Question

我正在尝试使这两个着色器正常工作。我什至让片段着色器显示红色而不是RGB数据，只是看它们是否在工作。但是链接过程失败。

public static final String videoVertex =
    "#version 300 es\n"+
    "precision mediump float;\n"+
    "layout (location = 0) in vec3 aPos;\n" +
    "layout (location = 1) in vec2 aTexCoord;\n" +
    "\n" +
    "out vec2 TexCoord;\n" +
    "\n" +
    "void main()\n" +
    "{\n" +
    "    gl_Position = vec4(aPos, 1.0);\n" +
    "    TexCoord = vec2(aTexCoord.x, aTexCoord.y);\n" +
    "}\n";

public static final String videoFragment =
    "#version 300 es\n"+
    "uniform float alpha;\n" +
    "uniform sampler2D sampler;\n"+
    "\n" +
    "in vec2 TexCoord;\n" +
    "out vec4 FragColor;\n" +
    "void main()\n" +
    "{\n" +
    "    vec4 rgba;\n" +
    "    rgba.rgb = texture(sampler, TexCoord).rgb;\n" +
    "    rgba.a = 1;\n" +
    "    FragColor = vec4(1.0f,0,0,1.0f);\n" +
    "    //FragColor = rgba;\n" +
    "}\n";

mProgram = GLES20.glCreateProgram();

int vertexShader = SimpleGLRenderer.loadShader(GLES20.GL_VERTEX_SHADER, videoVertex);
int fragmentShader = SimpleGLRenderer.loadShader(GLES20.GL_FRAGMENT_SHADER, videoFragment);

int[] compiled = new int[1];

GLES20.glAttachShader(mProgram, vertexShader);
GLES20.glGetShaderiv(vertexShader, GLES20.GL_COMPILE_STATUS, compiled, 0);
Log.d(TAG, "### vertex shader compilation: " + Arrays.toString(compiled));

GLES20.glAttachShader(mProgram, fragmentShader);
GLES20.glGetShaderiv(vertexShader, GLES20.GL_COMPILE_STATUS, compiled, 0);
Log.d(TAG, "### fragment shader compilation: " + Arrays.toString(compiled));

GLES20.glLinkProgram(mProgram);
int[] link = new int[1];
GLES20.glGetProgramiv(mProgram, GLES20.GL_LINK_STATUS, link, 0);
if (link[0] <= 0) {
    Log.d("### Load Program", "Linking Failed: " + link[0]);
}

这是我得到的输出：

2020-07-11 01:57:17.318 22963-23004/com.example.mediacodecdecoderexample D/VideoRenderer: ### vertex shader compilation: [1]
2020-07-11 01:57:17.318 22963-23004/com.example.mediacodecdecoderexample D/VideoRenderer: ### fragment shader compilation: [1]
2020-07-11 01:57:17.318 22963-23004/com.example.mediacodecdecoderexample D/### Load Program: Linking Failed: 0

如您所见，编译进行得很好，但没有链接。怎么可能呢？

Answer 1

您的片段着色器无法编译，因为在OpenGL ES 3.0中，不允许将整数常量分配给浮点变量。您必须分配一个浮点数：

~~rgba.a = 1;~~

rgba.a = 1.0;

此外，缺少用于浮点类型的精度限定符。实例：

precision mediump float;

请参见OpenGL ES Shading Language 3.00 Specification - 4.5.4 Default Precision Qualifiers：

对于浮点类型，片段语言没有默认的精度限定符。因此，对于浮点，浮点向量和矩阵变量声明，声明必须包含精度限定符，或者必须事先声明默认的浮点精度。

简单的Android着色器可编译，但链接失败

1 个答案: