shader

I've seen this pseudo-random number generator for use in shaders referred to here and there around the web : float rand(vec2 co){ return fract(sin(dot(co.xy ,vec2(12.9898,78.233))) * 43758.5453); } It's variously called "canonical", or "a one-liner I found on the web somewhere". What's the origin of this function? Are the constant values as arbitrary as they seem or is there some art to their selection? Is there any discussion of the merits of this function? EDIT: The oldest reference to this function that I've come across is this archive from Feb '08 , the original page now being gone from

Trying to send an array of integer to a compute shader, sets an arbitrary value to each integer and then reads back on CPU/HOST. The problem is that only the first element of my array gets updated. My array is initialized with all elements = 5 in the CPU, then I try to sets all the values to 2 in the Compute Shader: C++ Code: this->numOfElements = std::vector<int> numOfElements; //num of elements for each voxel //Set the reset grid program as current program glUseProgram(this->resetGridProgHandle); //Binds and fill the buffer glBindBuffer(GL_SHADER_STORAGE_BUFFER, this->counterBufferHandle);

Seems like it's not as simple as RGB1*A1 + RGB2*A2...how are values clipped? Weighted? Etc. And is this a context-dependent question? Are there different algorithms, that produce different results? Or one standard implementation? I'm particularly interested in OpenGL-specific answers, but context from other environments is useful too. I don't know about OpenGL, but one pixel of opacity A is usually drawn on another pixel like so: result.r = background.r * (1 - A) + foreground.r * A result.g = background.g * (1 - A) + foreground.g * A result.b = background.b * (1 - A) + foreground.b * A Repeat

DX11中提供vs和ps后的又一支持直接gpu计算的Compute Shader,可以看得出物理加速不再是只属于n卡,而且gpu通用计算的道路会越发成熟,下面做下标记,下次翻译 // from DX11 SDK and gamedev Compute shaders are basically the same as any other shader ... pixel shader for example. Just like the pixel shader is envoked for each pixel, the compute shader is envoked for each "thread". A thread is a generic and independent execution entity that doesn't really require any sort of geometry. All you have to do now is to dispatch a number of threads, and your shader will be executed for each of these threads. In DirectX, these threads are organized into "groups". You have X

I am splitting a texture 1024 x 1024 over 32x32 tiles * 32, Im not sure if its possible to share the texture with an offset or would i need to create a new texture for each tile with the offset.. to create the offset i am using a uniform value = 32 * i and updating the uniform through each loop instance of creating tile, all the tiles seem to be the same offset? as basically i wanting an image to appear like its one image not broken up into little tiles.But the current out-put is the same x,y-offset on all 32 tiles..Im using the vertex-shader with three.js r71... Would i need to create a new

I'm learning OpenGL ES 2.0 and I'd like to create an App to better understand how it works. The App has a set of filter that the user can apply on images (I know, nothing new :P). One of this filter takes two images and a mask and it mixes the two images showing them through the mask (here an image to better explain what I want to obtain) At the moment I'm really confused and I don't know where to start to create this effect. I can't understand wether I have to work with multiple textures and multiple FrameBuffers or I can just work with a single shader. Do you have any hint to help me in