What is varying GLSL?
GLSL also allows user defined varying variables. These must be declared in both the vertex and fragment shaders, for instance: varying float intensity; A varying variable must be written on a vertex shader, where we compute the value of the variable for each vertex.
What is varying in shader?
varying variables contain data shared from a vertex shader to a fragment shader. The variable must be written in the vertex shader and the read-only value in the fragment shader is then interpolated from the vertices which make up the fragment.
Is GLSL optimized?
1 Answer. GLSL compilers are very conservative on floating point optimizations. You cannot be sure for any particular optimization. The rule of thumb is: optimize whatever you can and don’t hope for any help from a GLSL compiler.
What is GLSL Highp?
highp. The qualifier highp is used to specify the highest available precision for a variable. The variable has to be an integer or a floating point scalar or a vector or matrix based on these types. The precision qualifier precedes the type in the variable declaration.
What is GLSL attribute?
Attributes are GLSL variables which are only available to the vertex shader (as variables) and the JavaScript code. Attributes are typically used to store color information, texture coordinates, and any other data calculated or retrieved that needs to be shared between the JavaScript code and the vertex shader.
What are varying variables?
Varying variables are vertex shader output. Also they’re fragment shader input. All you need to do is set vertex output varying values, and GPU will smoothly interpolate these values between pixels, and pass this interpolated data into fragment shader input data.
How do I optimize GLSL?
One way to speed up GLSL code, is by marking some variables constant at compile-time. This way the compiler may optimize code (e.g. unroll loops) and remove unused code (e.g. if hard shadows are disabled). The drawback is that changing these constant variables requires that the GLSL code is compiled again.
What is Swizzling in GLSL?
A common feature of shader languages like GLSL is components swizzling. This involves being able to select which components of a vector are used and in what order. For example, “variable. x”, “variable.
What does uniform mean in GLSL?
A uniform is a global Shader variable declared with the “uniform” storage qualifier. These act as parameters that the user of a shader program can pass to that program. This makes them unlike shader stage inputs and outputs, which are often different for each invocation of a shader stage.
What is the default interpolation qualifier in GLSL?
noperspective: performs a linear interpolation in window space. The default interpolation qualifier is smooth when no qualifier is present. Let’s see in practice how these qualifiers affect the rendering. I used GLSL Hacker to quickly code the demo and play with GLSL shaders.
How are the varying variables used in GLSL?
GLSL varying variables Above you see a square where each corner has a color and the rest of the square gets its color by interpolating between these corners. The square is drawn using WebGL. There is one draw call, with four vertices: the four corners.
How are the colors interpolated in WebGL?
The square is drawn using WebGL. There is one draw call, with four vertices: the four corners. Each vertex is assigned a color attribute , and WebGL interpolates between these colors using a varying variable.
Which is not interpolated in the OpenGL spec?
The OpenGL spec/wiki says: flat: the value is not interpolated. The value given to the fragment shader is the value from the Provoking Vertex for that primitive. smooth: performs a perspective correct interpolation.