OpenGL ES：如何將 VAO 與 glVertexAttribPointer 一起使用？

Question

我正在嘗試使用 VAO 更新以下代碼：

fun onSurfaceCreated() {
    // ...

    // Coordinates Handle
    this.meshCoordinatesHandle = GLES31.glGetAttribLocation(program, "mesh_coordinates")
    GLES31.glEnableVertexAttribArray(this.meshCoordinatesHandle)

    // Color Handle
    this.colorHandle = GLES31.glGetUniformLocation(program, "color")
    GLES31.glEnableVertexAttribArray(this.colorHandle)
}

fun onDrawFrame() {
    // ...

    // Mesh A
    GLES31.glVertexAttribPointer(this.meshCoordinatesHandle, 3, GLES31.GL_FLOAT, false, 3 * 4, this.meshACoordinatesBuffer)
    GLES31.glUniform4fv(this.colorHandle, 1, this.meshAColor, 0)
    GLES31.glDrawElements(GLES31.GL_LINES, this.meshALinesBuffer.capacity(), GLES31.GL_UNSIGNED_SHORT, this.meshALinesBuffer)

    // Mesh B
    GLES31.glVertexAttribPointer(this.meshCoordinatesHandle, 3, GLES31.GL_FLOAT, false, 3 * 4, this.meshBCoordinatesBuffer)
    GLES31.glUniform4fv(this.colorHandle, 1, this.meshBColor, 0)
    GLES31.glDrawElements(GLES31.GL_LINES, this.meshBLinesBuffer.capacity(), GLES31.GL_UNSIGNED_SHORT, this.meshBLinesBuffer)
}

我走了這么遠，但我被困在這里：

fun onSurfaceCreated() {
    // ...

    GLES31.glGenVertexArrays(2, vaos, 0)

    // VAO A
    GLES31.glBindVertexArray(vaos[0])

    GLES31.glGetAttribLocation(program, "mesh_coordinates").also {
    GLES31.glEnableVertexAttribArray(it)
    GLES31.glVertexAttribPointer(it, 3, GLES31.GL_FLOAT, false, 3 * 4, this.meshACoordinatesBuffer)
    }

    GLES31.glGetUniformLocation(program, "color").also {
    GLES31.glEnableVertexAttribArray(it)
    GLES31.glUniform4fv(it, 1, this.meshAColor, 0)
    }

    // VAO B
    GLES31.glBindVertexArray(vaos[1])

    GLES31.glGetAttribLocation(program, "mesh_coordinates").also {
    GLES31.glEnableVertexAttribArray(it)
    GLES31.glVertexAttribPointer(it, 3, GLES31.GL_FLOAT, false, 3 * 4, this.meshBCoordinatesBuffer)
    }

    GLES31.glGetUniformLocation(program, "color").also {
    GLES31.glEnableVertexAttribArray(it)
    GLES31.glUniform4fv(it, 1, this.meshBColor, 0)
    }
}

fun onDrawFrame() {
    // ...

    // Mesh A
    GLES31.glBindVertexArray(vaos[0])
    GLES31.glDrawElements(GLES31.GL_LINES, this.meshALinesBuffer.capacity(), GLES31.GL_UNSIGNED_SHORT, this.meshALinesBuffer)

    // Mesh B
    GLES31.glBindVertexArray(vaos[1])
    GLES31.glDrawElements(GLES31.GL_LINES, this.meshBLinesBuffer.capacity(), GLES31.GL_UNSIGNED_SHORT, this.meshBLinesBuffer)
}

知道問題可能來自哪里嗎？ 我必須用glBindBuffer和glBufferData替換glVertexAttribPointer嗎？

Answer 1

制服存儲在當前安裝程序的默認制服塊中。 制服不是VAO的狀態。 制服是程序的一部分，但不是屬性的一部分。 如果要組織制服，可以使用Uniform Buffer Object或Shader Storage Buffer Objects 。

在繪制網格之前設置均勻：

fun onSurfaceCreated() {
    // [...]

    GLES31.glGenVertexArrays(2, vaos, 0)

    // VAO A
    GLES31.glBindVertexArray(vaos[0])
    GLES31.glGetAttribLocation(program, "mesh_coordinates").also {
       GLES31.glEnableVertexAttribArray(it)
       GLES31.glVertexAttribPointer(it, 3, GLES31.GL_FLOAT, false, 3 * 4, this.meshACoordinatesBuffer)
    }

    // VAO B
    GLES31.glBindVertexArray(vaos[1])
    GLES31.glGetAttribLocation(program, "mesh_coordinates").also {
       GLES31.glEnableVertexAttribArray(it)
       GLES31.glVertexAttribPointer(it, 3, GLES31.GL_FLOAT, false, 3 * 4, this.meshBCoordinatesBuffer)
    }
}

fun onDrawFrame() {
    // [...]

    // Mesh A
    GLES31.glGetUniformLocation(program, "color").also {
       GLES31.glUniform4fv(it, 1, this.meshAColor, 0)
    }
    GLES31.glBindVertexArray(vaos[0])
    GLES31.glDrawElements(GLES31.GL_LINES, this.meshALinesBuffer.capacity(), GLES31.GL_UNSIGNED_SHORT, this.meshALinesBuffer)

    // Mesh B
    GLES31.glGetUniformLocation(program, "color").also {
       GLES31.glUniform4fv(it, 1, this.meshBColor, 0)
    }
    GLES31.glBindVertexArray(vaos[1])
    GLES31.glDrawElements(GLES31.GL_LINES, this.meshBLinesBuffer.capacity(), GLES31.GL_UNSIGNED_SHORT, this.meshBLinesBuffer)
}