OpenGL ES Android 2D视图似乎被缩小到无穷大

Question

我有一个Kotlin沙箱应用程序，可以在Android Studio中试用OpenGL ES。我按照教程的要求，成功地创建了具有适当纵横比的三角形、直线和点。我正在使用OpenGLES2为Android的书，并转换到Kotlin。此处提供源代码。

我偏离了这本书，试图创建一个用于平移和缩放的2D可转换视图(目前我对3D功能不太感兴趣(，所以我参考了Android开发人员的文档，在代码混乱的地方，我创建了一个错误。尽管缩放并将点移动到不同的位置，但显示的是中心的单个点。点渲染是因为着色器是10px，我怀疑三角形在那里，但太小了。也许在管道中的某个地方正在应用0的刻度？我尝试手动缩放正交视图，但在非常极端的数字下没有效果。我将这些点从原点移开，所有这些点在隔离时仍显示在原点。所以我认为0缩放可能正在发生。

我的预期结果是，当setLookAtM和点顶点定义为1.0f和-1.0f时，可以看到点出现在1.0f和1.0f之间。

渲染器：

package com.e
import android.content.Context
import android.opengl.GLES20.*
import android.opengl.GLSurfaceView.Renderer
import android.opengl.Matrix
import android.opengl.Matrix.*
import com.e.mysandboxapplication.R
import util.LoggerConfig
import util.ShaderHelper
import util.TextResourceReaderService
import java.nio.ByteBuffer
import java.nio.ByteOrder
import java.nio.FloatBuffer
import javax.microedition.khronos.egl.EGLConfig
import javax.microedition.khronos.opengles.GL10

class Open2DMapGLRenderer (
private var context: Context
) : Renderer  {
private val U_Matrix = "u_Matrix"
private var projectionMatrix = FloatArray(16)
private var viewMatrix = FloatArray(16)
private val vPMatrix = FloatArray(16)
private var vPMatrixHandle = 0
private var uMatrixLocation = 0
private val BYTES_PER_FLOAT = 4
private lateinit var vertexData : FloatBuffer
private var program = 0
private val u_Color = "u_Color"
private var uColorLocation = 0
private var a_Position = "a_Position"
private var aPositionLocation = 0
private var POSITION_COMPONENT_COUNT = 2
init{
val vertices = PopulateVertices()
vertexData = ByteBuffer.allocateDirect(vertices.count() * BYTES_PER_FLOAT)
.order(ByteOrder.nativeOrder())
.asFloatBuffer()
vertexData.put(vertices)
}
private fun PopulateVertices(): FloatArray {
val vertices = floatArrayOf(
// Triangle 1
-0.5f, -0.5f,
0.5f, 0.5f,
-0.5f, 0.5f,
// Triangle 2
-0.5f, -0.5f,
0.5f, -0.5f,
0.5f, 0.5f,
// Line 1
-0.5f, 0f,
0.5f, 0f,
// Points
0.5f, 0.5f,
-0.5f, -0.5f,
0.0f, 0.0f
)
return vertices
}
override fun onDrawFrame(gl: GL10?) {
glClear(GL_COLOR_BUFFER_BIT)
setLookAtM(viewMatrix, 0, 0f, 0f, 1.0f, 0f, 0f, 0f, 0f, 1.0f, 0f)
multiplyMM(vPMatrix, 0, projectionMatrix, 0, viewMatrix, 0)
vPMatrixHandle = glGetUniformLocation(program, "uMVPMatrix")
glUniformMatrix4fv(vPMatrixHandle, 1, false, vPMatrix, 0)
DrawTriangles()
DrawPoints()
DrawLines()
}
private fun DrawPoints() {
glUniform4f(uColorLocation, 1.0f, 1.0f, 1.0f, 1.0f)
glDrawArrays(GL_POINTS, 8, 3)
}
private fun DrawLines() {
glUniform4f(uColorLocation, 0f, 0f, 1.0f, 1.0f)
glDrawArrays(GL_LINES, 6, 2)
}
private fun DrawTriangles() {
glUniform4f(uColorLocation, 1.0f, 1.0f, 1.0f, 1.0f)
glDrawArrays(GL_TRIANGLES, 0, 6)
}
override fun onSurfaceChanged(gl: GL10?, width: Int, height: Int) {
var isPortrait = width > height
glViewport(0, 0, width, height)
var scale = 1.0f // added this for diagnostics. No apparent effect.
var aspectRatio = if ( isPortrait ) { width / height.toFloat() } else { height / width.toFloat() }
if (isPortrait) {
// Portrait
orthoM(projectionMatrix, 0, -aspectRatio * scale , aspectRatio * scale, -scale, scale, -2.0f, 2.0f)
}else{
// Landscape
orthoM(projectionMatrix, 0 , -scale, scale, -aspectRatio * scale , aspectRatio * scale, -2.0f, 2.0f)
}
}
override fun onSurfaceCreated(gl: GL10?, config: EGLConfig?) {
glClearColor(0.75f,0.75f,0.75f,1.0f)
val vertexShaderSource : String = TextResourceReaderService()
.readTextFileFromResource(context, R.raw.simple_vertex_shader)
val fragmentShaderSource : String = TextResourceReaderService()
.readTextFileFromResource(context, R.raw.simple_fragment_shader)
val vertexShader : Int = ShaderHelper().compileVertexShader(vertexShaderSource)
val fragmentShader : Int = ShaderHelper().compileFragmentShader(fragmentShaderSource)
program = ShaderHelper().linkProgram(vertexShader, fragmentShader)
if(LoggerConfig.ON) {
ShaderHelper().validateProgram(program)
}
glUseProgram(program)
uColorLocation = glGetUniformLocation(program, u_Color)
aPositionLocation = glGetAttribLocation(program, a_Position)
vertexData.position(0)
glVertexAttribPointer(aPositionLocation, POSITION_COMPONENT_COUNT, GL_FLOAT, false, 0, vertexData)
glEnableVertexAttribArray(aPositionLocation)
uMatrixLocation = glGetUniformLocation(program, U_Matrix)
}
}

