(-FLT_MAX),
+    _location(location) {
+}
+
+static const int REVERSE_ORDER = MetavoxelVisitor::encodeOrder(7, 6, 5, 4, 3, 2, 1, 0);
+
+int HeightfieldHeightVisitor::visit(MetavoxelInfo& info) {
+    glm::vec3 relative = _location - info.minimum;
+    if (relative.x < 0.0f || relative.z < 0.0f || relative.x > info.size || relative.z > info.size ||
+            height >= info.minimum.y + info.size) {
+        return STOP_RECURSION;
+    }
+    if (!info.isLeaf) {
+        return REVERSE_ORDER;
+    }
+    HeightfieldDataPointer pointer = info.inputValues.at(0).getInlineValue<HeightfieldDataPointer>();
+    if (!pointer) {
+        return STOP_RECURSION;
+    }
+    const QByteArray& contents = pointer->getContents();
+    const uchar* src = (const uchar*)contents.constData();
+    int size = glm::sqrt((float)contents.size());
+    int highest = size - 1;
+    relative *= highest / info.size;
+    
+    // find the bounds of the cell containing the point and the shared vertex heights
+    glm::vec3 floors = glm::floor(relative);
+    glm::vec3 ceils = glm::ceil(relative);
+    glm::vec3 fracts = glm::fract(relative);
+    int floorX = qMin(qMax((int)floors.x, 0), highest);
+    int floorZ = qMin(qMax((int)floors.z, 0), highest);
+    int ceilX = qMin(qMax((int)ceils.x, 0), highest);
+    int ceilZ = qMin(qMax((int)ceils.z, 0), highest);
+    float upperLeft = src[floorZ * size + floorX];
+    float lowerRight = src[ceilZ * size + ceilX];
+    float interpolatedHeight;
+    
+    // the final vertex (and thus which triangle we check) depends on which half we're on
+    if (fracts.x > fracts.z) {
+        float upperRight = src[floorZ * size + ceilX];
+        interpolatedHeight = glm::mix(glm::mix(upperLeft, upperRight, fracts.x), lowerRight, fracts.z);
+        
+    } else {
+        float lowerLeft = src[ceilZ * size + floorX];
+        interpolatedHeight = glm::mix(upperLeft, glm::mix(lowerLeft, lowerRight, fracts.x), fracts.z);
+    }
+    if (interpolatedHeight == 0.0f) {
+        return STOP_RECURSION; // ignore zero values
+    }
+    
+    // convert the interpolated height into world space
+    height = qMax(height, info.minimum.y + interpolatedHeight * info.size * EIGHT_BIT_MAXIMUM_RECIPROCAL);
+    return SHORT_CIRCUIT;
+}
+
+float MetavoxelClientManager::getHeightfieldHeight(const glm::vec3& location) {
+    HeightfieldHeightVisitor visitor(getLOD(), location);
+    guide(visitor);
+    return visitor.height;
+}
+
 MetavoxelLOD MetavoxelClientManager::getLOD() {
     return MetavoxelLOD();
 }

libraries/metavoxels/src/MetavoxelClientManager.h

@@ -37,12 +37,16 @@ public:
     SharedObjectPointer findFirstRaySpannerIntersection(const glm::vec3& origin, const glm::vec3& direction,
         const AttributePointer& attribute, float& distance);
 
+    bool findFirstRayHeightfieldIntersection(const glm::vec3& origin, const glm::vec3& direction, float& distance);
+
     Q_INVOKABLE void setSphere(const glm::vec3& center, float radius, const QColor& color = QColor(Qt::gray));
 
     Q_INVOKABLE void setSpanner(const SharedObjectPointer& object, bool reliable = false);
         
     Q_INVOKABLE void applyEdit(const MetavoxelEditMessage& edit, bool reliable = false);
 
+    Q_INVOKABLE float getHeightfieldHeight(const glm::vec3& location);
+
     /// Returns the current LOD.  This must be thread-safe, as it will be called from the updater thread.
     virtual MetavoxelLOD getLOD();
     

