Variable from vertex to pixel shader.

[NoreoAlles]

Hello i want to compute the normal to lighting direction dotproduct inside of my vertex shader and then have this value used in the pixel shader for simple lighting but i cant seem to find a way to do this. On stackoverflow they suggest modifying the geometry shader inbetween the two to pass the variable but i dont know.
Tldr: How do i get float computed inside of vertex shader to fragment shader?

[NoreoAlles]

Hello i want to compute the normal to lighting direction dotproduct inside of my vertex shader and then have this value used in the pixel shader for simple lighting but i cant seem to find a way to do this. On stackoverflow they suggest modifying the geometry shader inbetween the two to pass the variable but i dont know.
Tldr: How do i get float computed inside of vertex shader to the the fragment shader?

[marclurr]

Should be something like this. In your vertex shader

Code: Select all

out float myval

vec4 position( mat4 transform_projection, vec4 vertex_position ) {
    myval = ...
}

In your fragment shader

Code: Select all

in float myval

vec4 effect(vec4 color, Image tex, vec2 texture_coords, vec2 screen_coords) {
    ... use myval ...
}

The value will be linearly interpolated by opengl.

[NoreoAlles]

Should be something like this. In your vertex shader

Code: Select all

out float myval

vec4 position( mat4 transform_projection, vec4 vertex_position ) {
    myval = ...
}

In your fragment shader

Code: Select all

in float myval

vec4 effect(vec4 color, Image tex, vec2 texture_coords, vec2 screen_coords) {
    ... use myval ...
}

The value will be linearly interpolated by opengl.

Ok thank you, so the in and out keywords are used for that.