GLSL记录(1)-实时旋转的三角形

    main.cpp:

#include <iostream>#include"shadertool.h"#include"glm/glm.hpp"//using namespace std;#include"glm/gtc/matrix_transform.hpp"using glm::mat4;using glm::vec3;#define PI 3.1415926GLuint vaoHandle;GLuint programHandle;float angle = 30.0f * PI/180.0f;//转换为弧度制//we create and populate the vertex buffer objects for each attributefloat positionData[] = {    -0.8f, -0.8f, .0f,    0.8f, -0.8f, 0.0f,    0.0f, 0.8f, 0.0f};float colorData[] = {    1.0f, 0.0f, 0.0f,    0.0f, 1.0f, 0.0f,    0.0f, 0.0f, 1.0f};void changeSize(int w,int h){    if(h==0)    {        h=1;    }    float ratio=1.0*w/h;    glMatrixMode(GL_PROJECTION);    glLoadIdentity();    glViewport(0,0,w,h);    gluPerspective(45,ratio,1,1000);    glMatrixMode(GL_MODELVIEW);}void renderScene(void){        glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);    angle += 0.01f;    mat4 rotationMatrix = glm::rotate( mat4(1.0f),angle,vec3(0.0f,0.0f,1.0f));    GLuint location = glGetUniformLocation( programHandle, "RotationMatrix");    if(location >= 0)    {        //printf("yes...........\n");        glUniformMatrix4fv( location, 1, GL_FALSE, &rotationMatrix[0][0]);    }    else    {        printf("no...........\n");    }    //in the render func,we bind to the vertex array obj and call glDrawArrays to initiate rendering    glBindVertexArray(vaoHandle);    glDrawArrays(GL_TRIANGLES,0,3);    glutSwapBuffers();}void processNormalKeys(unsigned char key,int x,int y){    if(key==27)    {        exit(0);    }}void setShaders(){    char* vs_code = LoadShaderFromFile("z_basic.vert");    char* fs_code = LoadShaderFromFile("z_basic.frag");    GLuint v = glCreateShader(GL_VERTEX_SHADER);//create shader obj,返回一个handle    GLuint f = glCreateShader(GL_FRAGMENT_SHADER);    const char* ff = fs_code;    const char* vv = vs_code;    /*    load the source code into shader obj,第三个参数可以是一个字符串数组，可以载入多个文件string    第二个参数是表示string array 的size,one string ,so 1.    最后一个参数表示each source code string is terminated by a null character.    一旦这个函数返回后，表明source code 已经被成功加载在opengl的内部内存，因此，之前的用来存储shader code的字符串变量    可以被释放掉了    */    glShaderSource(v,1,&vv,NULL);    glShaderSource(f,1,&ff,NULL); //    //free the source code    free(vs_code);    free(fs_code);    //next step:    //compile shader and log error    CompileShader(v,0);    CompileShader(f,1);    //final step : shaders must be linked togehter into a shader program object.    programHandle = glCreateProgram();//create a empty program obj    glAttachShader(programHandle,f);    glAttachShader(programHandle,v);    //link.can use glGetProgramiv to query status(GL_TRUE/GL_FALSE)->glGetProgramiv(GL_LINK_STATUS)    glLinkProgram(programHandle);    //install the program into the opengl pipeline    glUseProgram(programHandle);    //}void InitGL(int argc,char* argv[]){    //    glutInit(&argc,argv);    //初始化glut,必须调用，复制黏贴这句话即可    glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE ); //设置显示方式，RGB、双缓冲    glutInitWindowPosition(100,100);   //位置    glutInitWindowSize(400,400);//窗口大小    glutCreateWindow("GLSL FUN!");  //创建窗口，设置标题    glutDisplayFunc(renderScene);  // 当绘制窗口时调用myDisplay    glutIdleFunc(renderScene);    glutReshapeFunc(changeSize);    glutKeyboardFunc(processNormalKeys);    glEnable(GL_DEPTH_TEST);    glClearColor(1.0,1.0,1.0,1.0);//清除颜色设置为白色，这样glclear后面clear color就用白色clear    glewInit();    //    //1.创建    //create and populate the buffer objects    GLuint vboHandles[2];    glGenBuffers(2, vboHandles);    GLuint positionBufferHandle = vboHandles[0];    GLuint colorBufferHandle = vboHandles[1];    //2.    //populate the position buffer    glBindBuffer( GL_ARRAY_BUFFER, positionBufferHandle);    glBufferData( GL_ARRAY_BUFFER, 9 * sizeof(float), positionData, GL_STATIC_DRAW);    //populate color buffer    glBindBuffer( GL_ARRAY_BUFFER, colorBufferHandle);    //最后一个参数告诉我们这个数据是用来干嘛的，static表示不能再被修改    glBufferData( GL_ARRAY_BUFFER, 9 * sizeof(float), colorData, GL_STATIC_DRAW);    //3.create and set up the vertex array objects    glGenVertexArrays(1, &vaoHandle);    glBindVertexArray( vaoHandle );    //enable the vertex attribute arrays    glEnableVertexAttribArray(0);//vertex position    glEnableVertexAttribArray(1);//vertex color    //map index 0 to the position buffer    glBindBuffer( GL_ARRAY_BUFFER, positionBufferHandle);    glVertexAttribPointer(0,3,GL_FLOAT, GL_FALSE, 0 ,NULL);    //map index 1 to the color buffer    glBindBuffer(GL_ARRAY_BUFFER, colorBufferHandle);    glVertexAttribPointer(1,3,GL_FLOAT, GL_FALSE, 0 ,NULL);}int main(int argc,char* argv[]){    //1.    InitGL(argc,argv);    //2.    setShaders();    //3.   // LogGLVersion();    glutMainLoop();  //消息循环    //    //check gl version    return 0;}

