Opengl 无法使用 glColor3f(1.0f, 0.0f, 0.0f) 非常不透明的红色将颜色设置为纯色
Opengl Cant set color to solid with glColor3f(1.0f, 0.0f, 0.0f) very opaque red
图像显示为红色不透明，但我设置了 glColor3f(1.0f, 0.0f, 0.0f);
//command compiler g++ console tested with Visual Studio Code
//g++ GL01Hello.cpp -o GL01Hello.exe -L"C:/MinGW/freeglut/lib" -lglu32 -lopengl32 -lfreeglut -I"C:\MinGW\freeglut\include\GL"
/*
* GL01Hello.cpp:With Load Background Image and Poligon Test OpenGL/GLUT C/C++ Setup
* Tested Visual Studio Code with MinGW
* To compile with -lfreeglut -lglu32 -lopengl32 and
*/
#include <windows.h> // for MS Windows
#include <stdio.h> /* printf, scanf, puts, NULL */
#include <iostream>
#include <stdlib.h> /* srand, rand */
#include <ctime>
#include <freeglut.h> // GLUT, include glu.h and gl.h
using namespace std;
float spin = 0.0;
GLuint texture = 0;
int w1 = 0;
int h1 = 0;
// for random color primitive polygon
//static GLubyte redc,greenc,bluec;
bool prim_polygonmode = false;
// glut_load_image
GLuint LoadTexture( const char * filename )
{
GLuint texture;
int width, height;
unsigned char * data;
FILE * file;
file = fopen( filename, "rb" );
if(!file)
std::cout<<"File not Found"<<std::endl;
if ( file == NULL ) return 0;
width = 1360;
height = 768;
data = (unsigned char *)malloc( width * height * 3 );
//int size = fseek(file,);
fread( data, width * height * 3, 1, file );
fclose( file );
for(int i = 0; i < width * height ; ++i)
{
int index = i*3;
unsigned char B,R;
B = data[index];
R = data[index+2];
data[index] = R;
data[index+2] = B;
}
glGenTextures( 1, &texture );
glBindTexture( GL_TEXTURE_2D, texture );
glPixelStorei( GL_UNPACK_ALIGNMENT, 1 );//Necessary for correct elements value 4 default
glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE,GL_MODULATE );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_LINEAR_MIPMAP_NEAREST );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,GL_LINEAR );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,GL_REPEAT );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,GL_REPEAT );
gluBuild2DMipmaps( GL_TEXTURE_2D, 3, width, height,GL_RGB, GL_UNSIGNED_BYTE, data );
free( data );
return texture;
}
/* Initialize OpenGL Graphics just n this case for colors */
void initGL() {
// Set "clearing" or background color
glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // Black and opaque
//randomnumber color by ctime library
srand(time(NULL));
//redc = rand()%255;
//greenc = rand()%255;
//bluec = rand()%255;
}
/* Called back when there is no other event to be handled */
void idle() {
spin = spin + 0.075;
if (spin > 360.0)
spin = 0;
glutPostRedisplay(); // Post a re-paint request to activate display()
}
/* Handler for window re-size event. Called back when the window first appears and
whenever the window is re-sized with its new width and height */
void reshape(GLsizei width, GLsizei height) { // GLsizei for non-negative integer
// Compute aspect ratio of the new window
w1 = width;
h1 = height;
if (height == 0) height = 1; // To prevent divide by 0
GLfloat aspect = (GLfloat)width / (GLfloat)height;
// Set the viewport to cover the new window
glViewport(0, 0, width, height);
// Set the aspect ratio of the clipping area to match the viewport
glMatrixMode(GL_PROJECTION); // To operate on the Projection matrix
glLoadIdentity();
if (width >= height) {
// aspect >= 1, set the height from -1 to 1, with larger width
gluOrtho2D(-1.0 * aspect, 1.0 * aspect, -1.0, 1.0);
} else {
// aspect < 1, set the width to -1 to 1, with larger height
gluOrtho2D(-1.0, 1.0, -1.0 / aspect, 1.0 / aspect);
}
}
void orthogonalStart()
