【移动应用开发技术】怎么在Android中利用OpenGLES绘制一个天空盒

【移动应用开发技术】怎么在Android中利用OpenGLES绘制一个天空盒

怎么在Android中利用OpenGLES绘制一个天空盒？相信很多没有经验的人对此束手无策，为此本文总结了问题出现的原因和解决方法，通过这篇文章希望你能解决这个问题。第一步SkyBoxView继承了GLSurfaceView，为什么要继承GLSurfaceView，因为在使用OpenGLES需要建立一个窗口和一个上下文，GLSurfaceView帮我们做了这些工作。下面是SkyBoxView的主要代码：class

SkyBoxView(context:

Context,

attributeSet:

AttributeSet?)

:

GLSurfaceView(context,

attributeSet)

{

private

lateinit

var

skyBoxRender:

SkyBoxRender

private

var

lastX=0F

private

var

lastY=0F

private

var

yaw=0f

private

var

pitch=0f

private

var

screenWidth=0

private

var

screenHeight=0

private

var

horSensity=0.03f

private

var

verSensity=0.03f

constructor(context:

Context)

:

this(context,

null)

init

{

//

initSensor()

initSensity()

initConfig()

}

private

fun

initSensity()

{

screenWidth=resources.displayMetrics.widthPixels

screenHeight=resources.displayMetrics.heightPixels

horSensity=

360.0f/screenWidth

verSensity=180.0f/screenHeight

}

private

fun

rotate(pitch:Float,yaw:Float)

{

queueEvent

{

skyBoxRender.rotate(pitch,yaw)

}

}

private

fun

initConfig()

{

setEGLContextClientVersion(3)

skyBoxRender=SkyBoxRender(context)

setRenderer(skyBoxRender)

renderMode

=

GLSurfaceView.RENDERMODE_CONTINUOUSLY

}

override

fun

onTouchEvent(event:

MotionEvent?):

Boolean

{

when(event?.action)

{

MotionEvent.ACTION_DOWN->

{

lastX=event.x

lastY=event.y

return

true

}

MotionEvent.ACTION_MOVE->

{

val

offsetX=event.x-lastX

val

offsetY=lastY-event.y

yaw+=offsetX*horSensity

pitch+=offsetY*verSensity

lastX=event.x

lastY=event.y

skyBoxRender.rotate(pitch,yaw)

}

}

return

true

}

}在initConfig方法里，设置了render为SkyBoxRender，真正的绘制是在这里进行的。在initSensity方法里设置了旋转精度，horSensity和verSensity,水平和数值旋转时的精度，就像你玩fps游戏设置的鼠标灵敏度一样。在onTouchEvent则根据手指滑动的距离设置俯仰角pitch和偏移脚yaw，调用skyBoxRender进行相机的旋转。另外如果你看github可能发现我注释掉了很多代码，那是用传感器旋转的尝试，但是觉得麻烦，也没继续做，有兴趣的读者可以自己搞一下。第二步SkyboxRender的主要工作就是加载贴在正方体表面的6个图片纹理,从文件读取着色器语言，而真正创建openglesprogram和绘制是用C++代码来写的，所以主要看一下这里。#include

<jni.h>

#include

<string>

#include

<GLUtils/GLUtils.h>

#include

<glm/glm.hpp>

#include

<glm/gtc/type_ptr.hpp>

#include

<glm/gtc/matrix_transform.hpp>

extern

"C"

{

JNIEXPORT

jint

JNICALL

Java_com_skateboard_skybox_SkyBoxRender_genProgram(JNIEnv

*env,

jobject

thiz,

jstring

vertexPath,

jstring

fragmentPath)

{

//load

program

const

char

*cVertexPath

=

env->GetStringUTFChars(vertexPath,

nullptr);

const

char

*cFragmentPath

=

env->GetStringUTFChars(fragmentPath,

nullptr);

int

program

=

glutils::loadProgram(cVertexPath,

cFragmentPath);

return

program;

}

JNIEXPORT

jint

JNICALL

Java_com_skateboard_skybox_SkyBoxRender_preparePos(JNIEnv

*env,

jobject

thiz,

jfloatArray

pos)

