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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.

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CH6 Texture

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  1. CH6 Texture

  2. 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

  3. Before coding…2/2 • Add GlAux.Lib into your project.

  4. 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

  5. Example Program 2/4 void LoadTexture(char* filename){ img = auxDIBImageLoad(filename); glGenTextures(TEX_NUM, texObject); glBindTexture(GL_TEXTURE_2D, texObject[0]); #ifdef MIPMAP gluBuild2DMipmaps(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); #else glTexImage2D(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); #endif glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST); }

  6. 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(); }

  7. 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(); }

  8. Check.bmp Width/Height: 256/256

  9. 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.

  10. Texture Object • void glGenTextures( GLsizein,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( GLuinttexture); • To determine if a name corresponds to a texture. • http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/glfunc03_7cv9.asp

  11. Bind texture • void glBindTexture( GLenumtarget,GLuinttexture); • 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( GLsizein,const GLuint *textures); • Delete named textures. • http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/glfunc01_6vqr.asp

  12. Specifies 2D texture image 1/4 • void glTexImage2D( GLenumtarget, GLintlevel, GLintinternalformat, GLsizeiwidth, GLsizeiheight, GLintborder, GLenumformat, GLenumtype, const GLvoid *pixels );

  13. 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

  14. 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.

  15. 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…)

  16. Apply texture to objects 1/3 • void glTexEnv{fi}(GLenumtarget,GLenumpname,GLfloatparam ); • 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

  17. Base Internal Format GL_REPLACE GL_MODULATE GL_ADD GL_ALPHA C = Cf, A = At C = Cf, A = AfAt C=Cf, A=AfAt GL_LUMINANCE C = Lt, A = Af C = CfLt, A = Af C=Cf+CT, A=Af GL_LUMINANCE_ALPHA C = Lt, A = At C = CfLt, A = AfAt C=Cf+Ct, A=AfAt GL_INTENSITY C = It, A = It C = CfIt, A = AfIt C=Cf+Ct, A=Af+At GL_RGB C = Ct, A = Af C = CfCt, A = Af C=Cf+Ct, A=Af GL_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 = AfAt GL_LUMINANCE Undefined C = Cf(1-Lt)+CcLt, A = Af GL_LUMINANCE_ALPHA Undefined C = Cf(1-Lt)+CcLt, A = AfAt GL_INTENSITY Undefined C = Cf(1-It)+CcIt, A = Af(1-It)+AcIt GL_RGB C = Ct, A = Af C = Cf(1-Ct)+CcCt, A = Af GL_RGBA C = Cf(1-At)+CtAt, A = At C = Cf(1-Ct)+CcCt, A = AfAt Apply texture to objects 2/3 Xc indicates the values assigned with GL_TEXTURE_ENV_COLOR. * GL_TEXTURE_ENV_COLOR is defined by glGetTexEnvfv Xt 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.

  18. Apply texture to objects 3/3 • glTexEnv{fi}v(GLenumtarget,GLenumpname,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

  19. Texture parameter 1/5 • glTexParameter{if}(GLenumtarget,GLenumpname,GLfloatparam ) • 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

  20. Texture parameter 2/5 pname param GL_TEXTURE_WARP_S GL_TEXTURE_WARP_T GL_REPEAT, GL_CLAMP GL_TEXTURE_MAG_FILTER GL_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

  21. Texture parameter 3/5 Clamp both S, T • WARP Repeat both S, T Repeat T but Clamp S

  22. 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

  23. Texture parameter 5/5 • GL_LINEAR • GL_NEARST pixel Get average color... texel • GL_NEAREST_MIPMAP_XXXXXX • Find the most closely match mipmap • GL_LINEAR_MIPMAP_XXXXXXX • Find the most 2 closely match mipmap and get average.

  24. Build mip-maps 1/3 • int gluBuild2DMipmaps( GLenumtarget, GLintcomponents, GLintwidth, GLintheight, GLenumformat, GLenumtype, const void *data); • http://msdn.microsoft.com/library/default.asp?url=/library/en-us/opengl/glufnc01_406r.asp

  25. 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.

  26. Build mip-maps 3/3 without mip-map with mip-map

  27. 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);

  28. 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(); }

  29. 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); }

  30. 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); }

  31. 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(); }

  32. environment.bmp Width/Height: 128/128

  33. Automatic Texture-Coordinate Generation 1/4 • glTexGen{dfi}(GLenumcoord,GLenumpname,GLdoubleparam); • 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

  34. Automatic Texture-Coordinate Generation 2/4 • glTexGen{dfi}v(GLenumcoord,GLenumpname, 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

  35. 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); }

  36. Automatic Texture-Coordinate Generation 4/4 • If change parameters… • par[] = {1, 0, 0, 0} • par[] = {0, 1, 0, 0}

  37. 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); }

  38. So easy…v(￣︶￣)y

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