{
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
gluOrtho2D(-w1/2, w1/2, -h1/2, h1/2);
glMatrixMode(GL_MODELVIEW);
}
void orthogonalEnd()
{
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
}
void background()
{
glBindTexture( GL_TEXTURE_2D, texture );
orthogonalStart();
glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glPolygonOffset(1,1);
// texture width/height
const int iw = 1360;
const int ih = 768;
glPushMatrix();
glTranslatef( -iw/2, -ih/2, 0 );
glBegin(GL_QUADS);
glColor3f(1.0f, 1.0f, 1.0f); // always default color white stars, if no this line will random color same of polygon
glTexCoord2i(0,0); glVertex2i(0, 0);
glTexCoord2i(1,0); glVertex2i(iw, 0);
glTexCoord2i(1,1); glVertex2i(iw, ih);
glTexCoord2i(0,1); glVertex2i(0, ih);
glEnd();
glPopMatrix();
orthogonalEnd();
}
void display() {
glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // Set background color to black and opaque
glClear(GL_COLOR_BUFFER_BIT);// Clear the color buffer (background
glEnable( GL_TEXTURE_2D );
background();
gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
// A SQUARE PARAMETERS
if (prim_polygonmode) { // draw polygon mode lines
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
} else {
glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glPolygonOffset(1,1);
}
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glPushMatrix();
glRotatef(spin , 0., 0., 1.);
glTranslatef(50.0, 50.0, 0);
glTranslatef(-50.0, -50.0, 0);
glBegin(GL_QUADS); // Each set of 4 vertices form a quad
//glColor3ub(redc, greenc, bluec); // Random red green blue value
glColor3f(1.0f, 0.0f, 0.0f); // Random red green blue value
glVertex2f(-0.5f, -0.5f); // x, y default 0.5f values
glVertex2f( 0.5f, -0.5f);
glVertex2f( 0.5f, 0.5f);
glVertex2f(-0.5f, 0.5f);
glEnd();
//angle += 5.0f;
glPopMatrix();
// glFlush(); // Render now
glutSwapBuffers(); // Double buffered - swap the front and back buffers
}
/* Callback handler for special-key event */
void specialKeys(int key, int x, int y) {
switch (key) {
case GLUT_KEY_F1: // F1: Toggle wireframe and solid polygon
prim_polygonmode = !prim_polygonmode; // Toggle state
break;
}
}
/* Main function: GLUT runs as a console application starting at main() */
int main(int argc, char** argv) {
glutInit(&argc, argv); // Initialize GLUT
glutInitDisplayMode(GLUT_DOUBLE); // Enable double buffered mode
glutInitWindowSize(1360, 768); // Set the window's initial width & height
glutInitWindowPosition(0, 0);
// Position the window's initial top-left corner
glutCreateWindow("OpenGL Setup Test"); // Create a window with the given title
glutSpecialFunc(specialKeys); // Register callback handler for special-key event
glutDisplayFunc(display); // Register display callback handler for window re-paint
glutReshapeFunc(reshape);
glutIdleFunc(idle);
// GLuint texture;
texture = LoadTexture( "stars.bmp" );
initGL();
glutMainLoop();// Enter the event-processing loop
//Free our texture
glDeleteTextures( 1, &texture );
return 0;
}
这段代码有一组背景和方形的小动画。
不知道为什么不能设置更多纯色。然后线框正方形我得到了一条非常小的红色线需要得到明亮的颜色 red.Maybe 任何过滤器，你的缓冲区导致了那个？
如果可能请帮助我。
OpenGL 是一个状态引擎。一旦设置了状态，它就会一直存在，直到再次更改为止。
这意味着如果启用二维纹理，则以下所有几何体都是 "textured".
注意，当调用glVertex2f时，当前纹理坐标与顶点坐标相关联。如果您没有明确设置纹理坐标，那么最后设置的纹理坐标仍然是当前纹理坐标，并且将关联到顶点坐标。这可能会导致类似随机行为。
如果启用纹理，则默认情况下纹理元素的颜色乘以当前颜色，因为默认情况下纹理环境模式 (GL_TEXTURE_ENV_MODE) 为 GL_MODULATE。参见 glTexEnv。
这意味着：
如果您想绘制带有纹理的几何图形，请启用纹理并设置 "white" 颜色：
glEnable(GL_TEXTURE_2D)
glColor3f(1.0f, 1.0f, 1.0f);
background();
如果要绘制颜色统一的几何图形，请设置颜色并禁用纹理：
glDisable(GL_TEXTURE_2D);
glColor3f(1.0f, 0.0f, 0.0f);
glBegin(GL_QUADS);
// [...]
