GLES20.glUniform4fv和fragshader

问题描述

好的，所以我试图在一个对象中循环并使用多种颜色，但似乎无法弄清楚并诚实地将头发撕开，但是此代码来自Android指南，我一直在玩现在绕过它一分钟，并尝试了许多不同的方法，但总是最后回到问题所在：“是片段着色器，还是我只是在使用函数GLES20.glUniform4fv（colorHandle，2，color，0）错误？如果不能接受颜色的数组参数，为什么要有一个'count'值和一个数组参数？”

class Triangle {
    private var mProgram: Int
    private var vPMatrixHandle: Int = 0
    private var positionHandle: Int = 0
    private var mColorHandle: Int = 0
    private val fragmentShaderCode: String =
        "precision mediump float;\n" +
        "uniform vec4 vColor[];\n" +
        "void main() {\n" +
            "\tgl_FragColor = vColor;\n" +
        "}"
    private val vertexShaderCode: String =
        "uniform mat4 uMVPMatrix;\n" +
        "attribute vec4 vPosition;\n" +
        "void main() {\n" +
            "\tgl_Position = uMVPMatrix * vPosition;\n" +
        "}"

    private val COORDS_PER_VERTEX: Int = 3
    private var triangleCoords: FloatArray = floatArrayOf(
        -0.5f,-0.5f,0.5f,0.5f
    )
    private val color: FloatArray = floatArrayOf(
        0.63671875f,0.76953125f,0.22265625f,1.0f,0.63671875f,0.22953125f,0.78265625f,1.0f
    )
    private val indiceCoords: ByteArray = byteArrayOf(
        0,4,5,1,6,2,7,3,2
    )

    private val vertexCount: Int = triangleCoords.size / COORDS_PER_VERTEX
    private val vertexStride: Int = COORDS_PER_VERTEX * 4

    private var vertexBuffer: FloatBuffer =
        ByteBuffer.allocateDirect(triangleCoords.size * 4).run {
            order(ByteOrder.nativeOrder())
            asFloatBuffer().apply {
                put(triangleCoords)
                position(0)
            }
        }

    private var indiceBuffer: ByteBuffer =
        ByteBuffer.allocateDirect(indiceCoords.size * 4).run {
            order(ByteOrder.nativeOrder()).apply {
                put(indiceCoords)
                position(0)
            }
        }

    init {
        val vertexShader: Int = loadShader(GLES20.GL_VERTEX_SHADER,vertexShaderCode)
        val fragmentShader: Int = loadShader(GLES20.GL_FRAGMENT_SHADER,fragmentShaderCode)
        mProgram = GLES20.glCreateProgram().also {
            GLES20.glAttachShader(it,vertexShader)
            GLES20.glAttachShader(it,fragmentShader)
            GLES20.glLinkProgram(it)
        }
    }

    fun loadShader(type: Int,shaderCode: String): Int {
        return GLES20.glCreateShader(type).also { shader ->
            GLES20.glShaderSource(shader,shaderCode)
            GLES20.glCompileShader(shader)
        }
    }

    fun draw(mvpMatrix: FloatArray) {
        GLES20.glUseProgram(mProgram)
        positionHandle = GLES20.glGetAttribLocation(mProgram,"vPosition").also {
            GLES20.glEnableVertexAttribArray(it)
            GLES20.glVertexAttribPointer(
                it,COORDS_PER_VERTEX,GLES20.GL_FLOAT,false,vertexStride,vertexBuffer
            )
            mColorHandle = GLES20.glGetUniformLocation(mProgram,"vColor").also { colorHandle ->
                GLES20.glUniform4fv(colorHandle,color,0)
            }
            vPMatrixHandle = GLES20.glGetUniformLocation(mProgram,"uMVPMatrix")
            GLES20.glUniformMatrix4fv(vPMatrixHandle,mvpMatrix,0)
            GLES20.glDrawElements(GL10.GL_TRIANGLES,36,GL10.GL_UNSIGNED_BYTE,indiceBuffer)
            GLES20.glDisableVertexAttribArray(it)
        }
    }
}

解决方法

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