libraries/metavoxels/src/MetavoxelMessages.cpp

@@ -318,3 +318,169 @@ SetDataEdit::SetDataEdit(const glm::vec3& minimum, const MetavoxelData& data, bo
 void SetDataEdit::apply(MetavoxelData& data, const WeakSharedObjectHash& objects) const {
     data.set(minimum, this->data, blend);
 }
+
+PaintHeightfieldHeightEdit::PaintHeightfieldHeightEdit(const glm::vec3& position, float radius, float height) :
+    position(position),
+    radius(radius),
+    height(height) {
+}
+
+class PaintHeightfieldHeightEditVisitor : public MetavoxelVisitor {
+public:
+    
+    PaintHeightfieldHeightEditVisitor(const PaintHeightfieldHeightEdit& edit);
+    
+    virtual int visit(MetavoxelInfo& info);
+
+private:
+    
+    PaintHeightfieldHeightEdit _edit;
+    Box _bounds;
+};
+
+PaintHeightfieldHeightEditVisitor::PaintHeightfieldHeightEditVisitor(const PaintHeightfieldHeightEdit& edit) :
+    MetavoxelVisitor(QVector<AttributePointer>() << AttributeRegistry::getInstance()->getHeightfieldAttribute(),
+        QVector<AttributePointer>() << AttributeRegistry::getInstance()->getHeightfieldAttribute()),
+    _edit(edit) {
+    
+    glm::vec3 extents(_edit.radius, _edit.radius, _edit.radius);
+    _bounds = Box(_edit.position - extents, _edit.position + extents);
+}
+
+int PaintHeightfieldHeightEditVisitor::visit(MetavoxelInfo& info) {
+    if (!info.getBounds().intersects(_bounds)) {
+        return STOP_RECURSION;
+    }
+    if (!info.isLeaf) {
+        return DEFAULT_ORDER;
+    }
+    HeightfieldDataPointer pointer = info.inputValues.at(0).getInlineValue<HeightfieldDataPointer>();
+    if (!pointer) {
+        return STOP_RECURSION;
+    }
+    QByteArray contents(pointer->getContents());
+    int size = glm::sqrt((float)contents.size());
+    int highest = size - 1;
+    float heightScale = highest / info.size;
+    
+    glm::vec3 center = (_edit.position - info.minimum) * heightScale;
+    float scaledRadius = _edit.radius * heightScale;
+    glm::vec3 extents(scaledRadius, scaledRadius, scaledRadius);
+    
+    glm::vec3 start = glm::floor(center - extents);
+    glm::vec3 end = glm::ceil(center + extents);
+    
+    // raise/lower all points within the radius
+    float z = qMax(start.z, 0.0f);
+    float startX = qMax(start.x, 0.0f), endX = qMin(end.x, (float)highest);
+    uchar* lineDest = (uchar*)contents.data() + (int)z * size + (int)startX;
+    float squaredRadius = scaledRadius * scaledRadius;
+    float squaredRadiusReciprocal = 1.0f / squaredRadius;
+    const int EIGHT_BIT_MAXIMUM = 255; 
+    float scaledHeight = _edit.height * EIGHT_BIT_MAXIMUM / info.size;
+    for (float endZ = qMin(end.z, (float)highest); z <= endZ; z += 1.0f) {
+        uchar* dest = lineDest;
+        for (float x = startX; x <= endX; x += 1.0f, dest++) {
+            float dx = x - center.x, dz = z - center.z;
+            float distanceSquared = dx * dx + dz * dz;
+            if (distanceSquared <= squaredRadius) {
+                // height falls off towards edges
+                int value = *dest + scaledHeight * (squaredRadius - distanceSquared) * squaredRadiusReciprocal;
+                *dest = qMin(qMax(value, 0), EIGHT_BIT_MAXIMUM);
+            }
+        }
+        lineDest += size;
+    }
+    
+    HeightfieldDataPointer newPointer(new HeightfieldData(contents));
+    info.outputValues[0] = AttributeValue(_outputs.at(0), encodeInline<HeightfieldDataPointer>(newPointer));
+    return STOP_RECURSION;
+}
+
+void PaintHeightfieldHeightEdit::apply(MetavoxelData& data, const WeakSharedObjectHash& objects) const {
+    PaintHeightfieldHeightEditVisitor visitor(*this);
+    data.guide(visitor);
+}
+
+PaintHeightfieldColorEdit::PaintHeightfieldColorEdit(const glm::vec3& position, float radius, const QColor& color) :
+    position(position),
+    radius(radius),
+    color(color) {
+}
+
+class PaintHeightfieldColorEditVisitor : public MetavoxelVisitor {
+public:
+    
+    PaintHeightfieldColorEditVisitor(const PaintHeightfieldColorEdit& edit);
+    
+    virtual int visit(MetavoxelInfo& info);
+
+private:
+    
+    PaintHeightfieldColorEdit _edit;
+    Box _bounds;
+};
+
+PaintHeightfieldColorEditVisitor::PaintHeightfieldColorEditVisitor(const PaintHeightfieldColorEdit& edit) :
+    MetavoxelVisitor(QVector<AttributePointer>() << AttributeRegistry::getInstance()->getHeightfieldColorAttribute(),
+        QVector<AttributePointer>() << AttributeRegistry::getInstance()->getHeightfieldColorAttribute()),
+    _edit(edit) {
+    
+    glm::vec3 extents(_edit.radius, _edit.radius, _edit.radius);
+    _bounds = Box(_edit.position - extents, _edit.position + extents);
+}
+
+int PaintHeightfieldColorEditVisitor::visit(MetavoxelInfo& info) {
+    if (!info.getBounds().intersects(_bounds)) {
+        return STOP_RECURSION;
+    }
+    if (!info.isLeaf) {
+        return DEFAULT_ORDER;
+    }
+    HeightfieldDataPointer pointer = info.inputValues.at(0).getInlineValue<HeightfieldDataPointer>();
+    if (!pointer) {
+        return STOP_RECURSION;
+    }
+    QByteArray contents(pointer->getContents());
+    const int BYTES_PER_PIXEL = 3;
+    int size = glm::sqrt((float)contents.size() / BYTES_PER_PIXEL);
+    int highest = size - 1;
+    float heightScale = highest / info.size;
+    
+    glm::vec3 center = (_edit.position - info.minimum) * heightScale;
+    float scaledRadius = _edit.radius * heightScale;
+    glm::vec3 extents(scaledRadius, scaledRadius, scaledRadius);
+    
+    glm::vec3 start = glm::floor(center - extents);
+    glm::vec3 end = glm::ceil(center + extents);
+    
+    // paint all points within the radius
+    float z = qMax(start.z, 0.0f);
+    float startX = qMax(start.x, 0.0f), endX = qMin(end.x, (float)highest);
+    int stride = size * BYTES_PER_PIXEL;
+    char* lineDest = contents.data() + (int)z * stride + (int)startX * BYTES_PER_PIXEL;
+    float squaredRadius = scaledRadius * scaledRadius; 
+    char red = _edit.color.red(), green = _edit.color.green(), blue = _edit.color.blue();
+    for (float endZ = qMin(end.z, (float)highest); z <= endZ; z += 1.0f) {
+        char* dest = lineDest;
+        for (float x = startX; x <= endX; x += 1.0f, dest += BYTES_PER_PIXEL) {
+            float dx = x - center.x, dz = z - center.z;
+            if (dx * dx + dz * dz <= squaredRadius) {
+                dest[0] = red;
+                dest[1] = green;
+                dest[2] = blue;
+            }
+        }
+        lineDest += stride;
+    }
+    
+    HeightfieldDataPointer newPointer(new HeightfieldData(contents));
+    info.outputValues[0] = AttributeValue(_outputs.at(0), encodeInline<HeightfieldDataPointer>(newPointer));
+    return STOP_RECURSION;
+}
+
+void PaintHeightfieldColorEdit::apply(MetavoxelData& data, const WeakSharedObjectHash& objects) const {
+    PaintHeightfieldColorEditVisitor visitor(*this);
+    data.guide(visitor);
+}
+