glEnd();
图像显示为红色不透明，但我设置了 glColor3f(1.0f, 0.0f, 0.0f);
//command compiler g++ console tested with Visual Studio Code
//g++ GL01Hello.cpp -o GL01Hello.exe -L"C:/MinGW/freeglut/lib" -lglu32 -lopengl32 -lfreeglut -I"C:\MinGW\freeglut\include\GL"
/*
* GL01Hello.cpp:With Load Background Image and Poligon Test OpenGL/GLUT C/C++ Setup
* Tested Visual Studio Code with MinGW
* To compile with -lfreeglut -lglu32 -lopengl32 and
*/
#include <windows.h> // for MS Windows
#include <stdio.h> /* printf, scanf, puts, NULL */
#include <iostream>
#include <stdlib.h> /* srand, rand */
#include <ctime>
#include <freeglut.h> // GLUT, include glu.h and gl.h
using namespace std;
float spin = 0.0;
GLuint texture = 0;
int w1 = 0;
int h1 = 0;
// for random color primitive polygon
//static GLubyte redc,greenc,bluec;
bool prim_polygonmode = false;
// glut_load_image
GLuint LoadTexture( const char * filename )
{
GLuint texture;
int width, height;
unsigned char * data;
FILE * file;
file = fopen( filename, "rb" );
if(!file)
std::cout<<"File not Found"<<std::endl;
if ( file == NULL ) return 0;
width = 1360;
height = 768;
data = (unsigned char *)malloc( width * height * 3 );
//int size = fseek(file,);
fread( data, width * height * 3, 1, file );
fclose( file );
for(int i = 0; i < width * height ; ++i)
{
int index = i*3;
unsigned char B,R;
B = data[index];
R = data[index+2];
data[index] = R;
data[index+2] = B;
}
glGenTextures( 1, &texture );
glBindTexture( GL_TEXTURE_2D, texture );
glPixelStorei( GL_UNPACK_ALIGNMENT, 1 );//Necessary for correct elements value 4 default
glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE,GL_MODULATE );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,GL_LINEAR_MIPMAP_NEAREST );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,GL_LINEAR );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_S,GL_REPEAT );
glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_WRAP_T,GL_REPEAT );
gluBuild2DMipmaps( GL_TEXTURE_2D, 3, width, height,GL_RGB, GL_UNSIGNED_BYTE, data );
free( data );
return texture;
}
/* Initialize OpenGL Graphics just n this case for colors */
void initGL() {
// Set "clearing" or background color
glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // Black and opaque
//randomnumber color by ctime library
srand(time(NULL));
//redc = rand()%255;
//greenc = rand()%255;
//bluec = rand()%255;
}
/* Called back when there is no other event to be handled */
void idle() {
spin = spin + 0.075;
if (spin > 360.0)
spin = 0;
glutPostRedisplay(); // Post a re-paint request to activate display()
}
/* Handler for window re-size event. Called back when the window first appears and
whenever the window is re-sized with its new width and height */
void reshape(GLsizei width, GLsizei height) { // GLsizei for non-negative integer
// Compute aspect ratio of the new window
w1 = width;
h1 = height;
if (height == 0) height = 1; // To prevent divide by 0
GLfloat aspect = (GLfloat)width / (GLfloat)height;
// Set the viewport to cover the new window
glViewport(0, 0, width, height);
// Set the aspect ratio of the clipping area to match the viewport
glMatrixMode(GL_PROJECTION); // To operate on the Projection matrix
glLoadIdentity();
if (width >= height) {
// aspect >= 1, set the height from -1 to 1, with larger width
gluOrtho2D(-1.0 * aspect, 1.0 * aspect, -1.0, 1.0);
} else {
// aspect < 1, set the width to -1 to 1, with larger height
gluOrtho2D(-1.0, 1.0, -1.0 / aspect, 1.0 / aspect);
}
}
void orthogonalStart()
{
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
