Vertex shaders and fragment shaders are distinct stages in the graphics pipeline. Vertex shaders process individual vertices, handling tasks like transformations, skinning, and per-vertex lighting. Fragment shaders, on the other hand, operate on fragments generated by rasterization, determining their final color and depth values.
Vertex shaders are used for operations such as :
1. Transforming vertex positions from model space to clip space.
2. Calculating per-vertex lighting or passing data to be interpolated across fragments.
Example : Transform a vertex position using a model-view-projection matrix.
vec4 transformedPosition = u_mvpMatrix * a_position;?
Fragment shaders are used for operations such as :
1. Texturing – sampling textures and combining them with fragment colors.
2. Per-pixel lighting – calculating lighting based on interpolated normals and positions.
3. Post-processing effects – modifying final pixel colors based on various factors.
Example : Calculate Phong shading with diffuse and specular components.
vec3 normal = normalize(v_normal);
vec3 lightDir = normalize(u_lightPosition - v_position);
float diffIntensity = max(dot(normal, lightDir), 0.0);
vec3 reflectDir = reflect(-lightDir, normal);
vec3 viewDir = normalize(-v_position);
float specIntensity = pow(max(dot(reflectDir, viewDir), 0.0), u_shininess);
vec3 finalColor = (u_diffuseColor * diffIntensity) + (u_specularColor * specIntensity);?
