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Skybox on OpenGL

I am working on an environment map for skybox in OpenGL and have encountered a texture problem. My code creates texture tiles that I'm trying to match, and not just one large texture. The tiles also lost most of their resolution and are very small.

Here is my code:

#include <windows.h> #include <stdio.h> #include <glew.h> #include <glut.h> #include "Camera.h" Camera cam; GLuint texture [6]; //the array for our texture GLfloat angle = 0.0; GLuint LoadTexture( const char * filename, int width, int height) { GLuint texture; unsigned char * data; FILE* file; file = fopen( filename, "rb" ); if ( file == NULL ) return 0; data = (unsigned char *)malloc( width * height * 3 ); fread( data, width * height * 3, 1, file ); fclose( file ); glGenTextures( 1, &texture ); glBindTexture( GL_TEXTURE_2D, texture ); glTexEnvf( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR ); glTexParameterf( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_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; } void FreeTexture( GLuint texture ) { glDeleteTextures( 1, &texture ); } void skybox (void) { float x = 0; float y = 0; float z = 0; float width = 100; float height = 100; float length = 100; // Bind the BACK texture of the sky map to the BACK side of the cube glBindTexture(GL_TEXTURE_2D, texture[0]); // Center the skybox x = x - width / 2; y = y - height / 2; z = z - length / 2; glBegin(GL_QUADS); glTexCoord2f(1.0f, 0.0f); glVertex3f(x + width, y, z); glTexCoord2f(1.0f, 1.0f); glVertex3f(x + width, y + height, z); glTexCoord2f(0.0f, 1.0f); glVertex3f(x, y + height, z); glTexCoord2f(0.0f, 0.0f); glVertex3f(x, y, z); glEnd(); glBindTexture(GL_TEXTURE_2D, texture[1]); glBegin(GL_QUADS); glTexCoord2f(1.0f, 0.0f); glVertex3f(x, y, z + length); glTexCoord2f(1.0f, 1.0f); glVertex3f(x, y + height, z + length); glTexCoord2f(0.0f, 1.0f); glVertex3f(x + width, y + height, z + length); glTexCoord2f(0.0f, 0.0f); glVertex3f(x + width, y, z + length); glEnd(); glBindTexture(GL_TEXTURE_2D, texture[4]); glBegin(GL_QUADS); glTexCoord2f(1.0f, 0.0f); glVertex3f(x, y, z); glTexCoord2f(1.0f, 1.0f); glVertex3f(x, y, z + length); glTexCoord2f(0.0f, 1.0f); glVertex3f(x + width, y, z + length); glTexCoord2f(0.0f, 0.0f); glVertex3f(x + width, y, z); glEnd(); glBindTexture(GL_TEXTURE_2D, texture[5]); glBegin(GL_QUADS); glTexCoord2f(0.0f, 0.0f); glVertex3f(x + width, y + height, z); glTexCoord2f(1.0f, 0.0f); glVertex3f(x + width, y + height, z + length); glTexCoord2f(1.0f, 1.0f); glVertex3f(x, y + height, z + length); glTexCoord2f(0.0f, 1.0f); glVertex3f(x, y + height, z); glEnd(); glBindTexture(GL_TEXTURE_2D, texture[2]); glBegin(GL_QUADS); glTexCoord2f(1.0f, 1.0f); glVertex3f(x, y + height, z); glTexCoord2f(0.0f, 1.0f); glVertex3f(x, y + height, z + length); glTexCoord2f(0.0f, 0.0f); glVertex3f(x, y, z + length); glTexCoord2f(1.0f, 0.0f); glVertex3f(x, y, z); glEnd(); glBindTexture(GL_TEXTURE_2D, texture[3]); glBegin(GL_QUADS); glTexCoord2f(0.0f, 0.0f); glVertex3f(x + width, y, z); glTexCoord2f(1.0f, 0.0f); glVertex3f(x + width, y, z + length); glTexCoord2f(1.0f, 1.0f); glVertex3f(x + width, y + height, z + length); glTexCoord2f(0.0f, 1.0f); glVertex3f(x + width, y + height, z); glEnd(); //glBindTexture( GL_TEXTURE_CUBE_MAP, texture[0] ); //bind the texture //glRotatef( angle, 1.0f, 1.0f, 1.0f ); //glutSolidSphere(2, 40, 40); } void display (void) { glClearColor (0.0,0.0,0.0,1.0); glClear (GL_COLOR_BUFFER_BIT); glLoadIdentity(); cam.camera(); //gluLookAt (20.0, 20.0, 20.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0); texture[0] = LoadTexture( "Back.bmp", 256, 256 ); //load the texture texture[1] = LoadTexture( "Front.bmp", 256, 256 ); //load the texture texture[2] = LoadTexture( "Left.bmp", 256, 256 ); //load the texture texture[3] = LoadTexture( "Right.bmp", 256, 256 ); //load the texture texture[4] = LoadTexture( "Bottom.bmp", 256, 256 ); //load the texture texture[5] = LoadTexture( "Top.bmp", 256, 256 ); //load the texture glEnable(GL_TEXTURE_2D); //enable 2D texturing glEnable(GL_TEXTURE_GEN_S); //enable texture coordinate generation glEnable(GL_TEXTURE_GEN_T); skybox(); for (int i = 0; i < 6; i++) { FreeTexture( texture[i] ); } glutSwapBuffers(); angle = angle + 0.5; cam.incAngle(); } void keyboard (unsigned char key, int x, int y) { switch (key) { case 'q': cam.lookUpwards(); break; case 'z': cam.lookDownwards(); break; case 'w': cam.slideForward(); break; case 's': cam.slideBackward(); break; case 'a': cam.strafeLeft(); break; case 'd': cam.strafeRight(); break; case 'e': exit(0); break; default: break; } } void reshape(int x, int y) { cam.reshape(x, y); } void mouseMovement(int x, int y) { cam.mouseMovement(x, y); } int main (int argc, char **argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_DOUBLE); glutInitWindowSize(500, 500); glutInitWindowPosition(100, 100); glutCreateWindow("A basic OpenGL Window"); glutDisplayFunc(display); glutIdleFunc(display); glutReshapeFunc(reshape); glutKeyboardFunc(keyboard); glutPassiveMotionFunc(mouseMovement); glutMainLoop(); }
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2 answers

Since you specify the texture coordinates manually, you must remove / disable the following automatic creation:

 glEnable(GL_TEXTURE_GEN_S); //enable texture coordinate generation glEnable(GL_TEXTURE_GEN_T);

It is also suspicious that you are loading .bmp files as raw RGB data only.

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The color will return to normal if we replace GL_RGB with GL_BGR, which is included in "glew.h"

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Source: https://habr.com/ru/post/1447399/

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