The purpose of this thesis is to develop a texture-based painterly shader that would render computer generated objects or scenes with strokes that are visually similar to paint media like watercolor, oil paint or dry media such as crayons, chalk, et cetera. This method would need an input scene in the form of three dimensional polygonal or NURBS meshes. While the structure of the meshes and the lighting in the scene would both play a crucial role in the final appearance of the scene, the painterly look will be imparted through a shader. This method, therefore, is essentially a rendering technique. Several modifiable parameters in the shader gives the user artistic freedom while overall introducing some amount of automation in the painterly rendering process.

In order to increase the data-path utilization of the programmable graphics processor units (GPU) which often stall by waiting for the execution results of those long-latency instructions, multi-thread technique is very often used in the design of GPU. This thesis proposes a multi-thread single unified core GPU design which owns several key features. First, its processor core can execute not only the vertex and fragment shading programs, but also the software rasteriation module which is mostly implemented by a individual hardware module in other GPU designs. Next, the thread-switching policy in our design is based on the non-preempt blocked scheduling. Normally, whether an instruction will be stalled cannot be detected until it enters the instruction-decode stage. In order to achieve zero-penalty thread switching, a single assistant bit will be padded to each instruction in a thread to tell if the next instruction in the same thread will be stalled or not. This mechanism can help achieve a speed-up of 1.4 in some benchmarks used in this thesis. The register file used in GPU processor is usually equipped with up to four access ports, such that it will occupy a significant portion of the entire GPU especially for muti-thread designs where the register set has to be duplicated by several copies. The implementation cost of the register file can be reduced by decreasing its access port number to two based on the proposed multi-bank approach in this thesis. Our experimental results show that this approach can help reduce the overall gate count by 26.12%. Finally, the rest of fixed-pipeline fragment operation is realized by an iterative time-sharing architecture in order to further save the silicon area. The overall gate count of the proposed GPU is 600K.

The purpose of this thesis is to develop a texture-based painterly shader that would render computer generated objects or scenes with strokes that are visually similar to paint media like watercolor, oil paint or dry media such as crayons, chalk, et cetera. This method would need an input scene in the form of three dimensional polygonal or NURBS meshes. While the structure of the meshes and the lighting in the scene would both play a crucial role in the final appearance of the scene, the painterly look will be imparted through a shader. This method, therefore, is essentially a rendering technique. Several modifiable parameters in the shader gives the user artistic freedom while overall introducing some amount of automation in the painterly rendering process.

With technology increasingly and the needs of high performance and multiple functionalities, power dissipation has be a bottleneck in microprocessors. And clock power is the most percentage of total power dissipation. In our thesis, we will provide an effective clock gating methodology that has not more overhead possibly to decrease total power dissipations based on SIMD 3D vertex shader. Except for classify all instructions according the instruction flow, we also consider the relationship of pipeline stage and are based on register bank to control execution units more flexibility. Using clock gating not only can decrease clock power, but also decrease the power of hardware modules succeed the registers with clock gating that be controlled. In our thesis, we will analysis which clock gating version is suitable because there is not definitely to disable the clock of all pipeline registers of all pipeline stages and hold all opportunities that can disable the clock. We will explain on experimental results and show the final low power version. With experimental results, the clock gating methodology that we bring can decrease almost 30% power with increase less than 2% area. And collection of instruction schedule algorithm for high performance that can decrease 41% energy at most. In new version of four vertexes execute sequentially, using clock gating can also decrease almost 10% power dissipation. And collection of instruction schedule algorithm for this version not only has better performance result but also can decrease 16% energy at most.

Vertex shader, one of the core parts in 3D graphics systems, is to speed up the operations of coordinate transformation and lighting in 3D graphics pipeline, and vector ALU is the key part of a vertex shader. This thesis proposes several unified architectures that integrate the floating-point vector arithmetic unit and special function unit in order to share some hardware resource. We propose three different architectures for the design of the unified vector ALU. The first architecture includes a single-instruction-multiple-data (SIMD) vector arithmetic unit, and uses table-based method with first-order approximation to calculate some special functions. The second architecture use higher-order approximation to reduce the table sizes and share the floating-point multipliers in the SIMD vector unit. The proposed third architecture has two copies of hardware that can compute two dot-product operations in parallel and thus increase the throughput of the matrix computation by a factor of two. Furthermore, the two dot-product units can be used to perform the interpolation for special function calculation.

