9 1 checker c include GLglut h include

예제 9 -1 텍스처 맵이 적용된 체크판: checker. c #include <GL/glut. h> #include <stdlib. h> #include <stdio. h> /* Create checkerboard texture */ #define check. Image. Width 64 #define check. Image. Height 64 static GLubyte check. Image[check. Image. Height][check. Image. Width][4]; #ifdef GL_VERSION_1_1 static GLuint tex. Name; #endif 2010 -2학기 가상현실 8

void make. Check. Image(void) { int i, j, c; for (i = 0; i < check. Image. Height; i++) { for (j = 0; j < check. Image. Width; j++) { c = ((((i&0 x 8)==0)^((j&0 x 8))==0))*255; check. Image[i][j][0] = (GLubyte) c; check. Image[i][j][1] = (GLubyte) c; check. Image[i][j][2] = (GLubyte) c; check. Image[i][j][3] = (GLubyte) 255; } } } 2010 -2학기 가상현실 9

void init(void) { gl. Clear. Color (0. 0, 0. 0); gl. Shade. Model(GL_FLAT); gl. Enable(GL_DEPTH_TEST); make. Check. Image(); gl. Pixel. Storei(GL_UNPACK_ALIGNMENT, 1); #ifdef GL_VERSION_1_1 gl. Gen. Textures(1, &tex. Name); gl. Bind. Texture(GL_TEXTURE_2 D, tex. Name); #endif 2010 -2학기 가상현실 10

gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_WRAP_S, GL_REPEAT); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_WRAP_T, GL_REPEAT); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); #ifdef GL_VERSION_1_1 gl. Tex. Image 2 D(GL_TEXTURE_2 D, 0, GL_RGBA, check. Image. Width, check. Image. Height, 0, GL_RGBA, GL_UNSIGNED_BYTE, check. Image); #else gl. Tex. Image 2 D(GL_TEXTURE_2 D, 0, 4, check. Image. Width, check. Image. Height, 0, GL_RGBA, GL_UNSIGNED_BYTE, check. Image); #endif } 2010 -2학기 가상현실 11

void display(void) { gl. Clear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); gl. Enable(GL_TEXTURE_2 D); gl. Tex. Envf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); #ifdef GL_VERSION_1_1 gl. Bind. Texture(GL_TEXTURE_2 D, tex. Name); #endif gl. Begin(GL_QUADS); gl. Tex. Coord 2 f(0. 0, 0. 0); gl. Tex. Coord 2 f(0. 0, 1. 0); gl. Tex. Coord 2 f(1. 0, 0. 0); 2010 -2학기 gl. Vertex 3 f(-2. 0, -1. 0, 0. 0); gl. Vertex 3 f(-2. 0, 1. 0, 0. 0); gl. Vertex 3 f(0. 0, -1. 0, 0. 0); 가상현실 12

gl. Tex. Coord 2 f(0. 0, 0. 0); gl. Vertex 3 f(1. 0, -1. 0, 0. 0); gl. Tex. Coord 2 f(0. 0, 1. 0); gl. Vertex 3 f(1. 0, 0. 0); gl. Tex. Coord 2 f(1. 0, 1. 0); gl. Vertex 3 f(2. 41421, 1. 0, -1. 41421); gl. Tex. Coord 2 f(1. 0, 0. 0); gl. Vertex 3 f(2. 41421, -1. 0, -1. 41421); gl. End(); gl. Flush(); gl. Disable(GL_TEXTURE_2 D); } void reshape(int w, int h) { gl. Viewport(0, 0, (GLsizei) w, (GLsizei) h); gl. Matrix. Mode(GL_PROJECTION); gl. Load. Identity(); 2010 -2학기 가상현실 13

glu. Perspective(60. 0, (GLfloat) w/(GLfloat) h, 1. 0, 30. 0); gl. Matrix. Mode(GL_MODELVIEW); gl. Load. Identity(); gl. Translatef(0. 0, -3. 6); } void keyboard (unsigned char key, int x, int y) { switch (key) { case 27: exit(0); break; default: break; } } 2010 -2학기 가상현실 14

int main(int argc, char** argv) { glut. Init(&argc, argv); glut. Init. Display. Mode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH); glut. Init. Window. Size(250, 250); glut. Init. Window. Position(100, 100); glut. Create. Window(argv[0]); init(); glut. Display. Func(display); glut. Reshape. Func(reshape); glut. Keyboard. Func(keyboard); glut. Main. Loop(); return 0; } 2010 -2학기 가상현실 15

예제 9 -2 텍스처 프록시로 텍스처 리소스 요청하기 GLInt width; gl. Tex. Image 2 D(GL_PROXY_TEXTURE_2 D, 0, GL_RGBA 8, 64, 0, GL_RGBA, GL_UNSIGNED_BYTE, NULL); gl. Get. Tex. Level. Parameteriv(GL_PROXY_TEXTURE_2 D, 0, GL_TEXTURE_WIDTH, &width); 2010 -2학기 가상현실 23

예제 9 -3 텍스처 서브 이미지 교체: texsub. c #include <GL/glut. h> #include <stdlib. h> #include <stdio. h> #ifdef GL_VERSION_1_1 #define check. Image. Width 64 #define check. Image. Height 64 #define sub. Image. Width 16 #define sub. Image. Height 16 static GLubyte check. Image[check. Image. Height][check. Image. Width][4]; static GLubyte sub. Image[sub. Image. Height][sub. Image. Width][4]; static GLuint tex. Name; 2010 -2학기 가상현실 25

void make. Check. Images(void) { int i, j, c; for (i = 0; i < check. Image. Height; i++) { for (j = 0; j < check. Image. Width; j++) { c = (((i&0 x 8)==0)^((j&0 x 8)==0))*255; //정정 check. Image[i][j][0] = (GLubyte) c; check. Image[i][j][1] = (GLubyte) c; check. Image[i][j][2] = (GLubyte) c; check. Image[i][j][3] = (GLubyte) 255; } } 2010 -2학기 가상현실 26

for (i = 0; i < sub. Image. Height; i++) { for (j = 0; j < sub. Image. Width; j++) { c = (((i&0 x 4)==0)^((j&0 x 4)==0))*255; //정정 sub. Image[i][j][0] = (GLubyte) c; sub. Image[i][j][1] = (GLubyte) 0; sub. Image[i][j][2] = (GLubyte) 0; sub. Image[i][j][3] = (GLubyte) 255; } }} void init(void) { gl. Clear. Color (0. 0, 0. 0); gl. Shade. Model(GL_FLAT); gl. Enable(GL_DEPTH_TEST); 2010 -2학기 가상현실 27

make. Check. Images(); gl. Pixel. Storei(GL_UNPACK_ALIGNMENT, 1); gl. Gen. Textures(1, &tex. Name); gl. Bind. Texture(GL_TEXTURE_2 D, tex. Name); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_WRAP_S, GL_REPEAT); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_WRAP_T, GL_REPEAT); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); gl. Tex. Image 2 D(GL_TEXTURE_2 D, 0, GL_RGBA, check. Image. Width, check. Image. Height, 0, GL_RGBA, GL_UNSIGNED_BYTE, check. Image); } 2010 -2학기 가상현실 28

void display(void) { gl. Clear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); gl. Enable(GL_TEXTURE_2 D); gl. Tex. Envf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); gl. Bind. Texture(GL_TEXTURE_2 D, tex. Name); gl. Begin(GL_QUADS); gl. Tex. Coord 2 f(0. 0, 0. 0); gl. Vertex 3 f(-2. 0, -1. 0, 0. 0); gl. Tex. Coord 2 f(0. 0, 1. 0); gl. Vertex 3 f(-2. 0, 1. 0, 0. 0); gl. Tex. Coord 2 f(1. 0, 1. 0); gl. Vertex 3 f(0. 0, 1. 0, 0. 0); gl. Tex. Coord 2 f(1. 0, 0. 0); gl. Vertex 3 f(0. 0, -1. 0, 0. 0); 2010 -2학기 가상현실 29

gl. Tex. Coord 2 f(0. 0, 0. 0); gl. Vertex 3 f(1. 0, -1. 0, 0. 0); gl. Tex. Coord 2 f(0. 0, 1. 0); gl. Vertex 3 f(1. 0, 0. 0); gl. Tex. Coord 2 f(1. 0, 1. 0); gl. Vertex 3 f(2. 41421, 1. 0, -1. 41421); gl. Tex. Coord 2 f(1. 0, 0. 0); gl. Vertex 3 f(2. 41421, -1. 0, -1. 41421); gl. End(); gl. Flush(); gl. Disable(GL_TEXTURE_2 D); } void reshape(int w, int h) { gl. Viewport(0, 0, (GLsizei) w, (GLsizei) h); gl. Matrix. Mode(GL_PROJECTION); gl. Load. Identity(); 2010 -2학기 가상현실 30

glu. Perspective(60. 0, (GLfloat) w/(GLfloat) h, 1. 0, 30. 0); gl. Matrix. Mode(GL_MODELVIEW); gl. Load. Identity(); gl. Translatef(0. 0, -3. 6); } void keyboard (unsigned char key, int x, int y){ switch (key) { case 's': case 'S': gl. Bind. Texture(GL_TEXTURE_2 D, tex. Name); gl. Tex. Sub. Image 2 D(GL_TEXTURE_2 D, 0, 12, 44, sub. Image. Width, sub. Image. Height, GL_RGBA, GL_UNSIGNED_BYTE, sub. Image); glut. Post. Redisplay(); break; 2010 -2학기 가상현실 31