着色器：

z_basic.vert:

#version 430/*the main opengl program refers to vertex attributes by associating each input variable with a generic attribute index.those index are simply integers between 0 and GL_MAX_VERTEX_ATTRIBS - 1.we  can specify the relationship between these indices and the attributes using the layout qualifier.*///inputlayout (location=0) in vec3 VertexPosition;layout (location=1) in vec3 VertexColor;//outputout vec3 Color;/*uniform variables are uintended to used for data that may change relatively infrequently compared to per-vertex attributes.uniform variables are well suited for the matrics used for modeling , viewing, and projective transformations.*/uniform mat4 RotationMatrix;void main(){Color = VertexColor;gl_Position = RotationMatrix * vec4 ( VertexPosition, 1.0);}

z_basic.frag:

#version 430

in vec3 Color;

layout (location = 0) out vec4 FragColor;

void main()
{
    FragColor = vec4(Color, 1.0);
}

shadertool.cpp:

#include"shadertool.h"char* LoadShaderFromFile( char* fileName){    FILE *fp;    char* content = NULL;    int count= 0;    if( fileName != NULL)    {        fp = fopen(fileName,"rt");        if(fp != NULL)        {            fseek( fp, 0, SEEK_END);            count = ftell(fp);            rewind(fp);            if(count > 0)            {                content = (char*)malloc( sizeof(char)*(count + 1));                count = fread(content,sizeof(char),count,fp);                content[count] = '\0';            }            fclose(fp);        }    }    return content;}//compile shader and if error log it.void CompileShader(GLuint s,int type){    glCompileShader(s);   //编译shader    //get compile info and log it    GLint result;    //query compile status info by call this func.    glGetShaderiv( s, GL_COMPILE_STATUS, &result);    //if false , query the shader log    if( GL_FALSE == result)    {        if(type == 0 )        fprintf(stderr,"vertex shader compile failed\n");        else fprintf(stderr,"fragment shader compile failed\n");        GLint logLen;        glGetShaderiv( s, GL_INFO_LOG_LENGTH,&logLen);        if( logLen > 0)        {            char* log = new char[ logLen ];            GLsizei written;            glGetShaderInfoLog(s,logLen, &written, log);            fprintf( stderr, "shader log : \n%s",log);            delete[] log;//free the memeory        }        else        {             fprintf( stderr, "log length <= 0");        }    }}void LogGLVersion(){    const GLubyte *renderer = glGetString(GL_RENDERER);    const GLubyte *vendor = glGetString(GL_VENDOR);    const GLubyte *version = glGetString(GL_VERSION);    const GLubyte *glslVersion = glGetString(GL_SHADING_LANGUAGE_VERSION);    GLint major, minor;    glGetIntegerv(GL_MAJOR_VERSION, &major);    glGetIntegerv(GL_MINOR_VERSION, &minor);    printf("GL Vendor               :%s\n",vendor);    printf("GL Render               :%s\n",renderer);    printf("GL Version string       :%s\n",version);    printf("GL Version int          :%d.%d\n",major,minor);    printf("GLSL Version            :%s\n",glslVersion);}

效果：