In computer graphics technique, the 3D graphic pipeline flow has two processing modules: Geometry module and Rendering module. The geometry module supports vertex coordinate transformation, vertex lighting computation, backface-culling, pre-clipping, and clipping functions. Clipping module clips the outside part of objects by view volume boundaries. Adding clipping module into geometry module will make 3D graphics pipeline flow more efficiency. Due to the sequential parsing nature of clipping, it causes the challenges to implement clipping function in hardware design. This paper implements a dual-path clipping engine placed after the Vertex Shader in geometry module and supports OpenGL-ES 2.0 specification. With the clipping engine, it reduces the unnecessary operations in 3D graphics pipeline flow and makes the performance efficient. The pipelined and shared hardware design is proposed to improve the area cost and throughput of the interpolation operation in clipping engine. The two vertices in/out clipping method is proposed in this paper. Users have more different choices of clipping algorithms for hardware implementation with respect to the performance and hardware limitation.

In this thesis I look into how one can train and run an artificial neural network using Compute Shader and what kind of performance can be expected. An artificial neural network is a computational model that is inspired by biological neural networks, e.g. a brain. Finding what kind of performance can be expected was done by creating an implementation that uses Compute Shader and then compare it to the FANN library, i.e. a fast artificial neural network library written in C. The conclusion is that you can improve performance by training an artificial neural network on the compute shader as long as you are using non-trivial datasets and neural network configurations.

Detta arbete har undersökt hur mycket en volymetrisk eldeffekt med tillhörande fysiksimulering kan optimeras medan effekten samtidigt presterar tillfredställande. I bakgrunden ges en sammanfattning om eldteknikens historia. De begrepp som krävs för att förstå arbetet som helhet redogörs. I bakgrunden presenteras även den forskning som motiverar utförandet av arbetet. Bakgrunden följs av problemformuleringen med tillhörande metodbeskrivning. Problemformuleringen förklarar att optimering av en eldeffekt skall undersökas och då  eld är en mycket använd effekt. Metodbeskrivningen behandlar utförandet och förklarar att ett frågeformulär användes med en urvalsgrupp på 10 respondenter. I implementationen förklaras hur den utvecklade applikationen fungerar och vilka problem som påträffats under implementationen. Sedan följer utvärderingen som presenterar den data som samlats. Datan analyseras och intressanta slutsatser som antalet stickprov presenteras. I en avslutande diskussion presenteras vilken nytta samhället har av arbetet samt hur en fortsatt forskning kan se ut.

<p>To correctly reproduce the appearance of different objects in computer graphics applications, numerous lighting models have been proposed over the past several decades. These models are among the most important components in the modern graphics pipeline since they decide the final pixel color shown in the generated images. More physically valid parameters and functions have been introduced into recent models. These parameters expanded the range of materials that can be represented and made virtual scenes more realistic, but they also made the lighting models more complex and dependent on measured data.</p> <p>Artificial neural networks, or neural networks are famous for their ability to deal with complex data and to approximate arbitrary functions. They have been adopted by many data-driven approaches for computer graphics and proven to be effective. Furthermore, neural networks have also been used by the artists for creative works and proven to have the ability of supporting creation of visual effects, animation and computational arts. Therefore, it is reasonable to consider artificial neural networks as potential tools for representing lighting models. Since shaders are used for general-purpose computing, neural networks can be further combined with modern graphics pipeline using shader implementation. </p> <p>In this research, the possibilities of shader-based neural networks to be used as an alternative to traditional lighting models are explored. Fully connected neural networks are implemented in fragment shader to reproduce lighting results in the graphics pipeline, and trained in compute shaders. Implemented networks are proved to be able to approximate mathematical lighting models. In this thesis, experiments are described to prove the ability of shader-based neural networks, to explore the proper network architecture and settings for different lighting models. Further explorations of possibilities of manually editing parameters are also described. Mean-square errors and runtime are taken as measurements of success to evaluate the experiments. Rendered images are also reported for visual comparison and evaluation.</p>

Theoretical part of this project is focused on rendering of volumetric data. It compares and appraise individual methods and thus readers get a good basic knowledge of commonnest causes of problems. Texture Mapped Volume Rendering and Volume Ray-casting methods are described in detail and the latter method is used in implementation of graphic system designed in this thesis. Secondary goals of this work are usage of less powerful hardware for volume-rendering, methods of optimization and dynamic change of output quality.