libraries/metavoxels/src/MetavoxelMessages.h

@@ -207,4 +207,38 @@ public:
 
 DECLARE_STREAMABLE_METATYPE(SetDataEdit)
 
+/// An edit that sets a region of a heightfield height.
+class PaintHeightfieldHeightEdit : public MetavoxelEdit {
+    STREAMABLE
+
+public:
+    
+    STREAM glm::vec3 position;
+    STREAM float radius;
+    STREAM float height;
+    
+    PaintHeightfieldHeightEdit(const glm::vec3& position = glm::vec3(), float radius = 0.0f, float height = 0.0f);
+    
+    virtual void apply(MetavoxelData& data, const WeakSharedObjectHash& objects) const;
+};
+
+DECLARE_STREAMABLE_METATYPE(PaintHeightfieldHeightEdit)
+
+/// An edit that sets a region of a heightfield color.
+class PaintHeightfieldColorEdit : public MetavoxelEdit {
+    STREAMABLE
+
+public:
+    
+    STREAM glm::vec3 position;
+    STREAM float radius;
+    STREAM QColor color;
+    
+    PaintHeightfieldColorEdit(const glm::vec3& position = glm::vec3(), float radius = 0.0f, const QColor& color = QColor());
+    
+    virtual void apply(MetavoxelData& data, const WeakSharedObjectHash& objects) const;
+};
+
+DECLARE_STREAMABLE_METATYPE(PaintHeightfieldColorEdit)
+
 #endif // hifi_MetavoxelMessages_h

libraries/metavoxels/src/MetavoxelUtil.h

@@ -138,6 +138,8 @@ public:
     
     QColorEditor(QWidget* parent);
 
+    const QColor& getColor() const { return _color; }
+
 signals:
 
     void colorChanged(const QColor& color);

libraries/networking/src/PacketHeaders.cpp

@@ -80,6 +80,8 @@ PacketVersion versionForPacketType(PacketType type) {
             return 1;
         case PacketTypeAudioStreamStats:
             return 1;
+        case PacketTypeMetavoxelData:
+            return 1;
         default:
             return 0;
     }