这是代码。输出始终是一个灰色方块-始终都是输入,无论输入是什么,并且它显然是错误的。我的目标是能够将所有像素存储在某个位置并显示它们,以便我可以继续使用简单的光线跟踪器,而我似乎无法弄清楚这glDrawPixels的问题。
#include <stdlib.h>
#include <GL/glut.h >
using namespace std;
struct RGBType {
float r;
float g;
float b;
//float a;
};
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
RGBType *pixels = new RGBType[250*250];
for (int x = 0; x < 250; x++) {
for (int y = 0; y < 250; y++) {
pixels->r = 0;
pixels->g = 1;
pixels->b = 1;
//pixels->a = 200;
}
}
glTexSubImage2D(GL_TEXTURE_2D,0,0,0,250,250,GL_RGB,GL_UNSIGNED_BYTE,pixels);
//glColor3f(1.0,1.0,1.0);
glBegin(GL_POLYGON);
glVertex3f(0.0, 0.0, 0.0);
glVertex3f(1.0, 0.0, 0.0);
glVertex3f(1.0, 1.0, 0.0);
glVertex3f(0.0, 1.0, 0.0);
glEnd();
glutSwapBuffers();
}
void init(void)
{
//select clearing (background) color
glClearColor(0.0, 0.0, 0.0, 0.0);
//initialize viewing values
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0.0, 1.0, 0.0, 1.0, -1.0, 1.0);
}
int main(int argc, char** argv)
{
//Initialise GLUT with command-line parameters.
glutInit(&argc, argv);
//Set Display Mode
glutInitDisplayMode(GLUT_RGB | GLUT_DOUBLE | GLUT_DEPTH);
//Set the window size
glutInitWindowSize(250,250);
//Set the window position
glutInitWindowPosition(100,100);
//Create the window
glutCreateWindow("Ray Tracer");
//Call init (initialise GLUT
init();
//Call "display" function
glutDisplayFunc(display);
//Enter the GLUT event loop
glutMainLoop();
return 0;
}
最佳答案
struct RGBType {
float r;
float g;
float b;
^^^^^^^^ all floats here...
//float a;
};
...
RGBType *pixels = new RGBType[250*250];
...
glTexSubImage2D(GL_TEXTURE_2D,0,0,0,250,250,GL_RGB,GL_UNSIGNED_BYTE,pixels);
^^^^^^^^^^^^^^^^ wat
您要告诉OpenGL将
pixels
解释为unsigned char
的数组,以four bytes组的形式读取它们,并将每四个的前三个字节用作RGB通道。不要对OpenGL说谎。最后很少为您解决问题。
请尝试
GL_FLOAT
。并首先创建一个实际的纹理对象。
在尝试向其上载数据之前,请绑定(bind)该纹理对象。
并为多边形指定一些纹理坐标。
并在绘制多边形之前启用纹理。
像这样:
#include <GL/glut.h>
struct RGBType
{
float r;
float g;
float b;
};
GLuint tex = 0;
void init()
{
RGBType pixels[ 250*250 ];
RGBType* temp = pixels;
for (int x = 0; x < 250; x++)
{
for (int y = 0; y < 250; y++)
{
temp->r = 0;
temp->g = 1;
temp->b = 1;
temp++;
}
}
glGenTextures( 1, &tex );
glBindTexture( GL_TEXTURE_2D, tex );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR );
glTexParameteri( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR );
glTexImage2D( GL_TEXTURE_2D, 0, GL_RGB, 250, 250, 0, GL_RGB, GL_FLOAT, NULL );
glTexSubImage2D(GL_TEXTURE_2D,0,0,0,250,250,GL_RGB,GL_FLOAT,pixels);
}
void display(void)
{
glClearColor(0, 0, 0, 1);
glClear(GL_COLOR_BUFFER_BIT);
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-2, 2, -2, 2, -1, 1);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glColor3ub( 255, 255, 255 );
glEnable( GL_TEXTURE_2D );
glBindTexture( GL_TEXTURE_2D, tex );
glBegin(GL_QUADS);
glTexCoord2i( 0, 0 );
glVertex2i( 0, 0 );
glTexCoord2i( 1, 0 );
glVertex2i( 1, 0 );
glTexCoord2i( 1, 1 );
glVertex2i( 1, 1 );
glTexCoord2i( 0, 1 );
glVertex2i( 0, 1 );
glEnd();
glutSwapBuffers();
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE);
glutInitWindowSize(250,250);
glutCreateWindow("Ray Tracer");
init();
glutDisplayFunc(display);
glutMainLoop();
return 0;
}
关于c++ - 为什么glDrawPixels在这里不起作用?,我们在Stack Overflow上找到一个类似的问题:https://stackoverflow.com/questions/20009471/