Texture Mapping Beispiel - gdv.informatik.uni-frankfurt.de · Texturen II Universität...

Texture Mapping

Beispiel

Universität Frankfurt

Texture Mapping


Warum?

- Detailreiche Oberfläche ohne zusätzliche Polygone

Texturen I


- 1D-Texturen

- 2D-Texturen

- 3D-Texturen

Element der Textur: Texel

Texturen II


- Änderung der Farben (Farbtexturen)

- Änderung der Normalen (Bump-Mapping)

- Änderung der Helligkeiten

- Änderung der Parameter des Beleuchtungsmodells

Texture Mapping I


Texture Mapping II


OpenGL Texture Mapping I


glEnable(GL_Texture_1D)

glDisable (GL_Texture_1D)


glDisable (GL_Texture_2D)


glDisable(GL_Texture_3D)

OpenGL Texture Mapping II

Laden einer Textur


glTexImage{1,2}D(GLenum target, GLint level, GLint internalformat,

GLsizei width, {GLsizei height},GLint border,

GLenum format, GLenum type, void *data)

target: GL_TEXTURE_1D, GL_TEXTURE_2D, GL_PROXY_TEXTURE_2D

level: Mipmap-Level, 0 bezeichnet das Ausgangsbild, n bezeichnet die n-teMipmap-Reduktionsstufe

internalformat: Anzahl der Farbkomponenten der Textur, entweder 1,2,3,4, oder GL_RGB, GL_RGBA, GL_ALPHA, .......

width: Breite der Textur in Anzahl Texel, Größe: 2n+2(border) texel

{height}: Höhe der Textur in Anzahl Texel, Größe: 2n+2(border) texel

border: Rahmenbreite, 0 oder 1 Texel

format: Pixel-Format: GL_RGB, GL_RGBA, GL_ALPHA, .....

type: GL_UNSIGNED_BYTE, GL_BYTE, GL_SHORT, GL_INT

data: Zeiger auf Pixel-Daten

OpenGL Texture Mapping IIa

Laden einer Textur#define checkImageWidth 64

#define checkImageHeight 64

static GLubyte checkImage[checkImageHeight][checkImageWidth][4];

int i, j, c;

/* Create checkerboard texture */

for (i = 0; i < checkImageHeight; i++) {

for (j = 0; j < checkImageWidth; j++) {

c = ((((i&0x8)==0)^((j&0x8))==0))*255;

checkImage[i][j][0] = (GLubyte) c;



checkImage[i][j][3] = (GLubyte) 255; } }

glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, checkImageWidth,

checkImageHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, checkImage);


OpenGL Texture Mapping IIb

Laden einer Textur

GLbyte *pBytes;

GLint iWidth, iHeight, iComponents, eFormat;

GLenum eFormat;

glPixelStorei(GL_UNPACK_ALIGNMENT, 1);

pBytes = gltLoadTGA("Stone.tga", &iWidth, &iHeight, &iComponents, &eFormat);

glTexImage2D(GL_TEXTURE_2D, 0, iComponents, iWidth, iHeight, 0, eFormat,

GL_UNSIGNED_BYTE, pBytes);

free(pBytes);


OpenGL Texture Mapping III

Texture Environment


glTexEnv{i,f} (GLenum target, GLenum pname, {GLint, GLfloat } param)

glTexEnv{i,f}v (GLenum target, GLenum pname, {GLint, GLfloat } *params)

target: GL_TEXTURE_ENV

pname: GL_TEXTURE_ENV_MODE, GL_TEXTURE_ENV_COLOR

param: GL_MODULATE, GL_DECAL, GL_REPLACE, GL_BLEND, (red, green, blue, alpha)

Beispiele:

glTexEnvi (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE);

GLfloat Color[4] = {1.0, 0.0, 1.0, 0.5);glTexEnvi (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_BLEND);glTexEnvfv (GL_TEXTURE_ENV, GL_TEXTURE_ENV_COLOR, Color);