case 'r': case 'R': gl. Bind. Texture(GL_TEXTURE_2 D, tex. Name); gl. Tex. Image 2 D(GL_TEXTURE_2 D, 0, GL_RGBA, check. Image. Width, check. Image. Height, 0, GL_RGBA, GL_UNSIGNED_BYTE, check. Image); glut. Post. Redisplay(); break; case 27: exit(0); break; default: break; } } 2010 -2학기 가상현실 32

int main(int argc, char** argv) { glut. Init(&argc, argv); glut. Init. Display. Mode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH); glut. Init. Window. Size(250, 250); glut. Init. Window. Position(100, 100); glut. Create. Window(argv[0]); init(); glut. Display. Func(display); glut. Reshape. Func(reshape); glut. Keyboard. Func(keyboard); glut. Main. Loop(); return 0; } 2010 -2학기 가상현실 33

#else int main(int argc, char** argv) { fprintf (stderr, "This program demonstrates a feature which is not in Open. GL Version 1. 0. n"); fprintf (stderr, "If your implementation of Open. GL Version 1. 0 has the right extensions, n"); fprintf (stderr, "you may be able to modify this program to make it run. n"); return 0; } #endif 2010 -2학기 가상현실 34

void gl. Tex. Image 3 D(GLenum target, GLint level, GLint internal. Format, GLsizei width, GLsizei height, GLsizei depth, GLint border, GLenum format, GLenum type, const GLvoid *texels) l l l 3차원 텍스처 정의 모든 변수는 gl. Tex. Image 2 D() 와 같은 의미로 사용되나 텍셀은 3 차원 배열이고 depth 변수가 추가. Depth 값은 2 m(테두리가 있 을 경우엔 2 m+1) 사용자는 밉맵과 프록시를 공급할 수 있으며, 동일한 필터링 옵 션이 가능 2010 -2학기 가상현실 42

3차원 텍스처의 전체 또는 부분을 대체하려면 gl. Tex. Sub. Image 3 D() 를 사용 void gl. Tex. Sub. Image 3 D(GLenum target, GLint level, GLint xoffset, GLint yoffset, GLint zoffset, GLsizei width, GLsizei height, GLsizei depth, GLenum format, GLenum type, const GLvoid *texels); l l l 현존하는 3차원 텍스처 이미지를 대체하는 3차원 텍스처 배열을 정의 target 변수는 GL_TEXTURE_3 D로 해야 함 level, format, type : gl. Tex. Image 3 D() 에서 사용된 것과 같다. 2010 -2학기 가상현실 43

*IMAGE_HEIGHT 픽셀 저장 모드 Subimage In layer 1 *ROW_LENGTH Subimage Height *SKIP_PIXELS In layer 0 *SKIP_ROWS *IMAGE_ HEIGHT layer 1 layer 0 2010 -2학기 가상현실 47

예제 9 -5 밉맵 텍스처: mipmap. c #include <GL/glut. h> #include <stdlib. h> GLubyte GLubyte mipmap. Image 32[32][4]; mipmap. Image 16[16][4]; mipmap. Image 8[8][8][4]; mipmap. Image 4[4][4][4]; mipmap. Image 2[2][2][4]; mipmap. Image 1[1][1][4]; #ifdef GL_VERSION_1_1 static GLuint tex. Name; #endif 2010 -2학기 가상현실 49

void make. Images(void) { int i, j; for (i = 0; i < 32; i++) { for (j = 0; j < 32; j++) { mipmap. Image 32[i][j][0] mipmap. Image 32[i][j][1] mipmap. Image 32[i][j][2] mipmap. Image 32[i][j][3] } } 2010 -2학기 = = 255; 0; 255; 가상현실 50

for (i = 0; i < 16; i++) { for (j = 0; j < 16; j++) { mipmap. Image 16[i][j][0] = 255; mipmap. Image 16[i][j][1] = 0; mipmap. Image 16[i][j][2] = 255; mipmap. Image 16[i][j][3] = 255; } for (i = 0; i < 8; i++) { for (j = 0; j < 8; j++) { mipmap. Image 8[i][j][0] = 255; mipmap. Image 8[i][j][1] = 0; mipmap. Image 8[i][j][2] = 0; mipmap. Image 8[i][j][3] = 255; } } 2010 -2학기 가상현실 } 51

for (i = 0; i < 4; i++) { for (j = 0; j < 4; j++) { mipmap. Image 4[i][j][0] mipmap. Image 4[i][j][1] mipmap. Image 4[i][j][2] mipmap. Image 4[i][j][3] } for (i = 0; i < 2; i++) { for (j = 0; j < 2; j++) { mipmap. Image 2[i][j][0] mipmap. Image 2[i][j][1] mipmap. Image 2[i][j][2] mipmap. Image 2[i][j][3] } } 2010 -2학기 = = 0; 255; = = 0; 0; 255; 가상현실 } 52

