You’re right, the vertex shader is executed for each vertex. A vertex is composed by of or several attributes (positions, normals, texture coordinates etc.). On the CPU side when you create your VAO, you describe each attribute by saying “this data in this buffer will be attribute 0, the data next to it will be … Read more
I’m going to argue that the most efficient approach will be in drawing a single “full-screen” triangle. For a triangle to cover the full screen, it needs to be bigger than the actual viewport. In NDC (and also clip space, if we set w=1), the viewport will always be the [-1,1] square. For a triangle … Read more
Is GLSL ES 2 a totally separate language, or a special version of GLSL? Every version of GLSL is ultimately a “totally separate language;” some aren’t even backwards compatible with previous versions. However, the ES variation of GLSL is even moreso. Think of it as a fork of desktop GLSL. A fork of GLSL from … Read more
From the OpenGL ES Shading Language reference: highp – 16-bit, floating point range: −262 to 262, integer range: −216 to 216 mediump – 10 bit, floating point range: −214 to 214, integer range: −210 to 210 lowp – 8 bit, floating point range: −2 to 2, integer range: −28 to 28 In OpenGL ES 3 … Read more
It’s a catch-all for multiple types. From the specification section 8 When the built-in functions are specified below, where the input arguments (and corresponding output) can be float , vec2 , vec3 , or vec4 , genType is used as the argument. Where the input arguments (and corresponding output) can be int , ivec2 , … Read more
Yes, texture2D() is deprecated as of (at least) OpenGL 3.3; see page 99 of the 3.30 GLSL specification. It will continue to be supported in OpenGL compatibility profiles to avoid breaking existing code, but its usage in new code is strongly discouraged. EDIT: The details are slightly different for OpenGL ES, but the end result … Read more
Quoting from the first source that I could find (PDF), at the top of §8.3 Common Functions, page 132: These all operate component-wise. The description is per component. Nearly all the functions that operator on vectors but really only make sense for a scalar operate component-wise. (This includes abs, sign, floor, trunc, round, roundEven, ceil, … Read more
I am the author of the second implementation. It has always behaved correctly for me, but you wrote 2.9 / 6.9 instead of 2.0 / 6.0. Since you target GLSL, you should use conversion routines that are written with the GPU in mind: // All components are in the range [0…1], including hue. vec3 rgb2hsv(vec3 … Read more
I’d like to extent on BDL’s answer. It is not only about the perspective interpolation. It is also about the clipping. The space the value gl_Position is supposed to be provided in is called clip space, and this is before the division by w. The (default) clip volume of OpenGL is defined in clip space … Read more
The first thing you need to understand about shading_language_include is what it isn’t. It is not “I #include a file from the disk.” OpenGL doesn’t know what files are; it has no concept of the file system. Instead, you must pre-load all of the files you might want to include. So you have a shader … Read more