Shaders: improve MeshVisualizer docs.

doc/snippets/MagnumShaders.cpp

@@ -274,7 +274,7 @@ shader.setColor(0x2f83cc_rgbf)
 mesh.draw(shader);
 /* [MeshVisualizer-usage-geom2] */
 
-/* [MeshVisualizer-usage-no-geom-old1] */
+/* [MeshVisualizer-usage-no-geom-old] */
 Containers::Array<Float> vertexIndex{Containers::arraySize(data)};
 std::iota(vertexIndex.begin(), vertexIndex.end(), 0.0f);
 
@@ -282,27 +282,12 @@ GL::Buffer vertexIndices;
 vertexIndices.setData(vertexIndex, GL::BufferUsage::StaticDraw);
 
 mesh.addVertexBuffer(vertexIndices, 0, Shaders::MeshVisualizer::VertexIndex{});
-/* [MeshVisualizer-usage-no-geom-old1] */
+/* [MeshVisualizer-usage-no-geom-old] */
 }
 #endif
 
 {
-GL::Mesh mesh;
-/* [MeshVisualizer-usage-no-geom-old2] */
-Matrix4 transformationMatrix, projectionMatrix;
-
-Shaders::MeshVisualizer shader{Shaders::MeshVisualizer::Flag::Wireframe|
-                               Shaders::MeshVisualizer::Flag::NoGeometryShader};
-shader.setColor(0x2f83cc_rgbf)
-    .setWireframeColor(0xdcdcdc_rgbf)
-    .setTransformationProjectionMatrix(projectionMatrix*transformationMatrix);
-
-mesh.draw(shader);
-/* [MeshVisualizer-usage-no-geom-old2] */
-}
-
-{
-/* [MeshVisualizer-usage-no-geom] */
+/* [MeshVisualizer-usage-no-geom1] */
 std::vector<UnsignedInt> indices{
     // ...
 };
@@ -317,9 +302,23 @@ vertices.setData(MeshTools::duplicate(indices, indexedPositions),
 
 GL::Mesh mesh;
 mesh.addVertexBuffer(vertices, 0, Shaders::MeshVisualizer::Position{});
-/* [MeshVisualizer-usage-no-geom] */
+/* [MeshVisualizer-usage-no-geom1] */
 }
 
+{
+GL::Mesh mesh;
+/* [MeshVisualizer-usage-no-geom2] */
+Matrix4 transformationMatrix, projectionMatrix;
+
+Shaders::MeshVisualizer shader{Shaders::MeshVisualizer::Flag::Wireframe|
+                               Shaders::MeshVisualizer::Flag::NoGeometryShader};
+shader.setColor(0x2f83cc_rgbf)
+    .setWireframeColor(0xdcdcdc_rgbf)
+    .setTransformationProjectionMatrix(projectionMatrix*transformationMatrix);
+
+mesh.draw(shader);
+/* [MeshVisualizer-usage-no-geom2] */
+}
 #if !defined(__GNUC__) || defined(__clang__) || __GNUC__*100 + __GNUC_MINOR__ >= 500
 {
 /* [Phong-usage-colored1] */

src/Magnum/Shaders/MeshVisualizer.h

@@ -74,7 +74,7 @@ is optionally used for improving line appearance.
 
 @section Shaders-MeshVisualizer-usage Example usage
 
-@subsection Shaders-MeshVisualizer-usage-wireframe-geom Wireframe visualization with geometry shader (desktop GL)
+@subsection Shaders-MeshVisualizer-usage-wireframe-geom Wireframe visualization with a geometry shader (desktop GL, OpenGL ES 3.2)
 
 Common mesh setup:
 
@@ -84,22 +84,22 @@ Common rendering setup:
 
 @snippet MagnumShaders.cpp MeshVisualizer-usage-geom2
 
-@subsection Shaders-MeshVisualizer-usage-wireframe-no-geom-old Wireframe visualization without geometry shader on older hardware
+@subsection Shaders-MeshVisualizer-usage-wireframe-no-geom Wireframe visualization of indexed meshes without a geometry shader
 
-You need to provide also the @ref VertexIndex attribute. Mesh setup *in
-addition to the above*:
+The vertices have to be be converted to a non-indexed array. Mesh setup:
 
-@snippet MagnumShaders.cpp MeshVisualizer-usage-no-geom-old1
+@snippet MagnumShaders.cpp MeshVisualizer-usage-no-geom1
 
 Rendering setup:
 
-@snippet MagnumShaders.cpp MeshVisualizer-usage-no-geom-old2
+@snippet MagnumShaders.cpp MeshVisualizer-usage-no-geom2
 
-@subsection Shaders-MeshVisualizer-usage-wireframe-no-geom Wireframe visualization of indexed meshes without geometry shader
+@subsection Shaders-MeshVisualizer-usage-wireframe-no-geom-old Wireframe visualization of non-indexed meshes without a geometry shader on older hardware
 
-The vertices must be converted to non-indexed array. Mesh setup:
+You need to provide also the @ref VertexIndex attribute. Mesh setup *in
+addition to the above*:
 
-@snippet MagnumShaders.cpp MeshVisualizer-usage-no-geom
+@snippet MagnumShaders.cpp MeshVisualizer-usage-no-geom-old
 
 Rendering setup the same as above.
 
@@ -123,8 +123,9 @@ class MAGNUM_SHADERS_EXPORT MeshVisualizer: public GL::AbstractShaderProgram {
          * 2.0 if @ref Flag::Wireframe is enabled. This attribute (modulo 3)
          * specifies index of given vertex in triangle, i.e. @cpp 0.0f @ce for
          * first, @cpp 1.0f @ce for second, @cpp 2.0f @ce for third. In OpenGL
-         * 3.1, OpenGL ES 3.0 and newer this value is provided by the shader
-         * itself, so the attribute is not needed.
+         * 3.1, OpenGL ES 3.0 and newer this value is provided via the
+         * @cb{.glsl} gl_VertexID @ce shader builtin, so the attribute is not
+         * needed.
          */
         typedef GL::Attribute<3, Float> VertexIndex;
 
@@ -156,7 +157,7 @@ class MAGNUM_SHADERS_EXPORT MeshVisualizer: public GL::AbstractShaderProgram {
             /**
              * Don't use geometry shader for wireframe visualization. If
              * enabled, you might need to provide also @ref VertexIndex
-             * attribute in the mesh. In OpenGL ES enabled alongside
+             * attribute in the mesh. In OpenGL ES 2.0 enabled alongside
              * @ref Flag::Wireframe.
              */
             NoGeometryShader = 1 << 1