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CH6 Texture
CH6 Texture
Before coding… 1/2
Prepare all texture images you need. BMP file is a good choice If you want to use TIFF file, maybe try
this. http://gnuwin32.sourceforge.net/packages/tiff
.htm Download the developer files. Or…just change TIFF files to BMP files ˋ(′ ～‵ ")ˊ
Before coding… 2/2
Add GlAux.Lib into your project.
Example Program 1/4
#include<gl/glaux.h>#include<gl/glut.h>#define TEX_NUM 1 //the number of textures
you use.
#define MIPMAP
AUX_RGBImageRec * img; //to save image file
GLuint texObject[TEX_NUM];//texture object
Example Program 2/4
void LoadTexture(char* filename){img = auxDIBImageLoad(filename);glGenTextures(TEX_NUM, texObject);glBindTexture(GL_TEXTURE_2D, texObject[0]);
#ifdef MIPMAPgluBuild2DMipmaps(GL_TEXTURE_2D, 4, img->sizeX, img->sizeY, GL_RGB,
GL_UNSIGNED_BYTE, img->data);glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR_MIPMAP_LINEAR);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);
#elseglTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, img->sizeX, img->sizeY, 0, GL_RGB, GL_UNSIGNED_BYTE, img->data);glTexEnvf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
#endifglHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
}
Example Program 3/4
void GL_display(){glClear(GL_COLOR_BUFFER_BIT);glColor3f(1.0, 1.0, 1.0);glEnable(GL_TEXTURE_2D);glBindTexture(GL_TEXTURE_2D, texObject[0]);glBegin(GL_QUADS);glTexCoord2f(0.0, 0.0);glVertex3f(-50.0, 0.0, 0.0);glTexCoord2f(0.0, 100.0);glVertex3f(-50.0, 0.0, 100.0);glTexCoord2f(100.0, 100.0);glVertex3f(50.0, 0.0, 100.0);glTexCoord2f(100.0, 0.0);glVertex3f(50.0, 0.0, 0.0);glEnd();glFlush();
}
Example Program 4/4
void GL_reshape(GLsizei w, GLsizei h){
glViewport(0, 0, w, h);glMatrixMode(GL_PROJECTION);glLoadIdentity();gluPerspective(60.0, (GLfloat)w/(GLfloat)h, 0.5, 100.0);glMatrixMode(GL_MODELVIEW);glLoadIdentity();gluLookAt(0.0, 0.5, 0.0, 50.0, 0.0, 50.0, 0.0, 1.0, 0.0);
}
int main(int argc, char** argv){
glutInit(&argc, argv);glutInitWindowSize(400, 400);glutInitWindowPosition(0, 0);glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA | GLUT_DEPTH);glutCreateWindow("Texture");LoadTexture("check.bmp");glutDisplayFunc(GL_display);glutReshapeFunc(GL_reshape);glutMainLoop();
}
Check.bmp
Width/Height: 256/256
Load BMP file AUX_RGBImageRec* auxDIBImageLoad(char
*); Load a BMP file.
typedef struct _AUX_RGBImageRec { GLint sizeX, sizeY;
unsigned char *data;};
sizeX, sizeY : image width / height. data : A pointer to the image data in memory.
Texture Object void glGenTextures( GLsizei n, GLuint
*textures ); To generate texture names. http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/
glfunc02_3p6b.asp n: the number of texture names to be generated. textures: pointer to the first element of an array in
which the texture are stored. GLboolean glIsTexture( GLuint texture );
To determine if a name corresponds to a texture. http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/
glfunc03_7cv9.asp
Bind texture void glBindTexture( GLenum target, GLuint
texture );
To bind the texture to the target. http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/glfunc01_3bad.asp
target: GL_TEXTURE_1D, GL_TEXTURE_2D
void glDeleteTextures( GLsizei n, const GLuint
*textures ); Delete named textures. http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/glfunc01_6vqr.asp
Specifies 2D texture image 1/4 void glTexImage2D(
GLenum target, GLint level, GLint internalformat, GLsizei width, GLsizei height, GLint border, GLenum format, GLenum type, const GLvoid *pixels
);
Specifies 2D texture image 2/4
Specifies a 2D texture image http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/
glfunc03_16jo.asp
target: Must be GL_TEXTURE_2D level: level-of-detail level. It must be 0 if you
don’t want to use mip-map. internalformat: GL_RGBA and many
others… Width / height : image witdh / height
Specifies 2D texture image 3/4
border: 0 or 1 0 : no border, image width & height must
be power of 2. 1 : use border, image width & height
must be power of 2 plus 2.
