我的程序显示从带有openGL的网络摄像头加载openCV的图像。
下面的程序通常有效但我在代码后面列出了一些问题。
主：
#define GLEW_STATIC
#include <GL/glew.h>
#include <GLFW\glfw3.h>
#include <iostream>
#include <fstream> //std::ifstream
#include <algorithm> //std::max()
#include <opencv2\core\core.hpp>
#include <opencv2\highgui\highgui.hpp>
cv::VideoCapture capture0;
cv::VideoCapture capture1;
void captureFromWebcam(cv::Mat &frame, cv::VideoCapture &capture)
{
capture.read(frame);
}
bool initializeCapturing()
{
capture0.open(0);
capture1.open(1);
if(!capture0.isOpened() | !capture1.isOpened())
{
std::cout << "Ein oder mehrere VideoCaptures konnten nicht geöffnet werden" << std::endl;
if(!capture0.isOpened())
capture0.release();
if(!capture1.isOpened())
capture1.release();
return false;
}
return true;
}
void releaseCapturing()
{
capture0.release();
capture1.release();
}
GLuint LoadShaders(const char * vertex_file_path,const char * fragment_file_path){
// Create the shaders
GLuint VertexShaderID = glCreateShader(GL_VERTEX_SHADER);
GLuint FragmentShaderID = glCreateShader(GL_FRAGMENT_SHADER);
// Read the Vertex Shader code from the file
std::string VertexShaderCode;
std::ifstream VertexShaderStream(vertex_file_path, std::ios::in);
if(VertexShaderStream.is_open())
{
std::string Line = "";
while(getline(VertexShaderStream, Line))
VertexShaderCode += "\n" + Line;
VertexShaderStream.close();
}
// Read the Fragment Shader code from the file
std::string FragmentShaderCode;
std::ifstream FragmentShaderStream(fragment_file_path, std::ios::in);
if(FragmentShaderStream.is_open()){
std::string Line = "";
while(std::getline(FragmentShaderStream, Line))
FragmentShaderCode += "\n" + Line;
FragmentShaderStream.close();
}
GLint Result = GL_FALSE;
int InfoLogLength;
// Compile Vertex Shader
printf("Compiling shader : %s\n", vertex_file_path);
char const * VertexSourcePointer = VertexShaderCode.c_str();
glShaderSource(VertexShaderID, 1, &VertexSourcePointer , NULL);
glCompileShader(VertexShaderID);
// Check Vertex Shader
glGetShaderiv(VertexShaderID, GL_COMPILE_STATUS, &Result);
glGetShaderiv(VertexShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
std::vector<char> VertexShaderErrorMessage(InfoLogLength);
glGetShaderInfoLog(VertexShaderID, InfoLogLength, NULL, &VertexShaderErrorMessage[0]);
fprintf(stdout, "%s\n", &VertexShaderErrorMessage[0]);
// Compile Fragment Shader
printf("Compiling shader : %s\n", fragment_file_path);
char const * FragmentSourcePointer = FragmentShaderCode.c_str();
glShaderSource(FragmentShaderID, 1, &FragmentSourcePointer , NULL);
glCompileShader(FragmentShaderID);
// Check Fragment Shader
glGetShaderiv(FragmentShaderID, GL_COMPILE_STATUS, &Result);
glGetShaderiv(FragmentShaderID, GL_INFO_LOG_LENGTH, &InfoLogLength);
std::vector<char> FragmentShaderErrorMessage(InfoLogLength);
glGetShaderInfoLog(FragmentShaderID, InfoLogLength, NULL, &FragmentShaderErrorMessage[0]);
fprintf(stdout, "%s\n", &FragmentShaderErrorMessage[0]);
// Link the program
fprintf(stdout, "Linking program\n");
GLuint ProgramID = glCreateProgram();
glAttachShader(ProgramID, VertexShaderID);
glAttachShader(ProgramID, FragmentShaderID);
glLinkProgram(ProgramID);
// Check the program
glGetProgramiv(ProgramID, GL_LINK_STATUS, &Result);
glGetProgramiv(ProgramID, GL_INFO_LOG_LENGTH, &InfoLogLength);
std::vector<char> ProgramErrorMessage( std::max(InfoLogLength, int(1)) );
glGetProgramInfoLog(ProgramID, InfoLogLength, NULL, &ProgramErrorMessage[0]);
fprintf(stdout, "%s\n", &ProgramErrorMessage[0]);
glDeleteShader(VertexShaderID);
glDeleteShader(FragmentShaderID);
return ProgramID;
}
int main ()
{
int w = 640,h=480;
glfwInit();
//configure glfw
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3);
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 2);
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE);
glfwWindowHint(GLFW_OPENGL_FORWARD_COMPAT, GL_TRUE);
glfwWindowHint(GLFW_RESIZABLE, GL_FALSE);
GLFWwindow* window = glfwCreateWindow(w, h, "OpenGL", NULL, nullptr); // windowed
glfwMakeContextCurrent(window);
glewExperimental = GL_TRUE;
glewInit();
initializeCapturing();
GLuint VertexArrayID;
glGenVertexArrays(1, &VertexArrayID);
glBindVertexArray(VertexArrayID);
// An array of 3 vectors which represents 3 vertices (singular: vertex -> ein Punkt im dreidimensionalen raum)
static const GLfloat g_vertex_buffer_data[] = {
//x,y,z
-1.0f, -1.0f, 0.0f, //unten links
1.0f, 1.0f, 0.0f, //oben rechts
-1.0f, 1.0f, 0.0f, //oben links
-1.0f, -1.0f, 0.0f, //unten links
1.0f, 1.0f, 0.0f, //oben rechts
1.0f,-1.0f,0.0f //unten rechts
};
static const GLfloat vertex_buffer_coordinates[] ={
0.0f,0.0f,
1.0f,1.0f,
0.0f,1.0f,
0.0f,0.0f,
1.0f,1.0f,
1.0f,0.0f,
};
GLuint coordinateBuffer;
glGenBuffers(1,&coordinateBuffer);
glBindBuffer(GL_ARRAY_BUFFER, coordinateBuffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(vertex_buffer_coordinates), vertex_buffer_coordinates, GL_STATIC_DRAW);
// This will identify our vertex buffer
GLuint vertexbuffer;
// Generate 1 buffer, put the resulting identifier in vertexbuffer
glGenBuffers(1, &vertexbuffer);
// The following commands will talk about our 'vertexbuffer' buffer
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
// Give our vertices to OpenGL.
