QOpenGLShader::link: error: fragment shader lacks `main'
时间: 2023-07-04 08:31:00 浏览: 69
这个错误是因为你的片段着色器缺少了 main 函数。在OpenGL中,每个着色器程序都需要有一个main函数作为入口点。请确保你的片段着色器中有一个名为main的函数,并且函数签名正确。例如:
```
#version 330 core
out vec4 FragColor;
void main()
{
FragColor = vec4(1.0f, 0.5f, 0.2f, 1.0f);
}
```
如果你的代码中已经有了main函数,那么请检查函数签名是否正确,例如是否缺少参数或返回类型等。如果还有问题,请提供更多的代码和错误信息,以便我可以更好地帮助你。
相关问题
Must have a compiled fragment shader attached:
这是一个错误信息,通常出现在使用OpenGL或WebGL等图形库时。它意味着你需要编译一个片段着色器(fragment shader)并将其附加到你的程序中。片段着色器是一种编程语言,用于创建渲染图像的特定效果,例如颜色、光照和纹理。你需要确保你的代码包含一个有效的片段着色器,并且已经成功编译和链接到你的程序中。如果你需要更多帮助,请提供更多上下文或代码示例。
Unity Shader:Projective Texture Mapping
Projective texture mapping in Unity Shader is a technique used to project a texture onto an object in a way that simulates the effect of a slide projector. It can be used to create various effects like projecting a spotlight texture onto a surface, projecting a decal onto a curved surface, or creating a shadow map for an object.
To implement projective texture mapping in Unity Shader, you need to use a combination of vertex and fragment shaders. The vertex shader calculates the projective transformation matrix, which is used to transform the texture coordinates in the fragment shader. The fragment shader samples the texture and applies it to the object's surface.
Here's a simple example of a vertex shader that calculates the projective transformation matrix:
```
Shader "Custom/ProjectiveTextureMapping"
{
Properties
{
_MainTex ("Texture", 2D) = "white" {}
_Projector ("Projector", 3D) = "" {}
}
SubShader
{
Pass
{
CGPROGRAM
#pragma vertex vert
#pragma fragment frag
uniform sampler2D _MainTex;
uniform float4x4 unity_Projector;
float4x4 unity_ObjectToWorld;
struct appdata
{
float4 vertex : POSITION;
float3 normal : NORMAL;
float2 uv : TEXCOORD0;
};
struct v2f
{
float2 uv : TEXCOORD0;
float4 vertex : SV_POSITION;
};
v2f vert (appdata v)
{
v2f o;
o.vertex = UnityObjectToClipPos(v.vertex);
o.uv = mul(unity_Projector, v.vertex).xy;
return o;
}
fixed4 frag (v2f i) : SV_Target
{
return tex2D(_MainTex, i.uv);
}
ENDCG
}
}
}
```
In this example, the `_MainTex` property is the texture to be projected, and the `_Projector` property is the object that will project the texture. The `unity_Projector` variable is a matrix that transforms the texture coordinates from object space to clip space. The `vert` function calculates the transformed texture coordinates and passes them to the fragment shader in the `v2f` struct.
The fragment shader simply samples the texture using the transformed texture coordinates and returns the color.
You can use this shader by assigning it to a material and setting the `_MainTex` and `_Projector` properties to appropriate textures and objects, respectively.