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PROCEDURAL TEXTURES using OPENGL In this article, I don't speak about the Procedural Textures teori, you can found very good information in this page and here (spain) I write this page because a don't found a simple example to make a Procedural Texture,now I have compiled information to develop a OPENGL Procedural Texture to making futures landscape. Now the code is simple ,is the better moment to explaint it We are using Linux,OpenGl and C++. |
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PerlinNoise map .27-01-03 //To compile $ gcc -O NAME.c -o OUTPUTNAME -lglut #include <GL/glut.h> #include <stdlib.h> #include <stdio.h> #define ImageWidth 524 #define ImageHeight 524 GLubyte MatrixImage[ImageHeight][ImageWidth][3]; float RGB [2]; static GLint height; float InterPolation(float a, float b, float c) { return a+(b-a)*c*c*(3-2*c); } float InterLinear(float a, float b, float c) { return a*(1-c)+b*c; } float Noise( int x) { x = (x<<13)^x; return (((x * (x * x * 15731 + 789221) + 1376312589) & 0x7fffffff) / 2147483648.0); } float PerlinNoise(float x,float y,int width,int octaves,int seed,double periode){ double a,b,value,freq,tam_pas,zone_x,zone_y; int s,box,num,step_x,step_y; int amplitude=120; int noisedata; freq=1/(float)(periode); for ( s=0;s<octaves;s++){ num=(int)(width*freq); step_x=(int)(x*freq); step_y=(int)(y*freq); zone_x=x*freq-step_x; zone_y=y*freq-step_y; box=step_x+step_y*num; noisedata=(box+seed); a=InterPolation(Noise(noisedata),Noise(noisedata+1),zone_x); b=InterPolation(Noise(noisedata+num),Noise(noisedata+1+num),zone_x); value=InterPolation(a,b,zone_y)*amplitude; } return value; } void colour (float valor){ int r=InterLinear(valor,0,0 ); int g=InterLinear(0,0,valor); int b=InterLinear(0,0,valor); RGB[0]=r; RGB[1]=g; RGB[2]=b; } void makeImage(void) { int x,y; float color; int seed; int width; float disp1,disp2,disp3,disp4,disp5,disp6,scale; for(y=0;y< ImageWidth; y++){ for(x=0;x<ImageHeight; x++){ scale=1; width=12413; seed=63; disp1= PerlinNoise(x*scale,y*scale,width,1,seed,100); disp2= PerlinNoise(x*scale,y*scale,width,1,seed,25); disp3= PerlinNoise(x*scale,y*scale,width,1,seed,12.5); disp4= PerlinNoise(x*scale,y*scale,width,1,seed,6.25); disp5= PerlinNoise(x*scale,y*scale,width,1,seed,3.125); disp6= PerlinNoise(x*scale,y*scale,width,1,seed,1.56); colour((int)disp1+(int)(disp2*.25)+(int)(disp3*.125)+(int)(disp4*.0625)+(int)(disp5*.03125)+(int)(disp6*.0156)); MatrixImage[x][y][0] = RGB[0]; MatrixImage[x][y][1] = RGB[1]; MatrixImage[x][y][2] = RGB[2]; }} } void init(void) { glClearColor (0.0, 0.0, 0.0, 0.0); glShadeModel(GL_FLAT); makeImage(); glPixelStorei(GL_UNPACK_ALIGNMENT, 1); } void display(void) { glClear(GL_COLOR_BUFFER_BIT); glRasterPos2i(0, 0); glDrawPixels(ImageWidth, ImageHeight, GL_RGB, GL_UNSIGNED_BYTE, MatrixImage); glFlush(); } void reshape(int w, int h) { glViewport(0, 0, (GLsizei) w, (GLsizei) h); height = (GLint) h; glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluOrtho2D(0.0, (GLdouble) w, 0.0, (GLdouble) h); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); } void keyboard(unsigned char key, int x, int y) { switch (key) { case 27: exit(0); break; default: break; } } int main(int argc, char** argv) { glutInit(&argc, argv); glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB); glutInitWindowSize(524, 524); glutInitWindowPosition(100, 100); glutCreateWindow(argv[0]); init(); glutDisplayFunc(display); glutReshapeFunc(reshape); glutKeyboardFunc(keyboard); glutMainLoop(); return 0; } |
PerlinNoise(x*scale,y*scale,width,1,seed,100); |
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PerlinNoise(x*scale,y*scale,width,1,seed,25); |
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PerlinNoise(x*scale,y*scale,width,1,seed,12.5); |
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PerlinNoise(x*scale,y*scale,width,1,seed,6.25); |
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PerlinNoise(x*scale,y*scale,width,1,seed,3.125); |
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PerlinNoise(x*scale,y*scale,width,1,seed,1.56); |
colour((int)disp1+(int)(disp2*.25)+(int)(disp3*.125)+(int)(disp4*.0625)+(int)(disp5*.03125)+(int)(disp6*.0156)); 
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and "seed" variable make a other imagex Your can use "scale" variable to scale a imagen box 
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