Tweak volume shaders.

Also fix custom object default texture.

Change-Id: Iba9ff6afb807d9f7a4e1f58b0e5fb4bca4c9c431
Reviewed-by: Mika Salmela <mika.salmela@digia.com>

4 files changed, 102 insertions, 81 deletions

diff --git a/src/datavisualization/data/customrenderitem.cpp b/src/datavisualization/data/customrenderitem.cpp
index b96a4957..3eb68845 100644
--- a/src/datavisualization/data/customrenderitem.cpp
+++ b/src/datavisualization/data/customrenderitem.cpp
@@ -52,13 +52,17 @@ void CustomRenderItem::setMesh(const QString &meshFile)
 
 void CustomRenderItem::setColorTable(const QVector<QRgb> &colors)
 {
-    m_colorTable.resize(colors.size());
-    for (int i = 0; i < m_colorTable.size(); i++) {
-        const QRgb &rgb = colors.at(i);
-        m_colorTable[i] = QVector4D(float(qRed(rgb)) / 255.0f,
-                                    float(qGreen(rgb)) / 255.0f,
-                                    float(qBlue(rgb)) / 255.0f,
-                                    float(qAlpha(rgb)) / 255.0f);
+    m_colorTable.resize(256);
+    for (int i = 0; i < 256; i++) {
+        if (i < colors.size()) {
+            const QRgb &rgb = colors.at(i);
+            m_colorTable[i] = QVector4D(float(qRed(rgb)) / 255.0f,
+                                        float(qGreen(rgb)) / 255.0f,
+                                        float(qBlue(rgb)) / 255.0f,
+                                        float(qAlpha(rgb)) / 255.0f);
+        } else {
+            m_colorTable[i] = QVector4D(0.0f, 0.0f, 0.0f, 0.0f);
+        }
     }
 }
 
diff --git a/src/datavisualization/data/qcustom3ditem.cpp b/src/datavisualization/data/qcustom3ditem.cpp
index 1d419cee..cb843b62 100644
--- a/src/datavisualization/data/qcustom3ditem.cpp
+++ b/src/datavisualization/data/qcustom3ditem.cpp
@@ -367,6 +367,7 @@ QString QCustom3DItem::textureFile() const
 
 QCustom3DItemPrivate::QCustom3DItemPrivate(QCustom3DItem *q) :
     q_ptr(q),
+    m_textureImage(QImage(1, 1, QImage::Format_ARGB32)),
     m_position(QVector3D(0.0f, 0.0f, 0.0f)),
     m_positionAbsolute(false),
     m_scaling(QVector3D(0.1f, 0.1f, 0.1f)),
@@ -382,6 +383,7 @@ QCustom3DItemPrivate::QCustom3DItemPrivate(QCustom3DItem *q, const QString &mesh
                                            const QVector3D &position, const QVector3D &scaling,
                                            const QQuaternion &rotation) :
     q_ptr(q),
+    m_textureImage(QImage(1, 1, QImage::Format_ARGB32)),
     m_meshFile(meshFile),
     m_position(position),
     m_positionAbsolute(false),
diff --git a/src/datavisualization/engine/shaders/texture3d.frag b/src/datavisualization/engine/shaders/texture3d.frag
index e56506ff..90876596 100644
--- a/src/datavisualization/engine/shaders/texture3d.frag
+++ b/src/datavisualization/engine/shaders/texture3d.frag
@@ -12,78 +12,90 @@ uniform highp int sampleCount; // This is the maximum sample count
 const highp float alphaThreshold = 0.0001;
 