mipmap. Image 1[0][0][0] mipmap. Image 1[0][0][1] mipmap. Image 1[0][0][2] mipmap. Image 1[0][0][3] = = 255; } void init(void) { gl. Enable(GL_DEPTH_TEST); gl. Shade. Model(GL_FLAT); gl. Translatef(0. 0, -3. 6); make. Images(); gl. Pixel. Storei(GL_UNPACK_ALIGNMENT, 1); 2010 -2학기 가상현실 53

ifdef GL_VERSION_1_1 gl. Gen. Textures(1, &tex. Name); gl. Bind. Texture(GL_TEXTURE_2 D, tex. Name); #endif gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_WRAP_S, GL_REPEAT); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_WRAP_T, GL_REPEAT); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_MIN_FILTER, GL_NEAREST_MIPMAP_NEAREST); gl. Tex. Image 2 D(GL_TEXTURE_2 D, 0, GL_RGBA, 32, 0, GL_RGBA, GL_UNSIGNED_BYTE, mipmap. Image 32); 2010 -2학기 가상현실 54

gl. Tex. Image 2 D(GL_TEXTURE_2 D, 1, GL_RGBA, 16, 0, GL_RGBA, GL_UNSIGNED_BYTE, mipmap. Image 16); gl. Tex. Image 2 D(GL_TEXTURE_2 D, 2, GL_RGBA, 8, 8, 0, GL_RGBA, GL_UNSIGNED_BYTE, mipmap. Image 8); gl. Tex. Image 2 D(GL_TEXTURE_2 D, 3, GL_RGBA, 4, 4, 0, GL_RGBA, GL_UNSIGNED_BYTE, mipmap. Image 4); gl. Tex. Image 2 D(GL_TEXTURE_2 D, 4, GL_RGBA, 2, 2, 0, GL_RGBA, GL_UNSIGNED_BYTE, mipmap. Image 2); gl. Tex. Image 2 D(GL_TEXTURE_2 D, 5, GL_RGBA, 1, 1, 0, GL_RGBA, GL_UNSIGNED_BYTE, mipmap. Image 1); gl. Tex. Envf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); gl. Enable(GL_TEXTURE_2 D); } 2010 -2학기 가상현실 55

void display(void) { gl. Clear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); #ifdef GL_VERSION_1_1 gl. Bind. Texture(GL_TEXTURE_2 D, tex. Name); #endif gl. Begin(GL_QUADS); gl. Tex. Coord 2 f(0. 0, 0. 0); gl. Vertex 3 f(-2. 0, -1. 0, 0. 0); gl. Tex. Coord 2 f(0. 0, 8. 0); gl. Vertex 3 f(-2. 0, 1. 0, 0. 0); gl. Tex. Coord 2 f(8. 0, 8. 0); gl. Vertex 3 f(2000. 0, 1. 0, -6000. 0); gl. Tex. Coord 2 f(8. 0, 0. 0); gl. Vertex 3 f(2000. 0, -1. 0, -6000. 0); gl. End(); gl. Flush(); } 2010 -2학기 가상현실 56

void reshape(int w, int h){ gl. Viewport(0, 0, (GLsizei) w, (GLsizei) h); gl. Matrix. Mode(GL_PROJECTION); gl. Load. Identity(); glu. Perspective(60. 0, (GLfloat)w/(GLfloat)h, 1. 0, 30000. 0); gl. Matrix. Mode(GL_MODELVIEW); gl. Load. Identity(); } void keyboard (unsigned char key, int x, int y) { switch (key) { case 27: exit(0); break; default: break; } } 2010 -2학기 가상현실 57

int main(int argc, char** argv) { glut. Init(&argc, argv); glut. Init. Display. Mode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH); glut. Init. Window. Size (500, 500); glut. Init. Window. Position (50, 50); glut. Create. Window (argv[0]); init (); glut. Display. Func(display); glut. Reshape. Func(reshape); glut. Keyboard. Func(keyboard); glut. Main. Loop(); return 0; } 2010 -2학기 가상현실 58

자동화된 밉맵 생성 만약 레벨 0이나 그 이상 최고 해상도의 맵을 만들었다고 가정한다면 glu. Build. D 1 Mipmaps(), glu. Build 2 DMipmaps(), glu. Build 3 DMipmaps() 루틴 은 1 * 1 해상도로 감소하는 피라미드 형태의 밉맵을 만들고 정의 int glu. Build 1 DMipmaps(GLenum target, GLint internal. Format, GLint width, GLenum format, GLenum type, void *texels); int glu. Build 2 DMipmaps(GLenum target, GLint internal. Format, GLint width, GLenum height, GLenum format, GLenum type, void *texels); int glu. Build 3 DMipmpas(GLenum target, GLint internal. Format, GLint width, GLenum height, GLenum depth, GLenum format, GLenum type, void *texels); 일련의 밉맵을 만들고 이미지를 읽기 위해서 gl. Tex. Image*D()를 호출한다. 모든 밉맵들이 성공적으로 만들어지면 0값을 반환하고 실패시 GLU 에러코 드 반환 2010 -2학기 가상현실 60

