TRIANGULAR TESSELLATION SERIAL
TRIANGULAR TESSELLATION PATCH

Much like a VS program, each TC program transforms only one vertex, and the number of execution instances is the same as the number of verts in your OpenGL draw call. The Tessellation Control (TC) shader is kinda like a Vertex Shader (VS) with super-vision. GlDrawArrays(GL_PATCHES, firstVert, vertCount) // draw a bunch of patches

TRIANGULAR TESSELLATION PATCH

GlPatchParameteri(GL_PATCH_VERTICES, 16) // tell OpenGL that every patch has 16 verts Unlike GL_TRIANGLES (where every 3 verts spawns a triangle) or GL_TRIANGLE_STRIP (where every 1 vert spawns a new triangle), the number of verts in a patch is configurable:

To work with tessellation shaders, OpenGL now has a new primitive type: GL_PATCHES. However, much like geometry shaders, they can “see” all the verts in a single primitive.

TRIANGULAR TESSELLATION SERIAL

They both execute on a per-vertex basis, so their programs typically don’t have serial loops like the old-fashioned geometry programs did. So, we now have two additional programmable stages at our disposal: Tessellation Control and Tessellation Evaluation. Now is the time for the obligatory diagram: (I used a red pen for the stages that are new to OpenGL 4.0) The New OpenGL 4.0+ PipelineĪlthough adding multiple GS invocations was helpful, performing highly-efficient subdivision demanded brand new stages in the pipeline. You can figure out which vert you’re on by looking at the built-in gl_InvocationID variable. This tells the GPU that your GS should run three times on a single primitive. Nowadays you can do a bit better by specifying an invocations count at the top of your GS, like so: They didn’t do a great job of leveraging the massive parallelism in GPUs. Most GS programs had a serial loop that simply pushed out the verts of the new primitive(s), one vertex after another. The GS processing for a single primitive was initially limited to a single processing unit.

It was not designed for large-scale amplification of vertex data. The GS unit turned out to be convenient for certain effects, but overall it was somewhat disappointing. And finally, the GPU could produce more primitives than it consumed. When Geometry Shaders (GS) first came out, we were all excited because we could finally write a shader that could “see” all the verts in a triangle at once. This entry gives an overview of tessellation and walks through an example of simple triangle subdivision in the next entry, we’ll focus on quad subdivision.

+ radical cations and one neutral TTF molecule.This is the first of a two-part article on tessellation shaders with OpenGL 4.0+.

Solid-state spectroscopic investigations on CT-C revealed the existence of an absorption band at 2500 nm, which on the basis of TDDFT calculations, was attributed to the mixed-valence character between two TTF In the CT-C superstructure, three TTF molecules self-assemble, forming a supramolecular isosceles triangle TTF-Δ, which tiles in a plane alongside the NDI-Δ, producing a 3 + 3 honeycomb tiling pattern of the two different polygons. In the CT-B superstructure, the CHCl 3 lattice molecules establish a set of and intermolecular interactions, leading to the formation of a hexagonal grid of solvent in which NDI-Δ forms a triangular grid. Confinement of TTF inside the NDI-Δ cavities in the CT-A superstructure enhances the CT character with the observation of a broad absorption band in the NIR region. Solvent modulation plays a critical role in controlling not only the NDI-Δ: TTF stoichiometric ratios and the molecular arrangements in the crystal superstructures, but also prevents the inclusion of TTF guests inside the cavities of NDI-Δ. Using MeCN, CHCl 3, and CH 2Cl 2, we identified three sets of cocrystals, namely CT-A, CT-B, and CT-C, respectively. Different solvents lead to different packing arrangements. Cocrystallization of NDI-Δ with tetrathiafulvalene ( TTF) leads systematically to the formation of 2D tessellations as a result of superstructure-directing CT interactions. Utilization of nonhalogenated solvents, combined with careful tailoring of the concentrations, results in NDI-Δ self-assembling though interactions into 2D honeycomb triangular and hexagonal tiling patterns. Our approach to exploring the 3D topology of 2D tessellations of a naphthalene diimide-based molecular triangle ( NDI-Δ) reveals that the 2D molecular arrangement is sensitive to the identity of the solvent and solute concentrations. Tessellation of organic polygons though and charge-transfer (CT) interactions offers a unique opportunity to construct supramolecular organic electronic materials with 2D topologies.

Triangular tessellation