Vertex and fragment
- Game Development course
- Advanced
- Lesson 5/71
- 4 min
Learn the roles of vertex and fragment functions.
The Role of the Vertex Shader
The Vertex Shader is the first programmable stage of the graphics pipeline. It executes once for every vertex of a 3D object, converting vertices from local model space to screen projection space (MVP transformation).
#pragma vertex vert
v2f vert (appdata v)
{
v2f o;
o.vertex = UnityObjectToClipPos(v.vertex);
o.uv = v.uv;
return o;
}Waving flags, wind-bent foliage, or character mesh deformations are produced by altering positions in the vertex shader stage.
Fragment Shader and Pixel Coloring
After vertices are processed, the rasterizer stage breaks the surface into screen pixels (fragments). Then the Fragment Shader runs to compute the final RGBA color for each individual pixel.
#pragma fragment frag
fixed4 frag (v2f i) : SV_Target
{
fixed4 col = tex2D(_MainTex, i.uv);
return col;
}Texture sampling, bloom effects, fog, and color grading are computed in the fragment shader stage and projected onto the display.
Practice Vertex and fragment pipeline
Define a Start method. Inside, declare int vertexSayisi = 4; and print "Kose sayisi: " + vertexSayisi to the console.
Starter code
using UnityEngine;
public class PipelineLogger : MonoBehaviour
{
// Start icinde vertexSayisi tanimla ve yazdir
}Sample solution
using UnityEngine;
public class PipelineLogger : MonoBehaviour
{
void Start()
{
int vertexSayisi = 4;
Debug.Log("Kose sayisi: " + vertexSayisi);
}
}Expected output
Kose sayisi: 4
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 Which shader stage is responsible for transforming vertex points of a 3D object from model space to screen projection space?
- Fragment Shader
- Vertex Shader Correct answer
- Audio Mixer
- Collider2D
Explanation: Position transformation of vertex points and geometric mesh deformations are executed in the Vertex Shader stage.
2 Fragment directive
#pragma ____ frag#pragma fragment fragExplanation: The '#pragma fragment' directive is used to register the fragment shader function with the compiler.
3 Pipeline concepts
| Term | Meaning |
|---|---|
Vertex Shader |
Transforms vertex positions |
Rasterizer |
Discretizes geometry into fragments |
Fragment Shader |
Computes pixel colors |
SV_Target |
Semantic for final color output |