세부적 제어의 밉맵 레벨 MIN_LOD와 MAX_LOD는 밉맵 축소의 값( , 텍스처 이미지에 폴리 곤으로의 스케일 인자)의 최대, 최소값을 제공 BASE_LEVEL과 MAX_LEVEL을 사용하여 gl. Tex. Parameter*()는 MIN_LOD와 MAX_LOD를 설정 l l gl. Tex. Parameterf(GL_TEXTURE_2 D, GL_TEXTURE_MIN_LOD, 2. 5); gl. Tex. Parameterf(GL_TEXTURE_2 D, GL_TEXTURE_MAX_LOD, 4. 5); 2010 -2학기 가상현실 64

자동화된 밉맵 부분 집합 생성 밉맵 레벨의 발전된 제어를 통해 glu. Build*DMipmaps()로정의된 밉맵의 부 분 집합을 만들 필요가 있다. 밉멥 레벨들의 부분집합의 계산과 읽기를 위하여 glu. Build*DMipmap. Levels()를 호출 l int glu. Build 1 DMipmap. Levels(GLenum target, GLint internal. Format, GLint width, GLenum format, GLenum type, GLint level, GLint base, GLint max, void *texels); l int glu. Build 2 DMipmap. Levels(GLenum target, GLint internal. Format, GLint width, Glint height, GLenum format, GLenum type, GLint level, GLint base, GLint max, void *texels); l int glu. Build 3 DMipmap. Levels(GLenum target, GLint internal. Format, GLint width, Glint height, GLint depth, GLenum format, GLenum type, GLint level, GLint base, GLint max, void *texels); 2010 -2학기 가상현실 65

확대와 축소를 위한 필터링 방법 매개변수 값 GL_TEXTURE_MAG_FLITER GL_NEAREST 또는 GL_LINEAR GL_TEXTURE_MIN_FILTER GL_NEAREST, GL_LINEAR, GL_NEAREST_MIPMAP_NEAREST, GL_NEAREST_MIPMAP_LINEAR, GL_LINEAR_MIPMAP_NEAREST, GL_LINEAR_MIPMAP_LINEAR GL_NEAREST(최근점법): 픽셀의 중심에 가까운 좌표를 가지는 텍셀이 확 대와 축소를 위해 사용 GL_LINEAR(보간법): 픽셀의 중심에 가까이 위치한 텍셀의 2 x 2배열의 조정 된 선형 평균 사용 GL_NEAREST_MIPMAP_NEAREST: 각각의 밉맵내에서 가장 가까운 텍셀값 을 선택 GL_NEAREST_MIPMAP_LINEAR: 각각의 밉맵 내에서 선형적으로 보간 2010 -2학기 가상현실 67

예제 9 -7 텍스처 오브젝트 바인딩: texbind. c #include <GL/glut. h> #include <stdlib. h> #include <stdio. h> #ifdef GL_VERSION_1_1 #define check. Image. Width 64 #define check. Image. Height 64 static GLubyte check. Image[check. Image. Height][check. Image. Width][4]; static GLubyte other. Image[check. Image. Height][check. Image. Width][4]; static GLuint tex. Name[2]; 2010 -2학기 가상현실 73

void make. Check. Images(void) { int i, j, c; for (i = 0; i < check. Image. Height; i++) { for (j = 0; j < check. Image. Width; j++) { c = ((((i&0 x 8)==0)^((j&0 x 8))==0))*255; check. Image[i][j][0] = (GLubyte) c; check. Image[i][j][1] = (GLubyte) c; check. Image[i][j][2] = (GLubyte) c; check. Image[i][j][3] = (GLubyte) 255; c = ((((i&0 x 10)==0)^((j&0 x 10))==0))*255; 2010 -2학기 가상현실 74

other. Image[i][j][0] other. Image[i][j][1] other. Image[i][j][2] other. Image[i][j][3] = = (GLubyte) c; 0; 0; 255; } } } void init(void) { gl. Clear. Color (0. 0, 0. 0); gl. Shade. Model(GL_FLAT); gl. Enable(GL_DEPTH_TEST); 2010 -2학기 가상현실 75

make. Check. Images(); gl. Pixel. Storei(GL_UNPACK_ALIGNMENT, 1); gl. Gen. Textures(2, tex. Name); gl. Bind. Texture(GL_TEXTURE_2 D, tex. Name[0]); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_WRAP_S, GL_CLAMP); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_WRAP_T, GL_CLAMP); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); gl. Tex. Image 2 D(GL_TEXTURE_2 D, 0, GL_RGBA, check. Image. Width, check. Image. Height, 0, GL_RGBA, GL_UNSIGNED_BYTE, check. Image); 2010 -2학기 가상현실 76

