How to implement image stroke function???

[lsq51201314]

Operating System

• Windows
• macOS
• Linux
• FreeBSD
• OpenBSD
• Android
• iOS
• Nintendo Switch
• PlayStation 5
• Xbox
• Web Browsers

What feature would you like to be added?

Most scenes in the game, such as when NPCS are selected, are highlighted with white Outlines

#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec2 aTexCoords;

uniform mat4 uProjection;
uniform mat4 uView;

out vec2 fTexCoords;

void main()
{
    fTexCoords = aTexCoords;
    gl_Position = uProjection * uView * vec4(aPos, 1.0);
} 

#version 330 core
uniform sampler2D TEX_SAMPLER;

in vec2 fTexCoords;

const float lineWidth = 0.005;
const vec3  lineColor = vec3(1.0, 1.0, 1.0);
const float transparen = 1.0;

void main() 
{
    vec4 texColor = texture2D(TEX_SAMPLER,fTexCoords);
    // //透明
    // if (texColor.a != 0.0){
    //     texColor.a = transparen; 
    // } 
    //描边
    if (texColor.a == 0.0){
        float a = 
            texture2D(TEX_SAMPLER, vec2(fTexCoords.x + lineWidth, fTexCoords.y)).a +
			texture2D(TEX_SAMPLER, vec2(fTexCoords.x, fTexCoords.y - lineWidth)).a +
			texture2D(TEX_SAMPLER, vec2(fTexCoords.x - lineWidth, fTexCoords.y)).a +
			texture2D(TEX_SAMPLER, vec2(fTexCoords.x, fTexCoords.y + lineWidth)).a;

		if (texColor.a < 1.0 && a > 0.0)
			texColor = vec4(lineColor,transparen);
        else 
            discard;
    }
    // //圆形
    // vec2 center = vec2(0.5,0.5);
    // float radius = 0.4;
    // float res = sqrt(pow((fTexCoords.x - center.x),2.0)+pow((fTexCoords.y - center.y),2.0));  
    // if(res > radius) {
    //     discard;    
    // }  
    gl_FragColor = texColor;
}    

Why is this needed?

No response

[lsq51201314]

 //着色器测试
opts := &ebiten.DrawRectShaderOptions{}
opts.Uniforms = make(map[string]interface{})
opts.Uniforms["OutLine"] = []int32{1}                      //描边
opts.Uniforms["LineWidth"] = []float32{0.001}              //线宽（左上角有问题，0.001可消除）
opts.Uniforms["LineColor"] = []float32{1.0, 1.0, 1.0, 1.0} //白色

opts.Images[0] = i.image
w, h := i.GetSize()
screen.DrawRectShader(w, h, i.shader, opts)

package main

var OutLine int
var LineWidth float
var LineColor vec4

func Fragment(dstPos vec4, srcPos vec2, color vec4) vec4 {
	col := imageSrc0UnsafeAt(srcPos).rgba
	if OutLine == 1 && col.a == 0.0 {
        a := imageSrc0UnsafeAt(vec2(srcPos.x + LineWidth, srcPos.y)).a +
			imageSrc0UnsafeAt(vec2(srcPos.x, srcPos.y - LineWidth)).a +
			imageSrc0UnsafeAt(vec2(srcPos.x - LineWidth, srcPos.y)).a +
			imageSrc0UnsafeAt(vec2(srcPos.x, srcPos.y + LineWidth)).a
		if (a > 0.0){
			col = vec4(LineColor.r,LineColor.g,LineColor.b,1.0)
		}
	}  
    return col * LineColor.a
}