OpenGL系列之六：绘制立方体
2022-11-27 本文已影响0人
itfitness
目录
相关文章
OpenGL系列之一：OpenGL第一个程序
OpenGL系列之二：绘制三角形
OpenGL系列之三：三角形顶点增加颜色
OpenGL系列之四：绘制四边形
OpenGL系列之五：绘制点和线
实现效果
实现步骤
1.下载glm
https://github.com/g-truc/glm
下载完如下：
2.引入glm
在项目cpp文件夹下新建3rdparty\libglm\include，然后将上面下载的glm文件夹复制到3rdparty\libglm\include文件夹下。
3.CMakeLists.txt配置
CMakeLists.txt增加如下配置：
#增加glm
SET(GLM_DIR ${CMAKE_CURRENT_SOURCE_DIR}/src/main/cpp/3rdparty/libglm)
INCLUDE_DIRECTORIES(${GLM_DIR}/include)
完整如下：
cmake_minimum_required(VERSION 3.10)
#增加glm
SET(GLM_DIR ${CMAKE_CURRENT_SOURCE_DIR}/src/main/cpp/3rdparty/libglm)
INCLUDE_DIRECTORIES(${GLM_DIR}/include)
add_library(CCOpenGLRender SHARED src/main/cpp/CCOpenGLRender.cpp)
target_link_libraries(
CCOpenGLRender
-lGLESv1_CM #OpenGL V1
-lGLESv2 #OpenGL V2
log
)
4.编写代码
这里是以之前的第五个程序（OpenGL系列之五：绘制点和线
）为基础，主要就是修改了CCOpenGLRender.cpp，完整CCOpenGLRender.cpp代码如下（附注释）：
#include <jni.h>
#include <GLES/gl.h>
#include <GLES2/gl2.h>
#include "CCGLPrimitivesDef.h"
//引入glm头文件
#include <glm/vec3.hpp>
#include <glm/vec4.hpp>
#include <glm/mat4x4.hpp>
#include <glm/glm.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <glm/ext/matrix_transform.hpp>
#include <glm/ext/matrix_clip_space.hpp>
//立方体旋转角度
float m_angle =0.0f;
extern "C"
JNIEXPORT void JNICALL
Java_com_itfitness_opengldemo_GLRender_ndkInitGL(JNIEnv *env, jobject thiz) {
//清空颜色
glClearColor(0.0,0,0,1.0);
//清空深度缓存
glClearDepthf(1.0);
//开启深度测试
glEnable(GL_DEPTH_TEST);
//什么情况下使用深度测试
glDepthFunc(GL_LEQUAL);
}
extern "C"
JNIEXPORT void JNICALL
Java_com_itfitness_opengldemo_GLRender_ndkPaintGL(JNIEnv *env, jobject thiz) {
//清空颜色缓冲区或深度缓冲区
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
//加载模型视图矩阵
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glCullFace(GL_BACK);
//定义立方体顶点
CCFloat7 cubeVert[] = {
{-0.5f, -0.5f, -0.5f, 1.0,0.0,0.0,1.0},
{0.5f, -0.5f, -0.5f, 1.0,0.0,0.0,1.0},
{0.5f, 0.5f, -0.5f, 1.0,0.0,0.0,1.0},
{0.5f, 0.5f, -0.5f, 1.0,0.0,0.0,1.0},
{-0.5f, 0.5f, -0.5f, 1.0,0.0,0.0,1.0},
{-0.5f, -0.5f, -0.5f, 1.0,0.0,0.0,1.0},
{-0.5f, -0.5f, 0.5f, 0.0,1.0,0.0,1.0},
{0.5f, -0.5f, 0.5f, 0.0,1.0,0.0,1.0},
{0.5f, 0.5f, 0.5f, 0.0,1.0,0.0,1.0},
{0.5f, 0.5f, 0.5f, 0.0,1.0,0.0,1.0},
{-0.5f, 0.5f, 0.5f, 0.0,1.0,0.0,1.0},
{-0.5f, -0.5f, 0.5f, 0.0,1.0,0.0,1.0},