{

//gen

vao

vbo

unsigned

int

VAO,

VBO;

glGenVertexArrays(1,

&VAO);

glBindVertexArray(VAO);

glGenBuffers(1,

&VBO);

glBindBuffer(GL_ARRAY_BUFFER,

VBO);

int

posSize

=

env->GetArrayLength(pos);

float*

p=env->GetFloatArrayElements(pos,

nullptr);

glBufferData(GL_ARRAY_BUFFER,

posSize*

sizeof(float),

p,

GL_STATIC_DRAW);

glEnableVertexAttribArray(0);

glVertexAttribPointer(0,

3,

GL_FLOAT,

GL_FALSE,

3

*

sizeof(float),

0);

glBindVertexArray(0);

return

VAO;

}

JNIEXPORT

jint

JNICALL

Java_com_skateboard_skybox_SkyBoxRender_prepareTexture(JNIEnv

*env,

jobject

thiz)

{

//gen

texture

unsigned

int

TEXTURE;

glGenTextures(1,

&TEXTURE);

glBindTexture(GL_TEXTURE_CUBE_MAP,

TEXTURE);

glTexParameteri(GL_TEXTURE_CUBE_MAP,

GL_TEXTURE_MAG_FILTER,

GL_LINEAR);

glTexParameteri(GL_TEXTURE_CUBE_MAP,

GL_TEXTURE_MIN_FILTER,

GL_LINEAR);

glTexParameteri(GL_TEXTURE_CUBE_MAP,

GL_TEXTURE_WRAP_S,

GL_CLAMP_TO_EDGE);

glTexParameteri(GL_TEXTURE_CUBE_MAP,

GL_TEXTURE_WRAP_T,

GL_CLAMP_TO_EDGE);

glTexParameteri(GL_TEXTURE_CUBE_MAP,

GL_TEXTURE_WRAP_R,

GL_CLAMP_TO_EDGE);

return

1;

}

glm::vec3

cameraPos

=

glm::vec3(0.0f,

0.0f,

0.0f);

glm::vec3

cameraFront

=

glm::vec3(0.0f,

0.0f,

-1.0f);

JNIEXPORT

void

JNICALL

Java_com_skateboard_skybox_SkyBoxRender_draw(JNIEnv

*env,

jobject

thiz,

jint

program,

jint

VAO,

jint

texture,jfloat

width,jfloat

height)

{

glClear(GL_COLOR_BUFFER_BIT

|

GL_DEPTH_BUFFER_BIT);

glClearColor(0.0,

1.0,

0.0,

1.0);

glUseProgram(program);

glEnable(GL_DEPTH_TEST);

glm::mat4

viewMatrix

=

glm::mat4(1.0f);

glm::mat4

projectionMatrix

=

glm::mat4(1.0f);

glm::vec3

v

=

glm::vec3(cameraFront.x

-

cameraPos.x,

cameraFront.y

-

cameraPos.y,

cameraFront.z

-

cameraPos.z);

viewMatrix

=

glm::lookAt(cameraPos,

v,

glm::vec3(0.0f,

1.0f,

0.0f));

projectionMatrix

=

glm::perspective(glm::radians(45.0f),

width

/

height,

0.1f,

100.0f);

int

viewMatrixLocation

=

glGetUniformLocation(program,

"view");

int

projectMatrixLocation

=

glGetUniformLocation(program,

"projection");

glUniformMatrix4fv(viewMatrixLocation,

1,

GL_FALSE,

&viewMatrix[0][0]);

glUniformMatrix4fv(projectMatrixLocation,

1,

GL_FALSE,

&projectionMatrix[0][0]);

glBindVertexArray(VAO);

glBindTexture(GL_TEXTURE_CUBE_MAP,

texture);

glDrawArrays(GL_TRIANGLES,

0,

36);

}JNIEXPORT

void

JNICALL

Java_com_skateboard_skybox_SkyBoxRender_rotate(JNIEnv

*env,

jobject

thiz,jfloat

pitch,jfloat

yaw)

{

if(pitch>89)

{

pitch=89.0;

}

if(pitch<-89)

{

pitch=-89.0;

}

cameraFront.x=glm::cos(glm::radians(pitch))*glm::cos(glm::radians(yaw));

cameraFront.y=glm::sin(glm::radians(pitch));

cameraFro