glBufferData(GL_ARRAY_BUFFER, sizeof(g_vertex_buffer_data), g_vertex_buffer_data, GL_STATIC_DRAW);
GLuint shader_programm = LoadShaders("vertex.shader","fragment.shader");
GLuint tex;
glGenTextures(1, &tex);
glBindTexture(GL_TEXTURE_2D, tex);
//was passiert wenn die texture koordinaten außerhalb des bereichs sind?
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
//was passiert wenn die textur gestreckt/gestaucht wird?
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
cv::Mat frame;
captureFromWebcam(frame,capture0);
glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA,frame.size().width,frame.size().height,0,GL_RGB,GL_UNSIGNED_BYTE,frame.data);
glUniform1i(glGetUniformLocation(shader_programm, "myTextureSampler"), 0);
while(!glfwWindowShouldClose(window))
{
glfwPollEvents();
if (glfwGetKey(window, GLFW_KEY_ESCAPE) == GLFW_PRESS)
glfwSetWindowShouldClose(window, GL_TRUE);
// 1rst attribute buffer : vertices
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, vertexbuffer);
glVertexAttribPointer(
0, // attribute 0. No particular reason for 0, but must match the layout in the shader.
3, // size
GL_FLOAT, // type
GL_FALSE, // normalized?
0, // stride
(void*)0 // array buffer offset
);
// 2nd attribute buffer : colors
glEnableVertexAttribArray(1);
glBindBuffer(GL_ARRAY_BUFFER, coordinateBuffer);
glVertexAttribPointer(
1, // attribute. No particular reason for 1, but must match the layout in the shader.
3, // size
GL_FLOAT, // type
GL_FALSE, // normalized?
0, // stride
(void*)0 // array buffer offset
);
const GLfloat color[] = {0.0f,0.2f,0.0f,1.0f};
glClearBufferfv(GL_COLOR,0,color);
glUseProgram(shader_programm);
// Draw the triangle !
glDrawArrays(GL_TRIANGLES, 0, 2*3); // Starting from vertex 0; 3 vertices total -> 1 triangle
//glDrawArrays(GL_POINTS,0,1);
glDisableVertexAttribArray(0);
glDisableVertexAttribArray(1);
glfwSwapBuffers(window);
}
glDeleteVertexArrays(1,&VertexArrayID);
glDeleteProgram(shader_programm);
glDeleteVertexArrays(1,&VertexArrayID);
releaseCapturing();
glfwTerminate();
return 1;
}
顶点着色器：
#version 330 core
layout (location = 0) in vec3 vertexPosition_modelspace; //input vom vertexbuffer
layout (location = 1) in vec2 UVcoord;
out vec2 UV;
void main(void)
{
gl_Position.xyz = vertexPosition_modelspace;
gl_Position.w = 1.0; //Zoomfaktor
UV = UVcoord;
}
片段着色器：
#version 330 core
in vec2 UV;
out vec4 color;
// Values that stay constant for the whole mesh.
uniform sampler2D myTextureSampler;
void main(void)
{
//color = texture2D(myTextureSampler,UV);
color = texelFetch(myTextureSampler,ivec2(gl_FragCoord.xy),0);
}
答案 0 :(得分：2)
GLSL texture地址使用标准化坐标，即[0,1]范围内的值，并执行过滤。 texelFetch通过特定mipmap级别的绝对像素索引进行地址，而不会过滤。
根据您的屏幕截图判断您传递给texture的纹理坐标是错误的，还是错误处理的; texelFetch代码不使用显式指定的纹理协调，而是使用视口像素坐标。
查看glVertexAttribPointer的纹理坐标调用，告诉OpenGL每个纹理坐标有3个元素，而数组只有2个。这可能是你的问题。
