GLSL Shader Coding Style

• Indentation is 2 spaces

• When functions are multiple lines, each argument does not have to be on its own line

• Interface Blocks should be used to pass data between shader stages. The interface blocks are matched based on the struct name instead of the variable name, which makes logical naming a lot easier. By using the name Data for all Interface blocks, we make sure that they always work and make it easy to remember.

Old:

// vertex
in vec3 in_position;
in vec3 in_bvLumAbsMag;
in vec3 in_velocity;
in float in_speed;

out vec3 vs_bvLumAbsMag;
out vec3 vs_velocity;
out float vs_speed;

// geometry
layout(points) in;
in vec3 vs_bvLumAbsMag[];
in vec3 vs_velocity[];
in float vs_speed[];

layout(triangle_strip, max_vertices = 4) out;
out vec3 vs_position;
out vec2 texCoords;
flat out float ge_bv;
flat out vec3 ge_velocity;
flat out float ge_speed;
flat out float gs_screenSpaceDepth;

// fragment
in vec3 vs_position;
in vec2 texCoords;
flat in float ge_bv;
flat in vec3 ge_velocity;
flat in float ge_speed;
flat in float gs_screenSpaceDepth;

New:

// vertex
layout(location = 0) in vec3 in_position;
layout(location = 1) in vec3 in_bvLumAbsMag;
layout(location = 2) in vec3 in_velocity;
layout(location = 3) in float in_speed;
layout(location = 4) in float in_otherData;

out Data {
  vec3 bvLumAbsMag;
  vec3 velocity;
  float speed;
  float otherData;
} out_data;

// geometry
layout(points) in;
in Data {
  vec3 bvLumAbsMag;
  vec3 velocity;
  float speed;
  float otherData;
} in_data[];

layout(triangle_strip, max_vertices = 4) out;
out Data {
  vec3 position;
  flat vec3 velocity;
  vec2 texCoords;
  flat float bv;
  flat float speed;
  flat float otherData;
  flat float screenSpaceDepth;
} out_data;

// fragment
in Data {
  vec3 position;
  flat vec3 velocity;
  vec2 texCoords;
  flat float bv;
  flat float speed;
  flat float otherData;
  flat float screenSpaceDepth;
} in_data;

Interface blocks can’t be used to transfer data into a vertex shader or out of a fragment shader. The naming convention is that data flowing into a shader is prefixed with in_ and data flowing out of a shader is prefixed with out_

• No underscores are allowed in variable names apart from the in_ and out_ prefixes to make it immediately obvious when we are manipulating such data.

• The order in the top of a shader file is:

  1. Includes

  2. in variables

  3. out variable

  4. uniforms

  5. constants

  6. Two empty lines

  7. Other functions

  8. Two empty lines (if there are no other functions, this step is skipped)

  9. main or getFragment function