{-0.5f, 0.5f, 0.5f, 0.0,0.0,1.0,1.0},
{-0.5f, 0.5f, -0.5f, 0.0,0.0,1.0,1.0},
{-0.5f, -0.5f, -0.5f, 0.0,0.0,1.0,1.0},
{-0.5f, -0.5f, -0.5f, 0.0,0.0,1.0,1.0},
{-0.5f, -0.5f, 0.5f, 0.0,0.0,1.0,1.0},
{-0.5f, 0.5f, 0.5f, 0.0,0.0,1.0,1.0},
{0.5f, 0.5f, 0.5f, 0.0,0.0,1.0,1.0},
{0.5f, 0.5f, -0.5f, 0.0,0.0,1.0,1.0},
{0.5f, -0.5f, -0.5f, 0.0,0.0,1.0,1.0},
{0.5f, -0.5f, -0.5f, 0.0,0.0,1.0,1.0},
{0.5f, -0.5f, 0.5f, 0.0,0.0,1.0,1.0},
{0.5f, 0.5f, 0.5f, 0.0,0.0,1.0,1.0},
{-0.5f, -0.5f, -0.5f, 0.0,1.0,0.0,1.0},
{0.5f, -0.5f, -0.5f, 0.0,1.0,0.0,1.0},
{0.5f, -0.5f, 0.5f, 0.0,1.0,0.0,1.0},
{0.5f, -0.5f, 0.5f, 0.0,1.0,0.0,1.0},
{-0.5f, -0.5f, 0.5f, 0.0,1.0,0.0,1.0},
{-0.5f, -0.5f, -0.5f, 0.0,1.0,0.0,1.0},
{-0.5f, 0.5f, -0.5f, 1.0,0.0,0.0,1.0},
{0.5f, 0.5f, -0.5f, 1.0,0.0,0.0,1.0},
{0.5f, 0.5f, 0.5f, 1.0,0.0,0.0,1.0},
{0.5f, 0.5f, 0.5f, 1.0,0.0,0.0,1.0},
{-0.5f, 0.5f, 0.5f, 1.0,0.0,0.0,1.0},
{-0.5f, 0.5f, -0.5f, 1.0,0.0,0.0,1.0}
};
//启动一组顶点坐标
glEnableClientState(GL_VERTEX_ARRAY);
//启动颜色
glEnableClientState(GL_COLOR_ARRAY);
// 指定绘制的定点数组
// 第一个参数：绘制几个点（这里其实就是CCFloat7中的前三个点x,y,z）
// 第二个参数：类型为float
// 第三个参数：第一个点到第二个点之间的步长（也就是结构体的长度）
// 第四个参数：绘制数据的地址
glVertexPointer(3,GL_FLOAT,sizeof(CCFloat7),cubeVert);
glColorPointer(4,GL_FLOAT,sizeof(CCFloat7),&cubeVert[0].r);
//每次绘制角度都增加
m_angle += 0.05f;
glm::mat4x4 cubeMat;
//平移矩阵
glm::mat4x4 cubeTransMat = glm::translate(glm::mat4(1.0f), glm::vec3(0.0f, 0.0f, -0.5));
//旋转矩阵
glm::mat4x4 cubeRotMat = glm::rotate(glm::mat4(1.0f),m_angle,glm::vec3(0.5f, 0.5f, 1.0) );
//缩放矩阵
glm::mat4x4 cubeScaleMat = glm::scale(glm::mat4(1.0f),glm::vec3(0.5f, 0.5f, 0.5) );
cubeMat = cubeTransMat * cubeRotMat * cubeScaleMat;
//加载矩阵
glLoadMatrixf(glm::value_ptr(cubeMat));
// 绘制三角形（立方体由三角形组成）
glDrawArrays(GL_TRIANGLES,0,36);
//关闭一组顶点坐标
glDisableClientState(GL_VERTEX_ARRAY);
//关闭颜色
glDisableClientState(GL_COLOR_ARRAY);
}
extern "C"
JNIEXPORT void JNICALL
Java_com_itfitness_opengldemo_GLRender_ndkResizeGL(JNIEnv *env, jobject thiz, jint width,
jint height) {
//设置窗口大小
glViewport(0,0,width,height);
//投影矩阵
glMatrixMode(GL_PROJECTION);
//重置投影矩阵
glLoadIdentity();
//摄像机
glOrthof(-1,1,-1,1,0,1000);
//添加模型视图矩阵
glMatrixMode(GL_MODELVIEW);
//重置当前指定的矩阵为单位矩阵
glLoadIdentity();
}
