Instantly draw vector graphics of photo-realistic quality using D-Type's revolutionary color shading rasterizer.

Overview

D-Type Shading Rasterizer is a portable and special-purpose rasterizer that allows you to render highly realistic scalable vector art, such as VIVO scalable photos, or complex SVG and gradient meshes sometimes found in other vector formats. In contrast with D-Type Direct Color Rasterizer, which can only process one color value per contour, D-Type Shading Rasterizer is designed to concurrently apply many RGBA color values to the same contour. More precisely, this rasterizer combines the energy of multiple spatially separated color sources to generate smooth color transitions, or color gradients, within each contour.

Typically one color source is located at each contour's vertex and a color interpolation algorithm is used to compute the final pixel color values inside the contour. D-Type Shading Rasterizer currently supports six such color interpolation algorithms:

• Mean Value Coordinates
• Distance Field - Method A
• Distance Field - Method B
• Inverse Distance Weighting
• Gouraud Shading With Anti-Aliased Edges
• Gouraud Shading Without Anti-Aliased Edges

The characteristics of these algorithms are illustrated further down. Despite their technical differences, they have one thing in common: all of them utilize multiple color sources to generate a smooth spectrum of colors or, alternatively, different shades of a single color, within the interior of individual contours. This smooth and gradual change of color — or color gradation — can be utilized to generate vector images that look highly realistic and yet are fully scalable and resolution independent.

This is best illustrated by the following example:

Notice that in the above images, no contour is painted using a single (flat) color value. Instead, the contours are painted using many different color shades which, as a result, produces a naturally looking texture. Also, note in the second magnified detail how the color outside the owl's outer edge changes gradually from white to light grey. Yet, the actual edge line is perfectly sharp and smooth.

The actual contours in a vector image can be triangles, polygons or other complex shapes consisting of straight and/or curved segments. D-Type Shading Rasterizer, unlike most traditional video cards, is not limited to rendering triangles only. With D-Type Shading Rasterizer end-user applications have a choice of creating much richer vector based geometries and taking advantage of how different color interpolation algorithms interact with such geometries. Also, D-Type Shading Rasterizer does not impose any restrictions on the complexity of the underlying geometry. In other words, applications can supply to the rasterizer just a few or, in highly realistic vector images, thousands of contours.

Much like D-Type Direct Color Rasterizer, D-Type Shading Rasterizer generates the entire vector image during the actual rasterization process, in a single pass. So it's super fast. In fact, the rendering machinery behind D-Type's VIVO Image Vectorizer relies on D-Type Shading Rasterizer to render extremely complex and detailed vector images designed to match or exceed the quality of high-resolution photographs.

Features

• Perfect stitching between adjacent fill areas
• A number of different color interpolation algorithms
  (Mean Value Coordinates, Distance Field, Inverse Distance Weighting, Gouraud Shading etc.)
• Smooth color/shading transition between adjacent fill areas (all algorithms except Inverse Distance Weighting)
• Ultra-fast rendering
• Absolutely amazing quality
• Extremely simple set of instructions
• Coordinates can be specified as whole pixel, float or fixed (fractional) values
• Renders extremely large multi-color RGBA scenes without difficulties
• Minimal hardware requirements
• Highly configurable

Specifications

Coordinates	Float, Integer, Fractional
Color Shading Algorithms	Mean Value Coordinates Distance Field - Method A Distance Field - Method B Inverse Distance Weighting Gouraud Shading With Anti-Aliased Edges Gouraud Shading Without Anti-Aliased Edges
Advanced Features	Amazing quality Perfect stitching between adjacent fill areas Smooth color/shading transition between adjacent fill areas (all algorithms except Inverse Distance Weighting) Not limited to rendering triangles only. Supports both convex and concave polygons and arbitrary shapes with straight and/or curved segments.
Availability	Windows Linux macOS iOS Android Windows Phone Windows RT XBox Raspberry Pi Zealz GK802 Mini PC Custom builds for virtually any other platform (32-bit and/or 64-bit)

Example 1

Disconnected Shapes

Each color shading algorithm has different characteristics with respect to how the color changes within the contour and/or along its edges. The following chart demonstrates these characteristics. On the left side of each illustration, the top shape (triangle) has yellow, green and red color sources at its corners; the one at the bottom (quadrilateral) has green, blue, blue and red. On the right side, the top shape (triangle) has blue, yellow and red color sources at its corners; the bottom one (triangle) has yellow, blue and red.

Conclusions

• All D-Type's color interpolation algorithms spread the energy of color sources from the vertices to the interior of the contour and along the edges.
• The distribution of color energy is smooth and gradual within the contour and along its edges.
• Additionally, all algorithms except Gouraud Shading Without Anti-Aliased Edges provide anti-aliasing at the edges of the contours.

Adjacent Shapes

This example is very similar to the first one, except that now the triangle and quadrilateral on the left have joined along their bottom and top edges, respectively. Similarly, the two triangles on the right have joined. This is to show the color transition between adjacent fill areas and the edge stitching behavior of each color interpolation algorithm.

Conclusions

• All color interpolation algorithms show perfect stitching between adjacent contours. This is true even for Gouraud Shading Without Anti-Aliased Edges which, as the name implies, does not support anti-aliasing at the edges.
• All color interpolation algorithms except Inverse Distance Weighting feature a smooth color/shading transition between adjacent fill areas, assuming the same color sources are placed at the vertices of the joined edges. The Mean Value Coordinates is best in this regard, followed by the two Gouraud Shading algorithms, and finally the Distance Field algorithms.
• The Inverse Distance Weighting algorithm is not designed (and should not be used) for creating smooth color/shading transitions outside of a single contour.

Example 2

Overlapping Shapes

Ideally, contours that are part of the vector based geometry (which D-Type Shading Rasterizer renders in a single rasterization pass) should not overlap. When they do overlap, end-user applications should be aware of the fact that different color interpolation algorithms will produce different results in the regions that overlap. This is illustrated in the following example:

Conclusions

• Different color interpolation algorithms provide different results in the overlapping regions. Only the Gouraud Shading Without Anti-Aliased Edges algorithm produces a result that is intuitively clear and useful. Due to this, it's best to avoid using overlapping shapes in the general case.

Example 3

Concave Shapes

As mentioned above, D-Type Shading Rasterizer is not limited to rendering triangles only. The contours in a vector image can be polygons or other complex shapes consisting of straight and/or curved segments. However, when rendering concave polygons and shapes, end-user applications should be aware of one limitation imposed by the Gouraud Shading algorithm, which does not exist in any other color interpolation algorithm. Let's have a look at the following example. Here we have a sample concave shape, with three color sources (red, yellow and blue) at its vertices:

Conclusions

• As the images above show, all color interpolation algorithms except Gouraud Shading feature a smooth and uniform color distribution across the entire interior of a concave shape.
• The Gouraud Shading algorithms show an abrupt color change in the regions inside the concave shape that are just below the shape's local y-value minima ("valleys") and just above the local y-value maxima ("hills"). This is caused by the very design of the Gouraud Shading algorithm, which always interpolates colors between two end points, in the horizontal direction. Thus, the Gouraud Shading algorithms should not be used when the vector geometry consists of concave polygons. Instead, all concave polygons should be broken down into two or more convex polygons, before they are processed using the Gouraud Shading interpolation algorithm. Note that this extra step is not necessary for any other color interpolation algorithm supported by D-Type Shading Rasterizer.