在 LibGDX 游戏中使用着色器叠加灯光答案

【问题标题】：Superimpose lights with shaders in LibGDX game在 LibGDX 游戏中使用着色器叠加灯光
【发布时间】：2015-01-30 19:57:24
【问题描述】：

我正在使用 Libgdx 制作回合制游戏。

我正在尝试通过在地图上添加蒙版并在战斗区域的每个单元格上添加地图灯来为战斗营造战争迷雾。

为此，我必须叠加灯光，但我不能。

比赛结果：

java 渲染代码：

//draw the light to the FBO
fbo.begin();
batch.setProjectionMatrix(cam.combined);
batch.setShader(defaultShader);
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);

batch.begin();
float lightSize = lightOscillate? (4.75f + 0.25f * (float)Math.sin(zAngle) + .2f*MathUtils.random()):5.0f;
//Draw light 1
batch.draw(light, 0, 0, lightSize, lightSize);

//Draw light 2
batch.draw(light, 2, 2, lightSize, lightSize);

batch.end();
fbo.end();

//draw the actual scene
Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
batch.setProjectionMatrix(cam.combined);
batch.setShader(finalShader);
batch.begin();
fbo.getColorBufferTexture().bind(1); //this is important! bind the FBO to the 2nd texture unit
light.bind(0); //we force the binding of a texture on first texture unit to avoid artefacts
            //this is because our default and ambiant shader dont use multi texturing...
            //youc can basically bind anything, it doesnt matter
tilemap.render(batch, dt);
batch.end();

片段着色器代码：

varying LOWP vec4 vColor;
varying vec2 vTexCoord;

//texture samplers
uniform sampler2D u_texture; //diffuse map
uniform sampler2D u_lightmap;   //light map

//additional parameters for the shader
uniform vec2 resolution; //resolution of screen
uniform LOWP vec4 ambientColor; //ambient RGB, alpha channel is intensity 

void main() {
   vec4 diffuseColor = texture2D(u_texture, vTexCoord);
   vec2 lighCoord = gl_FragCoord.xy / resolution.xy;
   vec4 light = texture2D(u_lightmap, lighCoord);

   vec3 ambient = ambientColor.rgb * ambientColor.a;
   vec3 intensity = ambient + light.rgb;
    vec3 finalColor = diffuseColor.rgb * intensity;

   gl_FragColor = vColor * light; //vec4(finalColor, diffuseColor.a);
}

【问题讨论】：

您似乎需要启用 Alpha 混合。
我尝试在 batch.begin() 和 create() 方法之后添加Gdx.gl20.glEnable(GL20.GL_BLEND); Gdx.gl20.glBlendFunc(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA);，但它什么也没做。

标签： opengl libgdx shader light

【解决方案1】：

我找到了解决方案。必须启用 Alpha 混合。

这里是正确的渲染代码：

public void render() {
    final float dt = Gdx.graphics.getRawDeltaTime();

    Gdx.gl.glClearColor(0f,0f,0f,1f);
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);   

    batch.setBlendFunction(GL20.GL_SRC_ALPHA, GL20.GL_ONE);

    //draw the light to the FBO
    fbo.begin();
    Gdx.gl.glClearColor(0f,0f,0f,0f);
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
        batch.setProjectionMatrix(cam.combined);
        batch.setShader(defaultShader);

        batch.begin();
        float lightSize = lightOscillate? (4.75f + 0.25f * (float)Math.sin(zAngle) + .2f*MathUtils.random()):5.0f;
        //Draw light 1
        batch.draw(light, 0, 0, lightSize, lightSize);

        //Draw light 2
        batch.draw(light, 2, 2, lightSize, lightSize);

        batch.end();
    fbo.end();

    batch.setBlendFunction(GL20.GL_SRC_ALPHA, GL20.GL_ONE_MINUS_SRC_ALPHA);

    //draw the actual scene
    Gdx.gl.glClear(GL20.GL_COLOR_BUFFER_BIT);
    batch.setProjectionMatrix(cam.combined);
    batch.setShader(finalShader);
    batch.begin();
    fbo.getColorBufferTexture().bind(1); //this is important! bind the FBO to the 2nd texture unit
    light.bind(0); //we force the binding of a texture on first texture unit to avoid artefacts
                   //this is because our default and ambiant shader dont use multi texturing...
                   //youc can basically bind anything, it doesnt matter
    tilemap.render(batch, dt);
    batch.end();
}

【讨论】：