opengl 三角纹理绘制

对上一篇的改良，使用三角形来进行快速绘制

#include "stdafx.h"#include <iostream>#include <fstream>#include <cassert>#include <gl/glew.h>#include <gl/glut.h>#pragma comment(lib, "glew32.lib")using namespace std;static GLuint txtID = 0;static GLuint vbo[3] = {0};static int angle = 0;//Vbo索引static enum {Index_Vertex = 0,Index_Texture_Coord,Index_Vertex_Element_Array,};//修改为始终绘制三角形void readBitmp24(const std::string& filename, void* &ptr, int &width, int &height, int& totals){fstream in(filename.c_str(), ios_base::in|ios_base::binary);if (!in){ptr = NULL;return;}in.seekg(0x12); //18个字节开始读取宽度和高度in.read((char*)&width, sizeof(int));in.read((char*)&height,sizeof(int));//BMP的每行按照4个字节对齐int realWidth = width;int lineLength = width*3;while (lineLength % 4 != 0)++lineLength;totals = lineLength * height;ptr = new char[totals];in.seekg(0x36); //54开始是数据，按照行读取in.read((char*)ptr, totals);//将BGR模式转换为RGB模式char *startPos = NULL,*curPos = NULL;for (int i=0; i<height; ++i){curPos = ((char*)ptr+i*lineLength);for (int j=0; j<realWidth;++j){std::swap(curPos[0], curPos[2]);curPos += 3;}}in.close();}void init(){glClearColor(0,0,0,0);glClearDepth(1.0);glPixelStorei(GL_UNPACK_ALIGNMENT,4);glEnable(GL_DEPTH_TEST);glEnable(GL_LINE_SMOOTH);glEnable(GL_POLYGON_SMOOTH);glBlendFunc(GL_ALPHA, GL_ONE_MINUS_SRC_ALPHA);glEnable(GL_BLEND);glGenTextures(1, &txtID);assert(txtID);glBindTexture(GL_TEXTURE_2D, txtID);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_R, GL_REPEAT);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);//void* oldData = NULL;void* bmpData = NULL;int width=0, height=0, totals=0,depth=0;readBitmp24("e:/test.bmp",bmpData,width, height,totals);assert(bmpData);//客户端数据，暂时不释放glEnable(GL_TEXTURE_2D);glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, width, height,  0, GL_RGB, GL_UNSIGNED_BYTE, bmpData);GLenum ffff = glGetError();glBindTexture(GL_TEXTURE_2D, 0);//校验结果assert(glGetError() == GLEW_NO_ERROR);GLfloat txtCoords[][2]={{0,0},{0,1},{1,1},{1,0},};GLfloat vertex[12] = {0};//VBO buffersglGenBuffers(3,vbo);//顶点glBindBuffer(GL_ARRAY_BUFFER, vbo[Index_Vertex]);glBufferData(GL_ARRAY_BUFFER, sizeof(GLfloat)*12, vertex, GL_STATIC_DRAW);glVertexPointer(3, GL_FLOAT, 0, 0);glEnableClientState(GL_VERTEX_ARRAY);glBindBuffer(GL_ARRAY_BUFFER, 0);//纹理坐标glBindBuffer(GL_ARRAY_BUFFER, vbo[Index_Texture_Coord]);glBufferData(GL_ARRAY_BUFFER, sizeof(txtCoords), txtCoords, GL_STATIC_DRAW);glTexCoordPointer(2, GL_FLOAT, 0, 0);glEnableClientState(GL_TEXTURE_COORD_ARRAY);glBindBuffer(GL_ARRAY_BUFFER, 0);GLenum errorInfo = glGetError();assert(glGetError() == GLEW_NO_ERROR);delete[] bmpData;}void reshape(int width, int height){glViewport(0, 0, width, height);float factor = width*1.0/height;glMatrixMode(GL_PROJECTION);glLoadIdentity();gluPerspective(60, factor, 1, 10);glMatrixMode(GL_MODELVIEW);glLoadIdentity();}void display(){glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);glLoadIdentity();glTranslatef(0,0,-3);glRotatef(angle,1,1,0);glColor4f(1,1,1,0.8);//顶点static GLfloat vertexs[][3] = {{-1, -1, -1},{-1, 1, -1},{1, 1, -1},{1, -1, -1},{-1, -1, 1},{-1, 1, 1},{1, 1, 1},{1, -1, 1},};//面索引static GLubyte indices[][4] ={{3,2,1,0},{7,6,2,3},{4,5,6,7},{0,1,5,4},{5,1,2,6},{0,4,7,3},};static const int rectCnt = sizeof(indices)/4;glBindTexture(GL_TEXTURE_2D, txtID);glBindBuffer(GL_ARRAY_BUFFER, vbo[Index_Vertex]);GLfloat* mapBuffer = 0;for (int i=0; i<rectCnt; ++i){mapBuffer = (GLfloat*)glMapBuffer(GL_ARRAY_BUFFER, GL_READ_WRITE);for (int j=0; j<4; ++j){mapBuffer[j*3] = vertexs[indices[i][j]] [0];mapBuffer[j*3+1] = vertexs[indices[i][j]] [1];mapBuffer[j*3+2] = vertexs[indices[i][j]] [2];}glUnmapBuffer(GL_ARRAY_BUFFER);glDrawArrays(GL_TRIANGLE_FAN, 0,4);}glBindBuffer(GL_ARRAY_BUFFER, 0);glutSwapBuffers();}void idle(){angle += 1;angle %= 360;glutPostRedisplay();}int _tmain(int argc, _TCHAR* argv[]){glutInit(&argc, argv);glutInitDisplayMode(GLUT_DOUBLE|GLUT_RGBA|GLUT_DEPTH);glutInitWindowPosition(100, 100);glutInitWindowSize(600,600);glutCreateWindow("Texture2D");GLenum error = glewInit();assert(error == GLEW_NO_ERROR);init();glutDisplayFunc(display);glutReshapeFunc(reshape);glutIdleFunc(idle);glutMainLoop();return 0;}