I have the following vertex shader:
#version 330
layout (location = 0) in vec3 Position;
uniform mat4 gWVP;
out vec4 Color;
void main()
{
gl_Position = gWVP * vec4(Position, 1.0);
};
How can I get, for example, the third value of vec3? The first my thought was: "Maybe I can get it by multiplying this vector(Position) on something?" But I am not sure that something like "vertical vector type" exists. So, what is the best way? I need this value to set the color of the pixel.
A vertex shader receives a single vertex from the vertex stream and generates a single vertex to the output vertex stream. There must be a 1:1 mapping from input vertices to output vertices. Vertex shaders typically perform transformations to post-projection space, for consumption by the Vertex Post-Processing stage.
In the last assignment statement, gl_Position is the special built-in variable that is used in the vertex shader to give the coordinates of the vertex. gl_Position is of type vec4, requiring four numbers, because the coordinates are specified as homogeneous coordinates (Subsection 3.5. 3).
vec4 is a floating point vector with four components. It can be initialized by: Providing a scalar value for each component. Providing one scalar value. This value is used for all components.
A vertex shader receives its input data from a vertex attribute. But how does a fragment shader gets its data? Data is passed from shader to shader by using the in and out keywords. You create an output shader variable by using the out keyword.
There are at least 4 options:
x
, y
, z
, w
. This is mostly used for vectors that represent points/vectors. In your example, that would be Position.z
.r
, g
, b
, a
. This is mostly used for vectors that represent colors. In your example, you could use Position.b
, even though that would not be very readable. On the other hand, Color.b
would be a good option for the other variable.s
, t
, p
, q
. This is mostly used for vectors that represent texture coordinates. In our example, Position.p
would also give you the 3rd component.Position[2]
also gives he 3rd element.If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With