Specifies 2D texture image 4/4
format: format of the image data GL_RGB, GL_RGBA, and many others…
type: data type of the image data pixel: A pointer to the image data in
memory. (Hint: the BMP file you have loaded…)
Apply texture to objects 1/3
void glTexEnv{fi}(GLenum target, GLenum pname, GLfloat param ); to indicate how the texels are combined
with the original pixels http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/glfunc03_6xyu.asp
target: must be GL_TEXTURE_ENV pname: must be GL_TEXTURE_ENV_MODE param: 5 choices, see next page
Apply texture to objects 2/3
Base Internal Format GL_REPLACE GL_MODULATE GL_ADD
GL_ALPHA C = Cf, A = At C = Cf, A = AfAt C=Cf, A=AfAtGL_LUMINANCE C = Lt, A = Af C = CfLt, A = Af C=Cf+CT, A=AfGL_LUMINANCE_ALPHA C = Lt, A = At C = CfLt, A = AfAt C=Cf+Ct, A=AfAtGL_INTENSITY C = It, A = It C = CfIt, A = AfItC=Cf+Ct, A=Af+AtGL_RGB C = Ct, A = Af C = CfCt, A = Af C=Cf+Ct, A=AfGL_RGBA C = Ct, A = At C = CfCt, A = AfAt C=Cf+Ct, A=AfAt
Base Internal Format GL_DECAL GL_BLEND
GL_ALPHA Undefined C = Cf, A = AfAtGL_LUMINANCE Undefined C = Cf(1-Lt)+CcLt, A = AfGL_LUMINANCE_ALPHA Undefined C = Cf(1-Lt)+CcLt, A = AfAtGL_INTENSITY Undefined C = Cf(1-It)+CcIt, A = Af(1-It)+AcItGL_RGB C = Ct, A = Af C = Cf(1-Ct)+CcCt, A = AfGL_RGBA C = Cf(1-At)+CtAt, A = At C = Cf(1-Ct)+CcCt, A = AfAt Xc indicates the values assigned with
GL_TEXTURE_ENV_COLOR. * GL_TEXTURE_ENV_COLOR is defined by glGetTexEnvfvXt is the values form texture, Xf is the values in the color buffers.C is the final output color value and A is the output alpha value.
Apply texture to objects 3/3
glTexEnv{fi}v(GLenum target, GLenum pname, const GLfloat *params ) target: must be GL_TEXTURE_ENV pname: GL_TEXTURE_ENV_COLOR or
GL_TEXTURE_ENV_MODE params:
if pname is GL_TEXTURE_ENV_MODE : A pointer to an array of parameters.(GL_MODULATE, GL_DECAL, and GL_BLEND)
if pname is GL_TEXTURE_ENV_COLOR: a pointer to an array of R, G, B, A
Texture parameter 1/5
glTexParameter{if}(GLenum target, GLenum pname, GLfloat param ) Set texture parameters. http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/
glfunc03_9upe.asp
target: GL_TEXTURE_1D, GL_TEXTURE_2D
pname / param: see next page
Texture parameter 2/5
pname param
GL_TEXTURE_WARP_SGL_TEXTURE_WARP_T GL_REPEAT, GL_CLAMP
GL_TEXTURE_MAG_FILTERGL_TEXTURE_MIN_FILTER GL_NEAREST, GL_LINEAR,
GL_NEAREST_MIPMAP_NEAREST,
GL_NEAREST_MIPMAP_LINEAR,GL_LINEAR_MIPMAP_LINEAR,GL_LINEAR_MIPMAP_NEAREST
GL_TEXTURE_BORDER_COLOR color value
Texture parameter 3/5
WARP
Repeat both S, T
Clamp both S, T
Repeat T but Clamp S
Texture parameter 4/5
MAG filter When the pixel being textured maps to an
area less than or equal to one texture element
MIN filter When the pixel being textured maps to an
area greater then one texture element
Texture parameter 5/5
GL_NEARST
pixel
texel
GL_LINEAR
Get average color...
GL_NEAREST_MIPMAP_XXXXXX Find the most closely match mipmap
GL_LINEAR_MIPMAP_XXXXXXX Find the most 2 closely match mipmap and get average.
Build mip-maps 1/3
int gluBuild2DMipmaps( GLenum target, GLint components, GLint width, GLint height, GLenum format, GLenum type, const void *data );
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/glufnc01_406r.asp
Build mip-maps 2/3
target : Must be GL_TEXTURE_2D. components :The number of color
components in the texture. Must be 1, 2, 3, or 4.
width, height :width / height of image. format : GL_RGB, GL_RGBA and many
others… type :The data type for data data :A pointer to the image data in
memory.
