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