[英]OpenGL: Generating a 2D texture from a data array to display on a quad
I have written a program which performs finite-difference time-domain calculations on a 2D grid. 我编写了一个在2D网格上执行时域有限差分计算的程序。 I am looking to take the magnitude data of one of the field components (let's say the z-component of the magnetic field, Hz), convert the magnitudes into a color scale, then display the final color map on the screen.
我正在寻找一个场分量(例如,磁场的z分量,Hz)的幅度数据,将幅度转换为色标,然后在屏幕上显示最终的颜色图。 The following picture in the imgur link was generated via matlab, but I would like to accomplish the same type of image in OpenGL.
imgur链接中的以下图片是通过matlab生成的,但是我想在OpenGL中完成相同类型的图片。
http://imgur.com/8Rj77MK http://imgur.com/8Rj77MK
I am using GLFW to create the OpenGL window (800x480) with an orthographic projection using the following code: 我正在使用GLFW使用以下代码通过正交投影创建OpenGL窗口(800x480):
//-->Construct GLFW Window<--//
int WINDOW_WIDTH = 800*(xIndex/4000);
int WINDOW_HEIGHT = 480*(yIndex/2400);
GLFWwindow* window;
window = glfwCreateWindow(WINDOW_WIDTH, WINDOW_HEIGHT, "Hz Component Magnitude", NULL, NULL);
//GLFW terminate and error function setup not shown
glfwMakeContextCurrent(window);
glfwSetKeyCallback(window, key_callback);
glewInit();
glfwGetFramebufferSize(window, &WINDOW_WIDTH, &WINDOW_HEIGHT);
glViewport(0, 0, WINDOW_WIDTH, WINDOW_HEIGHT);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
//Create orthographic view
glMatrixMode(GL_PROJECTION);
glOrtho(0, 0, -1.f, 1.f, 1.f, -1.f);
glMatrixMode(GL_MODELVIEW);
glEnable(GL_TEXTURE_2D);
glLoadIdentity();
glfwSwapBuffers(window);
glfwPollEvents();
//-->END Construct GLFW Window<--//
The color data for the Hz field is stored by: Hz字段的颜色数据通过以下方式存储:
From what I have read, the typical way to display a 2D texture in a window is to create a quad and apply the texture to the quad. 据我了解,在窗口中显示2D纹理的典型方法是创建一个四边形并将纹理应用于四边形。 I can successfully create the quad, and have successfully generated the color data (verified with matlab), but I am having trouble creating the texture to apply to the quad.
我可以成功创建四边形,并且已经成功生成了颜色数据(已通过matlab验证),但是我无法创建要应用于四边形的纹理。
My code to generate the texture is: 我生成纹理的代码是:
int num_colors = 3; //Number of colors per pixel
int tex_size = num_colors*WINDOW_WIDTH*WINDOW_HEIGHT; //Number of entries in tex_Hz
int size = tex_size*sizeof(int);
//Create pointer for storing color map
int* tex_Hz = (int*)malloc(size);
for(int i = 0; i < tex_size; i++) //Initialize colormap to 0
tex_Hz[i] = 0;
//OpenCL buffer for the color map
cl::Buffer texture_mem(context, CL_MEM_READ_WRITE | CL_MEM_COPY_HOST_PTR, size, tex_Hz, &error);
//Generate a texture ID
GLuint tex_id;
glGenTextures(1, &tex_id);
glBindTexture(GL_TEXTURE_2D, tex_id);
//*A bunch of irrelevant code*//
//-->Start of time loop<--//
//*A bunch of irrelevant code*//
//-->Update the Hz field<--//
time_loop_queue.enqueueNDRangeKernel(timeLoopKernels[1], 0, global_size, local_size);
time_loop_queue.finish();
//-->Generate 2D image every 100 time steps<--//
if(step%100 == 0)
{
//Read colormap values from OpenCL buffer
time_loop_queue.enqueueReadBuffer(texture_mem, NULL, 0, size, tex_Hz, NULL, NULL);
time_loop_queue.finish();
//Used only as a debug runtime check to make sure data copied back
cout << tex_Hz[3*800*240 + 3*350] << "\n";
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, WINDOW_WIDTH, WINDOW_HEIGHT, 0, GL_RGB, GL_INT, tex_Hz);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glLoadIdentity();
glBindTexture(GL_TEXTURE_2D, tex_id);
//Draw quad and set texture coords
glBegin(GL_QUADS);
glTexCoord2d(0.0,0.0); glVertex2d(-1.0,-1.0);
glTexCoord2d(1.0,0.0); glVertex2d(1.0,-1.0);
glTexCoord2d(1.0,1.0); glVertex2d(1.0,1.0);
glTexCoord2d(0.0,1.0); glVertex2d(-1.0,1.0);
glEnd();
glfwSwapBuffers(window);
}
The problem which occurs is that the quad remains black. 发生的问题是四边形保持黑色。
***I know copying data back into host memory to then create a GL texture is not optimal in terms of performance, but at this point all that matters is implementing the field display on the shortest timescale possible, not achieving optimal performance (yet). ***我知道将数据复制回主机内存以创建GL纹理在性能上不是最佳的,但是目前最重要的是在尽可能短的时间范围内实现现场显示,但尚未达到最佳性能(尚未) 。
Fixed it. 修复。 When using the GL_INT flag in glTexImage2D(...) the color scale ranges over all values of a signed int , and I was using a color scale from 0-255 for each channel, which is essentially 0 using GL_INT.
当在glTexImage2D(...)中使用GL_INT标志时,色标的范围涵盖一个有符号int的所有值,并且我为每个通道使用的色标范围是0-255,使用GL_INT基本上是0。
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.