 void main() {
-    // Raytrace into volume, need to sample pixels along the eye ray until we hit opacity 1
-
-    // Find out where ray intersects the object
     highp vec3 rayDir = -(cameraPositionRelativeToModel - pos);
-    highp vec3 invRayDir = 1.0 / rayDir;
-    highp vec3 minCorner = vec3(-1.0);
-    highp vec3 maxCorner = vec3(1.0);
-    highp vec3 t1 = invRayDir * (minCorner - pos);
-    highp vec3 t2 = invRayDir * (maxCorner - pos);
-    highp vec3 tmin = min(t1, t2);
-    highp vec3 tmax = max(t1, t2);
-    highp vec2 t = max(tmin.xx, tmin.yz);
-    t = min(tmax.xx, tmax.yz);
-    float tFar = min(t.x, t.y);
-    highp vec3 rayStart = pos;
+    vec3 rayStart = pos;
     // Flip Y and Z so QImage bits work directly for texture and first image is in the front
+    rayDir.yz = -rayDir.yz;
     rayStart.yz = -rayStart.yz;
-    highp vec3 rayStop = pos + rayDir * tFar;
-    rayStop.yz = -rayStop.yz;
-
-    // Convert intersections to texture coords
-    rayStart = 0.5 * (rayStart + 1.0);
-    rayStop = 0.5 * (rayStop + 1.0);
-
-    highp vec3 ray = rayStop - rayStart;
-    highp float fullDist = length(ray);
-    highp float rayX = abs(ray.x) * textureDimensions.x;
-    highp float rayY = abs(ray.y) * textureDimensions.y;
-    highp float rayZ = abs(ray.z) * textureDimensions.z;
-
-    highp float maxRayDim = max(rayX, rayY);
-    maxRayDim = max(maxRayDim, rayZ);
-
-    highp vec3 step = ray / maxRayDim;
-    highp float stepSize = abs(fullDist / maxRayDim);
-
-    // Offset a fraction of a step so we are not exactly on a texel boundary.
-    highp vec3 curPos = rayStart - (0.5 * step);
 
-    // Adjust alpha multiplier according to the step size to get uniform alpha effect
-    // regardless of the ray angle.
-    highp float alphaMultiplier = stepSize / (1.0 / sampleCount);
+    // Calculate ray intersection endpoint
+    vec3 rayStop;
+    if (rayDir.x == 0.0) {
+        rayStop.yz = rayStart.yz;
+        rayStop.x = -rayStart.x;
+    } else if (rayDir.y == 0.0) {
+        rayStop.xz = rayStart.xz;
+        rayStop.y = -rayStart.y;
+    } else if (rayDir.z == 0.0) {
+        rayStop.xy = rayStart.xy;
+        rayStop.z = -rayStart.z;
+    } else {
+        highp vec3 boxBounds = vec3(1.0, 1.0, 1.0);
+        highp vec3 invRayDir = 1.0 / rayDir;
+        if (rayDir.x < 0)
+            boxBounds.x = -1.0;
+        if (rayDir.y < 0)
+            boxBounds.y = -1.0;
+        if (rayDir.z < 0)
+            boxBounds.z = -1.0;
+        highp vec3 t = (boxBounds - rayStart) * invRayDir;
+        highp float minT = min(t.x, t.y);
+        minT = min(minT, t.z);
+        rayStop = rayStart + minT * rayDir;
+    }
 
-    highp float totalDist = 0.0;
-    highp float totalAlpha = 0.0;
     highp vec4 destColor = vec4(0, 0, 0, 0);
-    highp vec4 curColor = vec4(0, 0, 0, 0);
-    highp vec3 curRgb = vec3(0, 0, 0);
-    highp float curAlpha = 0.0;
-
-    for (int i = 0; i < sampleCount; i++) {
-        curColor = texture3D(textureSampler, curPos);
-        if (color8Bit != 0)
-            curColor = colorIndex[int(curColor.r * 255.0)];
+    highp float totalAlpha = 0.0;
 
