QT+OpenGL七之使用EBO

EBO（顶点索引缓冲区）
重新写一个shader程序：
shaderMode.vs

#version 430 
uniform mat4 mv_matrix;
uniform mat4 proj_matrix;
in vec3 vPosition;
void main(void)
{
gl_Position=proj_matrix*mv_matrix*vec4(vPosition,1.0);
}

shaderModel.fs

#version 430 
out vec4 color;
uniform mat4 mv_matrix;
uniform mat4 proj_matrix;


void main(void) 
{
color =vec4(1.0,0.0,0.0,1.0) ;
}

myTest.h

#pragma once
#include "Camera.h"
class myTest : protected QOpenGLFunctions_4_3_Core
{
public:
    myTest();
    ~myTest();
    void init(QOpenGLShaderProgram* shaderProgram);
    void draw(Camera camera);
private:
    GLuint vPosition;
    float cubeLocX=4.0, cubeLocY=0.0, cubeLocZ=-8.0;
    GLuint mvLoc;
    QMatrix4x4 mvMat;
    QOpenGLVertexArrayObject vao;
    QOpenGLBuffer vbo, ebo;
    QOpenGLShaderProgram* shaderProgram;
};

myTest.cpp

#include "stdafx.h"
#include "myTest.h"
myTest::myTest():ebo(QOpenGLBuffer::IndexBuffer){
}
myTest::~myTest() {
    vbo.destroy();
}
void myTest::init(QOpenGLShaderProgram* shaderProgram) {
    initializeOpenGLFunctions();
    this->shaderProgram = shaderProgram;
    shaderProgram->bind();
    GLfloat vertexPositions[] = {
     -0.5,-0.5,-0.5,
    -0.5,-0.5,0.5,
    0.5,-0.5,0.5,
    0.5,-0.5,-0.5,
    -0.5,0.5,-0.5,
    -0.5,0.5,0.5,
    0.5,0.5,0.5,
    0.5,0.5,-0.5,
    };
    GLuint triIndexs[] = { 0,2,1,
                     0,2,3,
                     2,5,1,
                     2,5,6,
                     2,7,3,
                     2,7,6,
                     0,5,1,
                     0,5,4,
                     4,6,5,
                     4,6,7,
                     0,7,4,
                     0,7,3 };
    vao.create();
    vbo.create();
    ebo.create();
    vao.bind();
    vbo.bind();
    vbo.setUsagePattern(QOpenGLBuffer::StaticDraw);
    vbo.allocate(vertexPositions, sizeof(vertexPositions));
    vPosition = shaderProgram->attributeLocation("vPosition");
    shaderProgram->setAttributeBuffer(vPosition, GL_FLOAT, 0, 3, sizeof(float) * 3);
    glEnableVertexAttribArray(vPosition);
    ebo.bind();
    ebo.setUsagePattern(QOpenGLBuffer::StaticDraw);
    ebo.allocate(triIndexs, sizeof(triIndexs));
    vao.release();
    shaderProgram->release();
}

void myTest::draw(Camera camera) {
    shaderProgram->bind();
    mvLoc = shaderProgram->uniformLocation("mv_matrix");
    //构建视图矩阵
    QMatrix4x4 m;
    m.translate(cubeLocX, cubeLocY, cubeLocZ);
    QMatrix4x4 v;
    v.lookAt(QVector3D(camera.location.x, camera.location.y, camera.location.z),
        QVector3D(camera.viewPoint.x, camera.viewPoint.y, camera.viewPoint.z),
        QVector3D(camera.worldY.x, camera.worldY.y, camera.worldY.z));
    mvMat = v * m;
    shaderProgram->setUniformValue(mvLoc, mvMat);
    vao.bind();
    //glDrawArrays(GL_TRIANGLES, 0, 36);
    glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, 0);
    vao.release();
    shaderProgram->release();
}

效果图：右边红色立方体是新画的

image.png

目录

VSC++2019+QT+OpenGL
QT+OpenGL一之绘制立方体（三角形图元）
QT+OpenGL二之纹理贴图
QT+OpenGL三之矩阵简解
QT+OpenGL四之相机的移动和旋转
QT+OpenGL五之绘制不同的模型（vao,vbo机制）
QT+OpenGL六之天空盒
QT+OpenGL七之使用EBO
QT+OPenGL八之模型准备
QT+OPenGL九之模型解码
QT+OPenGL十之光照模型
QT+OPenGL十一之漫反射和镜面反射贴图
QT+OPenGL十二之定向光
QT+OPenGL十三之真正的点光源和聚光灯
QT+OPenGL十四之多光源混合的问题
QT+OPenGL十五之深度缓冲区
QT+OPenGL十六之模板缓冲区
QT+OPenGL十七帧缓冲区（离屏渲染）
QT+OPenGL十八抗锯齿
QT+OPenGL十九镜面反射效率调整
QT+OPenGL二十Gamma校正