OpenGL Texture Mapping IV

Texture Parameter


glTexParameter{i,f} (GLenum target, GLenum pname, {GLint, GLfloat } param)

glTexParameter{i,f}v (GLenum target, GLenum pname, {GLint, GLfloat } *params)

target: GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D

pname: GL_TEXTURE_MIN_FILTER, GL_TEXTURE_MAG_FILTER,GL_TEXTURE_WRAP_S, GL_TEXTURE_WRAP_T, ....

param: GL_LINEAR, GL_NEAREST, GL_CLAMP_TO_EDGE, GL_GL_REPEAT,

Beispiele:

glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);

glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);

OpenGL Texture Mapping VI

Textur-Koordinaten


glTexCoord1{d,f,i,s} (GLx s) x∈∈∈∈{double, float, int, short}

glTexCoord2{d,f,i,s} (GLx s, GLy t), x,y∈∈∈∈{double, float, int, short}

glTexCoord1{d,f,i,s}v (const GLx *v) x∈∈∈∈{double, float, int, short}

glTexCoord2{d,f,i,s}v (const GLx *v), x∈∈∈∈{double, float, int, short}

Beispiele:glTexCoord2f(1.0f, 2.0f);glVertex3fv(vCorners[0]);

glTexCoord2f(0.0f, 0.0f);glVertex3fv(vCorners[2]);

glTexCoord2f(2.0f, 0.0f);glVertex3fv(vCorners[1]);

Multiple Textures I


glGenTextures(GLsizei n, GLuint *textures)

n: Anzahl der benötigten Texture-Identifier

textures: Feld, in dem die Texture-Identifier abgelegt werden

glBindTexture(GLenum target, GLuint texture)

target: GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3D

texture: bezeichnet einen der von OpenGL generierten Identifier

glDeleteTextures(GLsizei n, const GLuint *textures)

n: Anzahl der zu löschenden Texturentextures: Feld, in dem die zu löschendenTexture-Identifier abgelegt sind

Multiple Textures II

Beispiel


#define NO_TEXTURES 2#define CHECKER 0#define STONE 1

static GLuint textures[NO_TEXTURES];glGenTextures(NO_TEXTURES, textures);

//Texture CheckerboardglBindTexture(GL_TEXTURE_2D, textures[CHECKER]);

glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, checkImageWidth,checkImageHeight, 0, GL_RGBA, GL_UNSIGNED_BYTE, checkImage);

glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);

//Texture StoneglBindTexture(GL_TEXTURE_2D, textures[STONE]);..................

Globale Beleuchtungsparameter


void glLightModel{i,f}(GLenum pname, TYPE param)

void glLightModel{i,f}v(GLenum pname,TYPE *param)

Parameter-Name Parameter

GL_LIGHT_MODEL_COLOR_CONTROL GL_SINGLE_COLOR

GL_SEPARATE_SPECULAR_COLOR

Globale Beleuchtungsparameter


GL_SINGLE_COLOR GL_SEPARATE_SPECULAR_COLOR

Mipmapping I


Mip: „multum in parvo“

Problem: Szintillation

Mipmapping II


Mipmapping III


glTexParameter{i,f} (GLenum target, GLenum pname, {GLint, GLfloat } param)

glTexParameter{i,f}v (GLenum target, GLenum pname, {GLint, GLfloat } *params)

target: GL_TEXTURE_1D, GL_TEXTURE_2D, GL_TEXTURE_3Dpname: GL_TEXTURE_MIN_FILTER, GL_TEXTURE_MAG_FILTER,

, ....param: ...., GL_NEAREST_MIPMAP_NEAREST, GL_LINEAR_MIPMAP_NEAREST,

GL_NEAREST_MIPMAP_LINEAR, GL_LINEAR_MIPMAP_LINEAR, .....

