The OpenGL wiki gives a good definition: A Shader is a user-defined program designed to run on some stage of a graphics processor. History lesson In the past, graphics cards were non-programmable pieces of silicon which performed a set of fixed algorithms: inputs: 3D coordinates of triangles, their colors, light sources output: a 2D image … Read more
Each shader stage has its own frequency of invocations. I will use the OpenGL terminology, but D3D works the same way (since they’re both modelling the same hardware relationships). Vertex Shaders These are the second most complicated. They execute once for every input vertex… kinda. If you are using non-indexed rendering, then the ratio is … Read more
A highly optimized shader-based approach for performing a nine-hit Gaussian blur was presented by Daniel Rákos. His process uses the underlying interpolation provided by texture filtering in hardware to perform a nine-hit filter using only five texture reads per pass. This is also split into separate horizontal and vertical passes to further reduce the number … Read more
You want to render a clipped surface as if it were a solid — i.e., not hollow. You can achieve that effect with MeshPhongMaterial — or any three.js material for that matter — with a simple hack to the material shader. material.onBeforeCompile = function( shader ) { shader.fragmentShader = shader.fragmentShader.replace( ‘#include <output_fragment>’, ` vec3 backfaceColor … Read more
Sorry, it hasn’t been replaced with anything. The first idea coming to my mind for emulating it would be the geometry shader. You feed the geometry shader with a line, compute its screen space length and based on that you generate a variable number of sub lines between its start and end vertex. EDIT: Perhaps … Read more
It’s hardware-dependent. For PowerVR hardware, and other GPUs that use tile-based rendering, using discard means that the TBR can no longer assume that every fragment drawn will become a pixel. This assumption is important because it allows the TBR to evaluate all the depths first, then only evaluate the fragment shaders for the top-most fragments. … Read more
I don’t know if you solved your problem. I used your code and I solved in this mode. public class MyRenderer implements Renderer{ public static final int recWidth = Costanti.recWidth; public static final int recHeight = Costanti.recHeight; private static final int U_INDEX = recWidth*recHeight; private static final int V_INDEX = recWidth*recHeight*5/4; private static final int … Read more
Rendering outlines, unless you render only a dozen characters total, remains a “no go” due to the number of vertices needed per character to approximate curvature. Though there have been approaches to evaluate bezier curves in the pixel shader instead, these suffer from not being easily antialiased, which is trivial using a distance-map-textured quad, and … Read more
three.js was designed to be easy to use, not easy to modify. This may change in the future… You need to set the material.defines like so: var defines = {}; defines[ “USE_MAP” ] = “”;. Then specify defines in the material constructor. var material = new THREE.ShaderMaterial({ name: “TerrainShader”, defines : defines, uniforms : shaderUniforms, … Read more
The short answer is to load the camera image channels (Y,UV) into textures and draw these textures onto a Mesh using a custom fragment shader that will do the color space conversion for us. Since this shader will be running on the GPU, it will be much faster than CPU and certainly much much faster … Read more