Build mip-maps 3/3
without mip-map with mip-map
How to use texture? Remember to enable…
glEnable(GL_TEXTURE_2D); Remember to bind…
glBindTexture(GL_TEXTURE_2D, textName);
Remember to assign texel for each vertex… glTexCoord2f(0.0, 0.0);
glVertex3f(-50.0, 0.0, 0.0);
Review display function void GL_display(){
glClear(GL_COLOR_BUFFER_BIT);glColor3f(1.0, 1.0, 1.0);glEnable(GL_TEXTURE_2D);glBindTexture(GL_TEXTURE_2D, texObject[0]);glBegin(GL_QUADS);glTexCoord2f(0.0, 0.0);glVertex3f(-50.0, 0.0, 0.0);glTexCoord2f(0.0, 100.0);glVertex3f(-50.0, 0.0, 100.0);glTexCoord2f(100.0, 100.0);glVertex3f(50.0, 0.0, 100.0);glTexCoord2f(100.0, 0.0);glVertex3f(50.0, 0.0, 0.0);glEnd();glFlush();
}
Example Program 2 1/3
#include<gl/glaux.h>#include<gl/glut.h>
AUX_RGBImageRec * img;GLuint texObject;
void LoadTexture(char* filename){img = auxDIBImageLoad(filename);glGenTextures(1, &texObject);glBindTexture(GL_TEXTURE_2D, texObject);gluBuild2DMipmaps(GL_TEXTURE_2D, 3, img->sizeX, img->sizeY, GL_RGB, GL_UNSIGNED_BYTE, img->data);glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP); glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP); glEnable(GL_TEXTURE_GEN_S);glEnable(GL_TEXTURE_GEN_T);glEnable(GL_TEXTURE_2D);
}
Example Program 2 2/3
void GL_display(){glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);glEnable(GL_DEPTH_TEST);glColor3f(1.0, 1.0, 1.0);glutSolidTeapot(18);glFlush();
}
void GL_reshape(GLsizei w, GLsizei h){
glViewport(0, 0, w, h);glMatrixMode(GL_PROJECTION);glLoadIdentity();gluPerspective(60.0, (GLfloat)w/(GLfloat)h, 0.5, 100.0);glMatrixMode(GL_MODELVIEW);glLoadIdentity();gluLookAt(0.0, 0.0, 50.0, 0.0, 0.0, 0.0, 0.0, 1.0, 0.0);
}
Example Program 2 3/3
int main(int argc, char** argv){
glutInit(&argc, argv);glutInitWindowSize(400, 400);glutInitWindowPosition(0, 0);glutInitDisplayMode(GLUT_SINGLE | GLUT_RGBA | GLUT_DEPTH);glutCreateWindow("Texture");LoadTexture("environment.bmp");glutDisplayFunc(GL_display);glutReshapeFunc(GL_reshape);glutMainLoop();
}
environment.bmp
Width/Height: 128/128
Automatic Texture-Coordinate Generation 1/4
glTexGen{dfi}(GLenum coord, GLenum pname, GLdouble param); control the generation of texture
coordinates http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/glfunc03_73u6.asp
coord: GL_S, GL_T, GL_R, or GL_Q. pname: must be GL_TEXTURE_GEN_MODE. param: GL_OBJECT_LINEAR,
GL_EYE_LINEAR, or GL_SPHERE_MAP
Automatic Texture-Coordinate Generation 2/4
glTexGen{dfi}v(GLenum coord, GLenum pname, const GLdouble *params ); coord: GL_S, GL_T, GL_R, or GL_Q. pname: GL_TEXTURE_GEN_MODE,
GL_OBJECT_PLANE, or GL_EYE_PLANE params: the array of texture generation
parameters, if pname is GL_OBJECT_PLANE, or GL_EYE_PLANE.
*Generated plane = p1X + p2Y + p3Z + p4W
Automatic Texture-Coordinate Generation 3/4
void LoadTexture(char* filename){GLint par[] = {1, 1, 1, 0};img = auxDIBImageLoad(filename);glGenTextures(1, &texObject);glBindTexture(GL_TEXTURE_2D, texObject);gluBuild2DMipmaps(GL_TEXTURE_2D, 3, img->sizeX, img->sizeY, GL_RGB, GL_UNSIGNED_BYTE, img->data);glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR); glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR); glTexGeniv(GL_S, GL_OBJECT_PLANE, par);glTexGeniv(GL_T, GL_OBJECT_PLANE, par);glEnable(GL_TEXTURE_GEN_S);glEnable(GL_TEXTURE_GEN_T);glEnable(GL_TEXTURE_2D);
}
Automatic Texture-Coordinate Generation 4/4
If change parameters… par[] = {1, 0, 0, 0}
par[] = {0, 1, 0, 0}
Environment map…(review)void LoadTexture(char* filename){
img = auxDIBImageLoad(filename);glGenTextures(1, &texObject);glBindTexture(GL_TEXTURE_2D, texObject);gluBuild2DMipmaps(GL_TEXTURE_2D, 3, img->sizeX,
img->sizeY, GL_RGB, GL_UNSIGNED_BYTE, img->data);glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP); glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP); glEnable(GL_TEXTURE_GEN_S);glEnable(GL_TEXTURE_GEN_T);glEnable(GL_TEXTURE_2D);
}
So easy…v( ￣︶￣ )y