gl. Bind. Texture(GL_TEXTURE_2 D, tex. Name[1]); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_WRAP_S, GL_CLAMP); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_WRAP_T, GL_CLAMP); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_MAG_FILTER, GL_NEAREST); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_MIN_FILTER, GL_NEAREST); gl. Tex. Envf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_DECAL); gl. Tex. Image 2 D(GL_TEXTURE_2 D, 0, GL_RGBA, check. Image. Width, check. Image. Height, 0, GL_RGBA, GL_UNSIGNED_BYTE, other. Image); gl. Enable(GL_TEXTURE_2 D); } 2010 -2학기 가상현실 77

void display(void) { gl. Clear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); gl. Bind. Texture(GL_TEXTURE_2 D, tex. Name[0]); gl. Begin(GL_QUADS); gl. Tex. Coord 2 f(0. 0, 0. 0); gl. Vertex 3 f(-2. 0, -1. 0, 0. 0); gl. Tex. Coord 2 f(0. 0, 1. 0); gl. Vertex 3 f(-2. 0, 1. 0, 0. 0); gl. Tex. Coord 2 f(1. 0, 1. 0); gl. Vertex 3 f(0. 0, 1. 0, 0. 0); gl. Tex. Coord 2 f(1. 0, 0. 0); gl. Vertex 3 f(0. 0, -1. 0, 0. 0); gl. End(); 2010 -2학기 가상현실 78

gl. Bind. Texture(GL_TEXTURE_2 D, tex. Name[1]); gl. Begin(GL_QUADS); gl. Tex. Coord 2 f(0. 0, 0. 0); gl. Vertex 3 f(1. 0, -1. 0, 0. 0); gl. Tex. Coord 2 f(0. 0, 1. 0); gl. Vertex 3 f(1. 0, 0. 0); gl. Tex. Coord 2 f(1. 0, 1. 0); gl. Vertex 3 f(2. 41421, 1. 0, -1. 41421); gl. Tex. Coord 2 f(1. 0, 0. 0); gl. Vertex 3 f(2. 41421, -1. 0, -1. 41421); gl. End(); gl. Flush(); } void reshape(int w, int h) { gl. Viewport(0, 0, (GLsizei) w, (GLsizei) h); gl. Matrix. Mode(GL_PROJECTION); 2010 -2학기 가상현실 79

gl. Load. Identity(); glu. Perspective(60. 0, (GLfloat) w/(GLfloat) h, 1. 0, 30. 0); gl. Matrix. Mode(GL_MODELVIEW); gl. Load. Identity(); gl. Translatef(0. 0, -3. 6); } void keyboard(unsigned char key, int x, int y) { switch (key) { case 27: exit(0); break; } } 2010 -2학기 가상현실 80

int main(int argc, char** argv) { glut. Init(&argc, argv); glut. Init. Display. Mode(GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH); glut. Init. Window. Size(250, 250); glut. Init. Window. Position(100, 100); glut. Create. Window(argv[0]); init(); glut. Reshape. Func(reshape); glut. Display. Func(display); glut. Keyboard. Func (keyboard); glut. Main. Loop(); return 0; } 2010 -2학기 가상현실 81

#else int main(int argc, char** argv) { fprintf (stderr, "This program demonstrates a feature which is not in Open. GL Version 1. 0. n"); fprintf (stderr, "If your implementation of Open. GL Version 1. 0 has the right extensions, n"); fprintf (stderr, "you may be able to modify this program to make it run. n"); return 0; } #endif 2010 -2학기 가상현실 82

S: source, f: fragment l 텍스처의 교체와 변조 함수 (GL_REPLACE, GL_MODULATE) 베이스 내부 형식 텍스처 교체 함 텍스처 변조 함 수 수 GL_DECAL GL_ALPHA C = Cf A = As C = Cf A = Af. As 정의되지 않음 GL_LUMINANCE C = Cs A = Af C = Cf. Ls A = As 정의되지 않음 GL_ALUMINANCE _ALPHA C = Cs C = Af C = Cf. Ls A = Af. As 정의되지 않음 GL_INTENSITY C = Cs A = If C = Cf. Ls A = Af. Is 정의되지 않음 GL_RGB C = Cs A = Af C = Cf. Cs A = As C = Cs A = Af GL_RGBA C = Cs A = Af C = Cf. Cs A = Af. As C = Cf(1 -As)+Cs. As A = Af 2010 -2학기 가상현실 88

c: GL_TEXTURE_ENV_COLOR l 텍스처의 전사와 블렌딩 함수 (GL_BLEND, GL_ADD) 베이스 내부 형식 GL_BLEND 함수 GL_ADD 함수 GL_ALPHA C = Ct A = Af. As C = Cf A = Af. As GL_LUMINANCE C=Cf(1 -Cs)+Cc. Cs A = Af C = Cf + Cs A = Af GL_LUMINANCE_A LPHA C=Cf(1 -Cs)+Cc. Cs A = Af. As C = Cf + Cs A = Af. As GL_INTENSITY C=Cf(1 -Cs)+Cc. Cs A=Af(1 -As)+Ac. As C = Cf + Cs A = Af + As GL_RGB C=Cf(1 -Cs)+Cc. Cs A = Af C = Cf + Cs A = Af GL_RGBA C=Cf(1 -Cs)+Cc. Cs A = Af. As C = Cf + Cs A = Af. As 2010 -2학기 가상현실 89

