OpenGL ES 2.0 / GLSL未呈现数据（Kotlin）

Question

我正在尝试使用GLES 2/3实现基本的着色程序，并已将各种教程中的代码拼凑而成。对我来说，一切看起来都正确，并且可以正常编译，但是屏幕上没有任何显示。

直到我添加了法线和光照位置数据，它都表现良好，然后它破裂了，我仍无法找到解决它的方法。

谁能看到这里有什么问题吗？

class MyRenderer:GLSurfaceView.Renderer{

    var glProgram = -1
    var uMV       = -1
    var uMVP      = -1
    var uLightPos = -1
    var aPosition = -1
    var aNormal   = -1
    var aColor    = -1

    val verts = arrayOf(0f,1f,0f, -1f,0f,0f,  1f,0f,0f)
    val vBuf: FloatBuffer = allocateDirect(verts.size*4).order(nativeOrder()).asFloatBuffer()
    val norms = arrayOf(0f,0f,-1f,  0f,0f,-1f,  0f,0f,-1f)
    val nBuf: FloatBuffer = allocateDirect(norms.size*4).order(nativeOrder()).asFloatBuffer()

    override fun onSurfaceCreated(g:GL10,c:EGLConfig) {
        glClearColor(0f,0f,0f,1f)
        glClearDepthf(1f)
        glClear(GL_COLOR_BUFFER_BIT or GL_DEPTH_BUFFER_BIT)

        glProgram = glCreateProgram()

        val vShader = glCreateShader(GL_VERTEX_SHADER)
        glShaderSource(vShader,"#version 100\n                    " +
            "uniform   mat4 u_mvMat;                              " +
            "uniform   mat4 u_mvpMat;                             " +
            "uniform   vec3 u_LightPos;                           " +
            "attribute vec4 a_Position;                           " +
            "attribute vec3 a_Normal;                             " +
            "attribute vec4 a_Color;                              " +
            "varying   vec4 v_Color;                              " +
            "void main(){                                         " +
            "   vec3 vertex = vec3(u_mvMat*a_Position);           " +
            "   vec3 normal = vec3(u_mvMat*vec4(a_Normal,0.0));   " +
            "   vec3 lightVector = normalize(u_LightPos-vertex);  " +
            "   float distance = length(u_LightPos-vertex);       " +
            "   float diffuse = max(dot(normal,lightVector),0.1)  " +
            "                   / (1.0+distance*distance/4.0);    " +
            "   v_Color = a_Color*diffuse;                        " +
            "   gl_Position = u_mvpMat*a_Position;}               " )
        glCompileShader(vShader)
        glAttachShader(glProgram,vShader)

        val fShader = glCreateShader(GL_FRAGMENT_SHADER)
        glShaderSource(fShader,"#version 100\n                    " +
            "precision mediump float;                             " +
            "varying vec4 v_Color;                                " +
            "void main(){                                         " +
            "   gl_FragColor = v_Color;}                          " )
        glCompileShader(fShader)
        glAttachShader(glProgram,fShader)

        glLinkProgram(glProgram)
        glUseProgram(glProgram)

        uMVP      = glGetUniformLocation(glProgram,"u_mvpMat")
        uMV       = glGetUniformLocation(glProgram,"u_mvMat")
        uLightPos = glGetUniformLocation(glProgram,"u_LightPos")
        aPosition = glGetAttribLocation (glProgram,"a_Position")
        aNormal   = glGetAttribLocation (glProgram,"a_Normal")
        aColor    = glGetAttribLocation (glProgram,"a_Color")

        glVertexAttribPointer(aPosition,4,GL_FLOAT,false,3*4,vBuf)
        glEnableVertexAttribArray(aPosition)
        glVertexAttribPointer(aNormal,4,GL_FLOAT,false,3*4,nBuf)
        glEnableVertexAttribArray(aNormal)

        val modelM = FloatArray(16)
        setIdentityM(modelM,0)
        val viewM = FloatArray(16)
        setLookAtM(viewM,0,  0f,0f,-5f,  0f,0f,0f,  0f,0f,1f)
        val projM = FloatArray(16)
        frustumM(projM,0, -2f,2f, 1f,-1f, 1f,50f)
        val mvM = FloatArray(16)
        multiplyMM(mvM,0,viewM,0,modelM,0)
        glUniformMatrix4fv(uMV,1,false,mvM,0)
        val mvpM = FloatArray(16)
        multiplyMM(mvpM,0,projM,0,mvM,0)
        glUniformMatrix4fv(uMVP,1,false,mvpM,0)

        glUniform3v(uLightPos,-1f,-10f,-1f)

        glVertexAttribI4i(aColor,1,1,1,1)
        glDrawArrays(GL_TRIANGLES,0,verts.size/3)
    }
    override fun onSurfaceChanged(g:GL10,w:Int,h:Int){}
    override fun onDrawFrame(g:GL10){}
}

Answer 1

u_LightPos的类型是浮点（vec3）：

uniform vec3 u_LightPos; 

您必须使用glUniform3f而不是glUniform3f来设置浮点统一变量的值：

glUniform3i

glUniform3i(uLightPos,-1,-10,-1)

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我建议验证glUniform3f(uLightPos,-1f,-10f,-1f) （参数glGetShaderiv）是否成功编译了着色器。可以通过glGetShaderiv

检索编译错误消息

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我建议添加环境光组件（出于调试原因）例如：

GL_COMPILE_STATUS

如果您可以通过环境光“看到”几何，则可能存在一些问题：

1. 光源位于几何图形的背面，因此背面被照亮，但正面不被照亮。这导致从视图的角度来看几乎只有黑色，不发光的一面可见。

2. 光源到几何的距离“太大”。 glGetShaderInfoLog变为非常大的值，因此glGetShaderInfoLog很小，所有几何图形几乎都是黑色的。

3. 光源在几何的封闭空间中。

4. 所有法线向量都指向远离摄像机的方向。这可能会导致v_Color = a_Color*(diffuse + 0.5); 小于0.0。