diff --git a/src/glutils.cpp b/src/glutils.cpp
index 1ee54bd..2dde313 100644
--- a/src/glutils.cpp
+++ b/src/glutils.cpp
@@ -102,3 +102,9 @@ GLuint fmri::compileShader(GLenum type, char const *source)
         abort();
     }
 }
+
+void ::fmri::setColorFromIntensity(float i)
+{
+    // TODO: something more expressive.
+    glColor3f(i, i, i);
+}
diff --git a/src/glutils.hpp b/src/glutils.hpp
index 2b947b1..3fedb87 100644
--- a/src/glutils.hpp
+++ b/src/glutils.hpp
@@ -33,4 +33,11 @@ namespace fmri {
      * @param h new Height.
      */
     void changeWindowSize(int w, int h);
+
+    /**
+     * Set the current drawing color based on some intensity value.
+     *
+     * @param i The intensity.
+     */
+    void setColorFromIntensity(float i);
 }
diff --git a/src/main.cpp b/src/main.cpp
index 954d44d..fa825b8 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -57,7 +57,9 @@ static void render()
 
     glPushMatrix();
     for (auto& layer : *rendererData.currentData) {
+        glPushMatrix();
         renderLayer(layer);
+        glPopMatrix();
         glTranslatef(-5, 0, 0);
     }
     glPopMatrix();
@@ -90,10 +92,10 @@ static void renderFlatLayer(const LayerData& data)
     // Color depends on current value.
     vector<float> intensities(data.data(), data.data() + data.numEntries());
     rescale(intensities.begin(), intensities.end(), 0, 1);
-    glColor3f(1, 1, 1);
 
     glPushMatrix();
     for (auto i : intensities) {
+        setColorFromIntensity(i);
         drawOneParticle();
         glTranslatef(0, 0, -2);
     }
@@ -118,6 +120,8 @@ static void renderLayer(const LayerData& data)
     // Draw the name of the layer for reference.
     glColor3f(0.5, 0.5, 0.5);
     renderText(data.name());
+
+    glTranslatef(0, 0, -2);
     switch (shape.size()) {
         case 4:
             // TODO: implement this.