예제: 9 -1에서 gl. Begin(GL_QUADS); gl. Tex. Coord 2 f(0. 0, gl. Tex. Coord 2 f(3. 0, gl. End(); 2010 -2학기 0. 0); 3. 0); 0. 0); gl. Vertex 3 f(-2. 0, -1. 0, 0. 0); gl. Vertex 3 f(-2. 0, 1. 0, 0. 0); gl. Vertex 3 f(0. 0, -1. 0, 0. 0); 3. 0); 0. 0); gl. Vertex 3 f(1. 0, -1. 0, 0. 0); gl. Vertex 3 f(1. 0, 0. 0); gl. Vertex 3 f(2. 41421, 1. 0, -1. 41421); gl. Vertex 3 f(2. 41421, -1. 0, -1. 41421); 가상현실 94

GL_REPEAT 래핑의 결과 gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_WRAP_S, GL_REPEAT); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_WRAP_T, GL_REPEAT); 2010 -2학기 가상현실 95

GL_CLAMP 래핑의 결과 gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_WRAP_S, GL_CLAMP); gl. Tex. Parameteri(GL_TEXTURE_2 D, GL_TEXTURE_WRAP_T, GL_CLAMP); 2010 -2학기 가상현실 96

gl. Tex. Parameter*() 매개변수들 매개변수 변수들 GL_TEXTURE_WRAP_S GL_CLAMP, GL_CLAMP_TO_EDGE, GL_REPEAT GL_TEXTURE_WRAP_T GL_CLAMP, GL_CLAMP_TO_EDGE, GL_REPEAT GL_TEXTURE_WRAP_R GL_CLAMP, GL_CLAMP_TO_EDGE, GL_REPEAT GL_TEXTURE_MAG_FILTER GL_CLAMP, GL_LINEAR GL_TEXTURE_MIN_FILTER GL_NEAREST, GL_LINEAR, GL_NEAREST_MIPMAP_NEAREST, GL_NEAREST_MIPMAP_LINEAR, GLLINEAR_MIPMAP_NEAREST, GL_LINER_MIPMAP_LINEAR 2010 -2학기 가상현실 97

텍스처 좌표 자동으로 산출하기 모델의 윤곽을 그리거나, 임의의 빛나는 모델의 환경에서 도출되는 반사를 가짜로 표현하기 위해 텍스처 매핑을 사용 가능 l gl. Texture. Coord*() 보다는 Open. GL이 자동으로 텍스처 좌표를 산출하도록 한다. void gl. Tex. Gen{ifd}(GLenum coord, GLenum pname, TYPE param); void gl. Tex. Gen{idf}v(GLenum coord, GLenum pname, TYPE *param); l l l 첫 번째 매개변수 coord는 텍스처 좌표가 산출되는지를 지시하 기 위해 GL_S, GL_T, GL_R, GL_Q 사용 pname은 GL_TEXTURE_GEN_MODE, GL_OBJECT_PLANE, GL_EYE_PLANE param은 GL_OBJECT_LINEAR, GL_EYE_LINEAR, GL_SPHERE_LINEAR 2010 -2학기 가상현실 99

예제 9 -8 자동 텍스처 좌표 생성: texgen. c #include <GL/glut. h> #include <stdlib. h> #include <stdio. h> #define stripe. Image. Width 32 GLubyte stripe. Image[4*stripe. Image. Width]; #ifdef GL_VERSION_1_1 static GLuint tex. Name; #endif 2010 -2학기 가상현실 103

void make. Stripe. Image(void){ int j; for (j = 0; j < stripe. Image. Width; j++) { stripe. Image[4*j] = (GLubyte) ((j<=4) ? 255 : 0); stripe. Image[4*j+1] = (GLubyte) ((j>4) ? 255 : 0); stripe. Image[4*j+2] = (GLubyte) 0; stripe. Image[4*j+3] = (GLubyte) 255; } } static GLfloat xequalzero[] = {1. 0, 0. 0}; static GLfloat slanted[] = {1. 0, 0. 0}; static GLfloat *current. Coeff; 2010 -2학기 가상현실 104

static GLenum current. Plane; static GLint current. Gen. Mode; void init(void) { gl. Clear. Color (0. 0, 0. 0); gl. Enable(GL_DEPTH_TEST); gl. Shade. Model(GL_SMOOTH); make. Stripe. Image(); gl. Pixel. Storei(GL_UNPACK_ALIGNMENT, 1); #ifdef GL_VERSION_1_1 gl. Gen. Textures(1, &tex. Name); gl. Bind. Texture(GL_TEXTURE_1 D, tex. Name); 2010 -2학기 가상현실 105