Beispiel:

glTexParameteri (GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR_MIPMAP_LINEAR);

How to Generate a Mipmap I


1.) Do it by hand/program

How to Generate a Mipmap II


1.) Do it by hand/program

GLubyte mipmapImage32[32][32][4];






glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, 32, 32, 0, GL_RGBA, GL_UNSIGNED_BYTE,

mipmapImage32);


mipmapImage16);


mipmapImage8);


mipmapImage4);


mipmapImage2);


mipmapImage1);

How to Generate a Mipmap III


2.) Let OpenGL do it!

GLint gluBuild2DMipmaps (GLenum target, GLint internalFormat,

GLsizei width, GLsizei height, GLenum format,

GLenum type, void *data)

target: GL_TEXTURE_2DinternalFormat: Anzahl der Farbkomponenten der Textur, entweder 1,2,3,4,

oder GL_RGB, GL_RGBA, GL_ALPHA, .......width: Breite der Textur in Anzahl Texelheight: Höhe der Textur in Anzahl Texelformat: Pixel-Format: GL_RGB, GL_RGBA, GL_ALPHA, .....type: GL_UNSIGNED_BYTE, GL_BYTE, GL_SHORT, GL_INTdata: Zeiger auf Pixel-Daten

Beispiel: gluBuild2DMipmaps(GL_TEXTURE_2D, GL_RGBA, 32, 32,GL_RGBA, GL_UNSIGNED_BYTE, checkImage);

Automatic Texture Coordinate Generation I

Contour Lines & Environment Mapping


Automatic Texture Coordinate Generation II

Contour Lines


glEnable(GL_TEXTURE_GEN_{S, T, ...});

glTexGen{ifd} (GLenum coord, GLenum pname, TYPE param)

glTexGen{ifd}v (GLenum coord, GLenum pname, TYPE *param)

coord: GL_S, GL_T, ...

pname: TEXTURE_GEN_MODE, GL_OBJECT_PLANE, GL_EYE_PLANE

param: GL_OBJECT_LINEAR, GL_EYE_LINEAR, GL_SPHERE_MAP

Beispiele:glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);

glTexGenfv(GL_S, GL_OBJECT_PLANE, *plane);

Automatic Texture Coordinate Generation III

Contour Lines Defined in Eye Coordinate System


Ebene: (nx, ny, nz, d)

Abstand eines Punktes (x, y, z, w) von der Ebene bestimmt die Texturkoordinate:

{s,t}= nx*x +ny*y+nz*z+d*w

Beispiel:

xequalzero = {1.0, 0.0, 0.0, 0.0};

glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_OBJECT_LINEAR);

glTexGenfv(GL_S, GL_OBJECT_PLANE, xequalzero);

Automatic Texture Coordinate Generation IV

Contour Lines


Automatic Texture Coordinate Generation V

Contour Lines Defined in Object Coordinate System


Ebene: (n‘x, n‘y, nz, d)= (nx, ny, nz, d)M-1, mit M Model View Matrix

Abstand eines Punktes (x, y, z, w) von der Ebene bestimmt die Texturkoordinate:

{s,t}= n‘x*x +n‘y*y+n‘z*z+d‘*w

Beispiel: xequalzero = {1.0, 0.0, 0.0, 0.0};

glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR);

glTexGenfv(GL_S, GL_EYE_PLANE, xequalzero);

Automatic Texture Coordinate Generation VI

Reflective Ray


Automatic Texture Coordinate Generation VII

Sphere Mapping


Automatic Texture Coordinate Generation VIII

Sphere Mapping - Texture


Automatic Texture Coordinate Generation IX

The Mathematics of Sphere Mapping

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Automatic Texture Coordinate Generation IX

Sphere Mapping


//Turn on texture coordinate generationglEnable(GL_TEXTURE_GEN_S);glEnable(GL_TEXTURE_GEN_T);

// Sphere MapglTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP);glTexGeni(GL_T, GL_TEXTURE_GEN_MODE, GL_SPHERE_MAP);

Texture Mapping Beispiel - gdv.informatik.uni-frankfurt.de · Texturen II Universität...

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