gluOrtho2D(-w1/2, w1/2, -h1/2, h1/2);
glMatrixMode(GL_MODELVIEW);
}
void orthogonalEnd()
{
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
}
void background()
{
glBindTexture( GL_TEXTURE_2D, texture );
orthogonalStart();
glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glPolygonOffset(1,1);
// texture width/height
const int iw = 1360;
const int ih = 768;
glPushMatrix();
glTranslatef( -iw/2, -ih/2, 0 );
glBegin(GL_QUADS);
glColor3f(1.0f, 1.0f, 1.0f); // always default color white stars, if no this line will random color same of polygon
glTexCoord2i(0,0); glVertex2i(0, 0);
glTexCoord2i(1,0); glVertex2i(iw, 0);
glTexCoord2i(1,1); glVertex2i(iw, ih);
glTexCoord2i(0,1); glVertex2i(0, ih);
glEnd();
glPopMatrix();
orthogonalEnd();
}
void display() {
glClearColor(0.0f, 0.0f, 0.0f, 1.0f); // Set background color to black and opaque
glClear(GL_COLOR_BUFFER_BIT);// Clear the color buffer (background
glEnable( GL_TEXTURE_2D );
background();
gluLookAt (0.0, 0.0, 5.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
// A SQUARE PARAMETERS
if (prim_polygonmode) { // draw polygon mode lines
glPolygonMode(GL_FRONT_AND_BACK, GL_LINE);
} else {
glEnable(GL_POLYGON_OFFSET_FILL);
glPolygonMode(GL_FRONT_AND_BACK, GL_FILL);
glPolygonOffset(1,1);
}
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
glPushMatrix();
glRotatef(spin , 0., 0., 1.);
glTranslatef(50.0, 50.0, 0);
glTranslatef(-50.0, -50.0, 0);
glBegin(GL_QUADS); // Each set of 4 vertices form a quad
//glColor3ub(redc, greenc, bluec); // Random red green blue value
glColor3f(1.0f, 0.0f, 0.0f); // Random red green blue value
glVertex2f(-0.5f, -0.5f); // x, y default 0.5f values
glVertex2f( 0.5f, -0.5f);
glVertex2f( 0.5f, 0.5f);
glVertex2f(-0.5f, 0.5f);
glEnd();
//angle += 5.0f;
glPopMatrix();
// glFlush(); // Render now
glutSwapBuffers(); // Double buffered - swap the front and back buffers
}
/* Callback handler for special-key event */
void specialKeys(int key, int x, int y) {
switch (key) {
case GLUT_KEY_F1: // F1: Toggle wireframe and solid polygon
prim_polygonmode = !prim_polygonmode; // Toggle state
break;
}
}
/* Main function: GLUT runs as a console application starting at main() */
int main(int argc, char** argv) {
glutInit(&argc, argv); // Initialize GLUT
glutInitDisplayMode(GLUT_DOUBLE); // Enable double buffered mode
glutInitWindowSize(1360, 768); // Set the window's initial width & height
glutInitWindowPosition(0, 0);
// Position the window's initial top-left corner
glutCreateWindow("OpenGL Setup Test"); // Create a window with the given title
glutSpecialFunc(specialKeys); // Register callback handler for special-key event
glutDisplayFunc(display); // Register display callback handler for window re-paint
glutReshapeFunc(reshape);
glutIdleFunc(idle);
// GLuint texture;
texture = LoadTexture( "stars.bmp" );
initGL();
glutMainLoop();// Enter the event-processing loop
//Free our texture
glDeleteTextures( 1, &texture );
return 0;
}
这段代码有一组背景和方形的小动画。 不知道为什么不能设置更多纯色。然后线框正方形我得到了一条非常小的红色线需要得到明亮的颜色 red.Maybe 任何过滤器，你的缓冲区导致了那个？ 如果可能请帮助我。
OpenGL 是一个状态引擎。一旦设置了状态，它就会一直存在，直到再次更改为止。 这意味着如果启用二维纹理，则以下所有几何体都是 "textured".
注意，当调用glVertex2f时，当前纹理坐标与顶点坐标相关联。如果您没有明确设置纹理坐标，那么最后设置的纹理坐标仍然是当前纹理坐标，并且将关联到顶点坐标。这可能会导致类似随机行为。
如果启用纹理，则默认情况下纹理元素的颜色乘以当前颜色，因为默认情况下纹理环境模式 (GL_TEXTURE_ENV_MODE) 为 GL_MODULATE。参见 glTexEnv。
这意味着：
如果您想绘制带有纹理的几何图形，请启用纹理并设置 "white" 颜色：
glEnable(GL_TEXTURE_2D)
glColor3f(1.0f, 1.0f, 1.0f);
background();
如果要绘制颜色统一的几何图形，请设置颜色并禁用纹理：
glDisable(GL_TEXTURE_2D);
glColor3f(1.0f, 0.0f, 0.0f);
glBegin(GL_QUADS);
// [...]
glEnd();