我在正确绘制正方形时遇到了麻烦。我在 Windows 7 x64 上使用 glut 和 glew。
我只能在右上角看到一个黑色方块（我的应用程序中的 WALL）。
我正在尝试用正方形画一个迷宫。
我没有着色器的源代码：
#define GL_GLEXT_PROTOTYPES 1
#define FREEGLUT_LIB_PRAGMAS 1
#define FREEGLUT_STATIC 1
#include <gl/glew.h>
#include <gl/freeglut.h>
#include <stdlib.h>
#include <gl/glext.h>
#include "Shaders.h"
#include <iostream>
using namespace std;
GLuint buf_v;
GLuint buf_c;
#define FOR(i,s,t) for(int i = (s); i < (t);i++)
int width = 480;
int height = 800;
const int N = 24;
const int WALL = 9999;
int map[N][N];
GLfloat arrQuad[12];
GLfloat color[] ={ 1.0,1.0,1.0,1.0};
Shaders shaders;
Matrix w, v, p, wvp;
void drawQuad(float x, float y, int isWALL = 9999){//from top left corner
glUseProgram(shaders.program);
glBindBuffer(GL_ARRAY_BUFFER, buf_v);
GLvoid *buf = glMapBuffer(GL_ARRAY_BUFFER, GL_WRITE_ONLY );
arrQuad[0] = x;
arrQuad[1] = y;
arrQuad[2] = x;
arrQuad[3] = y + 1.0;
arrQuad[4] = x + 1.0;
arrQuad[5] = y;
arrQuad[6] = x;
arrQuad[7] = y + 1.0;
arrQuad[8] = x + 1.0;
arrQuad[9] = y;
arrQuad[10] = x + 1.0;
arrQuad[11] = y + 1.0;
FOR(i,0,12){
arrQuad[i]*=(GLfloat)width;
arrQuad[i]/=(GLfloat)N;
}
printf("%f, %f %f %f \n",arrQuad[3],arrQuad[4], arrQuad[10],arrQuad[11]);
printf("%f, %f %f %f \n\n",arrQuad[0],arrQuad[1], arrQuad[8],arrQuad[9]);
memcpy(buf, arrQuad, sizeof(arrQuad));
glUnmapBuffer(GL_ARRAY_BUFFER);
if(isWALL == WALL){
color[0] = 1.0f; color[1] = 1.0f; color[2] = 1.0f;
}
else
{
color[0] = 0.0; color[1] = 0.0; color[2] = 0.0;
}
if(shaders.positionAttribute != -1)
{
glEnableVertexAttribArray(shaders.positionAttribute);
glVertexAttribPointer(shaders.positionAttribute, 2, GL_FLOAT, GL_FALSE, 0, 0);;
}else{ perror("err pos attr"); }
if(shaders.colorUniform != -1)
{
glUniform4fv(shaders.colorUniform, 1, color);
}else{ perror ("err col atr"); }
GLfloat mat_wvp_16[16] = {
wvp[0], wvp[1], wvp[2], wvp[3],
wvp[4], wvp[5], wvp[6], wvp[7],
wvp[8], wvp[9], wvp[10], wvp[11],
wvp[12], wvp[13], wvp[14], wvp[15],
};
if(shaders.mat_wvp != -1)
{
glUniformMatrix4fv(shaders.mat_wvp, 1, GL_FALSE, mat_wvp_16);
}else{
//perror ("err mat atr");
}
glBindBuffer(GL_ARRAY_BUFFER, buf_v);
glDrawArrays(GL_TRIANGLES, 0, 6);
glBindBuffer(GL_ARRAY_BUFFER, 0);
}
void reshape(int w, int h)
{
glViewport(0,0,(GLsizei)w,(GLsizei)h);
}
void init(){
shaders.HasGLSLSupport();
glEnableClientState(GL_VERTEX_ARRAY);
glEnableClientState(GL_COLOR_ARRAY);
glGenBuffers(1, &buf_v);
glBindBuffer(GL_ARRAY_BUFFER, buf_v);
glBufferData(GL_ARRAY_BUFFER, sizeof(arrQuad), arrQuad, GL_DYNAMIC_DRAW);
glGenBuffers(1, &buf_c);
glBindBuffer(GL_ARRAY_BUFFER, buf_c);
glBufferData(GL_ARRAY_BUFFER, sizeof(color), color, GL_DYNAMIC_DRAW);
glBindBuffer(GL_ARRAY_BUFFER, 0);
if(shaders.Init("vert.vs","frag.frg") != 0)
perror("shader initialization error");
wvp.loadOrthoMatrix(0.0, width, 0, height, 0.0, 100.0);
wvp = wvp * w;
}
void display()
{
glClear(GL_COLOR_BUFFER_BIT);
FOR(i, 0, N)
FOR(j, 0, N)
{
drawQuad(i, j, map[i][j]);
}
glutSwapBuffers();
}
void timer(int i = 0)
{
glutPostRedisplay();
FOR(i, 0, N)
FOR(j, 0, N)
{
if(rand() % 4 == 0)
map[i][j] = WALL;
else
map[i][j] = -1;
}
display();
}
int main(int argc, char **argv)
{
glutInit( &argc, argv);
glutInitDisplayMode(GLUT_DOUBLE | GLUT_RGBA);
glutInitWindowSize(width, height);
glutCreateWindow("Hi, wave!");
glClearColor(1.0,1.0,1.0,1.0);
glViewport(0,0,(GLfloat)width, (GLfloat)height);
GLenum err = glewInit();
if (GLEW_OK != err)
{
cout << "glewInit failed, aborting." << endl;
exit (1);
}
init();
glutTimerFunc(17,timer,0);
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutMainLoop();
return 0;
}
vert.vs
uniform mat4 u_wvp;
attribute vec4 a_pos;
void main ()
{
gl_Position = (u_wvp * a_pos);
}
片段
precision mediump float;
uniform vec4 u_color;
void main(){
gl_FragColor = u_color;
}