#endif gl. Tex. Parameteri(GL_TEXTURE_1 D, GL_TEXTURE_WRAP_S, GL_REPEAT); gl. Tex. Parameteri(GL_TEXTURE_1 D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); gl. Tex. Parameteri(GL_TEXTURE_1 D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); #ifdef GL_VERSION_1_1 gl. Tex. Image 1 D(GL_TEXTURE_1 D, 0, GL_RGBA, stripe. Image. Width, 0, GL_RGBA, GL_UNSIGNED_BYTE, stripe. Image); #else gl. Tex. Image 1 D(GL_TEXTURE_1 D, 0, 4, stripe. Image. Width, 0, GL_RGBA, GL_UNSIGNED_BYTE, stripe. Image); #endif 2010 -2학기 가상현실 106

gl. Tex. Envf(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE); current. Coeff = xequalzero; current. Gen. Mode = GL_OBJECT_LINEAR; current. Plane = GL_OBJECT_PLANE; gl. Tex. Geni(GL_S, GL_TEXTURE_GEN_MODE, current. Gen. Mode); gl. Tex. Genfv(GL_S, current. Plane, current. Coeff); gl. Enable(GL_TEXTURE_GEN_S); gl. Enable(GL_TEXTURE_1 D); gl. Enable(GL_CULL_FACE); gl. Enable(GL_LIGHTING); gl. Enable(GL_LIGHT 0); gl. Enable(GL_AUTO_NORMAL); 2010 -2학기 가상현실 107

gl. Enable(GL_NORMALIZE); gl. Front. Face(GL_CW); gl. Cull. Face(GL_BACK); gl. Materialf (GL_FRONT, GL_SHININESS, 64. 0); } void display(void) { gl. Clear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); gl. Push. Matrix (); gl. Rotatef(45. 0, 0. 0, 1. 0); 2010 -2학기 가상현실 108

#ifdef GL_VERSION_1_1 gl. Bind. Texture(GL_TEXTURE_1 D, tex. Name); #endif glut. Solid. Teapot(2. 0); gl. Pop. Matrix (); gl. Flush(); } void reshape(int w, int h) { gl. Viewport(0, 0, (GLsizei) w, (GLsizei) h); gl. Matrix. Mode(GL_PROJECTION); gl. Load. Identity(); 2010 -2학기 가상현실 109

if (w <= h) gl. Ortho (-3. 5, -3. 5*(GLfloat)h/(GLfloat)w, -3. 5, 3. 5); else gl. Ortho (-3. 5*(GLfloat)w/(GLfloat)h, -3. 5, 3. 5); gl. Matrix. Mode(GL_MODELVIEW); gl. Load. Identity(); } 2010 -2학기 가상현실 110

void keyboard (unsigned char key, int x, int y) { switch (key) { case 'e': case 'E': current. Gen. Mode = GL_EYE_LINEAR; current. Plane = GL_EYE_PLANE; gl. Tex. Geni(GL_S, GL_TEXTURE_GEN_MODE, current. Gen. Mode); gl. Tex. Genfv(GL_S, current. Plane, current. Coeff); glut. Post. Redisplay(); break; 2010 -2학기 가상현실 111

case 'o': case 'O': current. Gen. Mode = GL_OBJECT_LINEAR; current. Plane = GL_OBJECT_PLANE; gl. Tex. Geni(GL_S, GL_TEXTURE_GEN_MODE, current. Gen. Mode); gl. Tex. Genfv(GL_S, current. Plane, current. Coeff); glut. Post. Redisplay(); break; case 's': case 'S': current. Coeff = slanted; gl. Tex. Genfv(GL_S, current. Plane, current. Coeff); glut. Post. Redisplay(); break; 2010 -2학기 가상현실 112

case 'x': case 'X': current. Coeff = xequalzero; gl. Tex. Genfv(GL_S, current. Plane, current. Coeff); glut. Post. Redisplay(); break; case 27: exit(0); break; default: break; } } 2010 -2학기 가상현실 113

int main(int argc, char** argv) { glut. Init(&argc, argv); glut. Init. Display. Mode (GLUT_SINGLE | GLUT_RGB | GLUT_DEPTH); glut. Init. Window. Size(256, 256); glut. Init. Window. Position(100, 100); glut. Create. Window (argv[0]); init (); glut. Display. Func(display); glut. Reshape. Func(reshape); glut. Keyboard. Func(keyboard); glut. Main. Loop(); return 0; } 2010 -2학기 가상현실 114