ShaderHelper实用程序类：

import android.opengl.GLES20.*
import android.util.Log
public class ShaderHelper{
private val TAG : String = "ShaderHelper"
public fun compileVertexShader (shaderCode : String): Int{
return compileShader(GL_VERTEX_SHADER, shaderCode)
}
public fun compileFragmentShader (shaderCode : String): Int{
return compileShader(GL_FRAGMENT_SHADER, shaderCode)
}
private fun compileShader(type: Int , shaderCode: String) : Int{
val shaderObjectId : Int = glCreateShader(type)
if(shaderObjectId == 0){
if (LoggerConfig.ON){
Log.w(TAG, "Could not create new Shader.")
}
return 0
}
glShaderSource(shaderObjectId, shaderCode)
glCompileShader(shaderObjectId)
val compileStatus : IntArray = IntArray(1)
glGetShaderiv(shaderObjectId, GL_COMPILE_STATUS, compileStatus, 0 )
if(LoggerConfig.ON){
Log.v(TAG, "Results of compiling source: " + "n" + shaderCode + "n"
+ glGetShaderInfoLog(shaderObjectId))
}
if(compileStatus[0] == 0){
glDeleteShader(shaderObjectId)
Log.v(TAG, "Compilation of shader failed.")
return 0
}
return shaderObjectId
}
public fun linkProgram (vertexShaderId : Int, fragmentShaderId : Int) : Int {
val programObjectId : Int = glCreateProgram()
if(programObjectId == 0) {
if (LoggerConfig.ON) {
Log.v(TAG, "Could not create GL Program.")
}
return 0
}
glAttachShader(programObjectId, vertexShaderId)
glAttachShader(programObjectId, fragmentShaderId)
glLinkProgram(programObjectId)
val linkStatus : IntArray = IntArray(1)
glGetProgramiv(programObjectId, GL_LINK_STATUS, linkStatus, 0)
if (LoggerConfig.ON) {
// Print the program info log to the Android log output.
Log.v(TAG, "Results of linking program:n"
+ glGetProgramInfoLog(programObjectId));
}
if(linkStatus[0] == 0) {
glDeleteProgram(programObjectId)
if(LoggerConfig.ON){
Log.v(TAG, "Linking of program failed.n")
}
return 0
}
return programObjectId
}
public fun validateProgram(programObjectId : Int) : Boolean{
glValidateProgram(programObjectId)
val validateStatus = IntArray(1)
glGetProgramiv(programObjectId, GL_VALIDATE_STATUS, validateStatus, 0);
Log.v(TAG, "Results of validating program: " + validateStatus[0]
+ "nLog:" + glGetProgramInfoLog(programObjectId));
return validateStatus[0] != 0;  
}
}

顶点着色器：

uniform mat4 uMVPMatrix;
attribute vec4 v_Position;
void main()
{
gl_Position = uMVPMatrix * v_Position;
gl_PointSize = 10.0;
}

片段着色器：

precision mediump float;
uniform vec4 u_Color;
void main()
{
gl_FragColor = u_Color;
}

Answer 1

问题是顶点着色器位置的变量包含拼写错误。

private var a_Position = "a_Position"

与着色器不匹配：

attribute vec4 v_Position;

导致包含在0,0,0处的所有内容。