-        if (curColor.a == 1.0)
-            curAlpha = 1.0;
-        else
-            curAlpha = clamp(curColor.a * alphaMultiplier, 0.0, 1.0);
-        if (curAlpha > alphaThreshold) {
-            curRgb = curColor.rgb * curAlpha * (1.0 - totalAlpha);
-            destColor.rgb += curRgb;
-            totalAlpha += curAlpha;
-        }
-        curPos += step;
-        totalDist += stepSize;
-        if (totalDist > fullDist || totalAlpha >= 1.0) {
-            break;
+    if (rayStart != rayStop) {
+        // Convert intersections to texture coords
+        rayStart = 0.5 * (rayStart + 1.0);
+        rayStop = 0.5 * (rayStop + 1.0);
+
+        highp vec3 ray = rayStop - rayStart;
+        highp float fullDist = abs(length(ray));
+        highp float rayX = abs(ray.x) * textureDimensions.x;
+        highp float rayY = abs(ray.y) * textureDimensions.y;
+        highp float rayZ = abs(ray.z) * textureDimensions.z;
+        highp float maxRayDim = max(rayX, rayY);
+        maxRayDim = max(maxRayDim, rayZ);
+        int maxCount = int(floor(maxRayDim));
+
+        highp vec3 step = ray / maxRayDim;
+        highp float stepSize = fullDist / maxRayDim;
+
+        rayStart += (step * 0.001);
+        highp vec3 curPos = rayStart;
+
+        // Adjust alpha multiplier according to the step size to get uniform alpha effect
+        // regardless of the ray angle.
+        highp float alphaMultiplier = stepSize / (1.0 / sampleCount);
+
+        highp vec4 curColor = vec4(0, 0, 0, 0);
+        highp vec3 curRgb = vec3(0, 0, 0);
+        highp float curAlpha = 0.0;
+
+        // Raytrace into volume, need to sample pixels along the eye ray until we hit opacity 1
+        for (int i = 0; i < sampleCount; i++) {
+            curColor = texture3D(textureSampler, curPos);
+            if (color8Bit != 0)
+                curColor = colorIndex[int(curColor.r * 255.0)];
+
+            if (curColor.a == 1.0)
+                curAlpha = 1.0;
+            else
+                curAlpha = clamp(curColor.a * alphaMultiplier, 0.0, 1.0);
+            if (curAlpha > alphaThreshold) {
+                curRgb = curColor.rgb * curAlpha * (1.0 - totalAlpha);
+                destColor.rgb += curRgb;
+                totalAlpha += curAlpha;
+            }
+            if (i == maxCount || totalAlpha >= 1.0)
+                break;
+            curPos += step;
         }
     }
 
     destColor.a = totalAlpha;
     gl_FragColor = clamp(destColor, 0.0, 1.0);
 }
-
diff --git a/src/datavisualization/engine/shaders/texture3dslice.frag b/src/datavisualization/engine/shaders/texture3dslice.frag
index e095bc5f..409ab41d 100644
--- a/src/datavisualization/engine/shaders/texture3dslice.frag
+++ b/src/datavisualization/engine/shaders/texture3dslice.frag
@@ -15,24 +15,27 @@ const highp vec3 zPlaneNormal = vec3(0, 0, 1.0);
 const highp float alphaThreshold = 0.0001;
 
 void main() {
-    // Raytrace into volume, need to sample pixels along the eye ray until we hit opacity 1
-
     // Find out where ray intersects the slice planes
     highp vec3 rayDir = -(cameraPositionRelativeToModel - pos);
+    rayDir = normalize(rayDir);
     highp vec3 rayStart = pos;
     // Flip Y and Z so QImage bits work directly for texture and first image is in the front
     rayStart.yz = -rayStart.yz;
     rayDir.yz = -rayDir.yz;
-    highp vec3 invRayDir = 1.0 / rayDir;
-    highp vec3 minCorner = vec3(-1.0);
-    highp vec3 maxCorner = vec3(1.0);
-    highp vec3 t1 = invRayDir * (minCorner - rayStart);
-    highp vec3 t2 = invRayDir * (maxCorner - rayStart);
-    highp vec3 tmin = min(t1, t2);
-    highp vec3 tmax = max(t1, t2);
-    highp vec2 t = max(tmin.xx, tmin.yz);
-    t = min(tmax.xx, tmax.yz);
-    float tFar = min(t.x, t.y);
+    highp float tFar = 2.0f;
+    if (rayDir.x != 0.0 && rayDir.y != 0.0 && rayDir.z != 0.0) {
+        highp vec3 boxBounds = vec3(1.0, 1.0, 1.0);
+        highp vec3 invRayDir = 1.0 / rayDir;
+        if (rayDir.x < 0)
+            boxBounds.x = -1.0;
+        if (rayDir.y < 0)
+            boxBounds.y = -1.0;
+        if (rayDir.z < 0)
+            boxBounds.z = -1.0;
+        highp vec3 t = (boxBounds - rayStart) * invRayDir;
+        tFar = max(t.x, t.y);
+        tFar = max(tFar, t.z);
+    }
 
     highp vec3 xPoint = vec3(volumeSliceIndices.x, 0, 0);
     highp vec3 yPoint = vec3(0, volumeSliceIndices.y, 0);