first commit
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149ab4c305
2
.gitignore
vendored
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2
.gitignore
vendored
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/perspective
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*.o
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10
Makefile
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10
Makefile
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CFLAGS= -Wfatal-errors -Wall -Wextra $(shell pkgconf --cflags sdl2)
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LDFLAGS= -s $(shell pkgconf --libs sdl2)
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all: perspective
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perspective: main.o
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$(CC) $^ -o $@ $(LDFLAGS)
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%.o: %.c
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$(CC) -c $^ -o $@ $(CFLAGS)
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clean:
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$(RM) *.o perspective
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200
main.c
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200
main.c
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/*******
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* Convert 3d points into 2d points
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* and display them to the screen
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*******/
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#include<stdio.h>
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#include<unistd.h>
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#include<fcntl.h>
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#include<stdint.h>
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#include<stdbool.h>
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#include<SDL2/SDL.h>
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typedef struct Point3d
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{
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float x;
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float y;
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float z;
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} Point3d;
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typedef struct Quad
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{
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Point3d p[4];
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} Quad;
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typedef struct Point2d
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{
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float x;
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float y;
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} Point2d;
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typedef struct Cube
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{
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float x;
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float y;
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float z;
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float w;
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float h;
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float d;
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} Cube;
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Point2d rasterize(Point3d cam,Point3d p)
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{
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Point2d p2={0};
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if(!p.z)return p2; // divide by zero error
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/* p2.x=-p.x/p.z; */
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/* p2.y=-p.y/p.z; */
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p2.x=(p.x-cam.x)/(p.z-cam.z);
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p2.y=(p.y-cam.y)/(p.z-cam.z);
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return p2;
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}
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void print_point3d(Point3d p)
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{
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printf("(%g,%g,%g)\n",p.x,p.y,p.z);
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}
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void print_point2d(Point2d p)
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{
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printf("(%g,%g)\n",p.x,p.y);
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}
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#define cube_wire(cam,r)\
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do{\
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if(r.z>cam.z){\
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Point2d _p[4];\
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Point3d _p3[4];\
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_p3[0]=(Point3d){.x=r.x,.y=r.y,.z=r.z};\
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_p3[1]=(Point3d){.x=r.x+r.w,.y=r.y,.z=r.z};\
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_p3[2]=(Point3d){.x=r.x,.y=r.y+r.h,.z=r.z};\
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_p3[3]=(Point3d){.x=r.x+r.w,.y=r.y+r.h,.z=r.z};\
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for(int i=0;i<4;++i)\
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_p[i]=rasterize(cam,_p3[i]);\
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SDL_RenderDrawLine(ren,width/2+_p[0].x,height/2-_p[0].y,width/2+_p[1].x,height/2-_p[1].y);\
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SDL_RenderDrawLine(ren,width/2+_p[2].x,height/2-_p[2].y,width/2+_p[3].x,height/2-_p[3].y);\
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SDL_RenderDrawLine(ren,width/2+_p[0].x,height/2-_p[0].y,width/2+_p[2].x,height/2-_p[2].y);\
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SDL_RenderDrawLine(ren,width/2+_p[1].x,height/2-_p[1].y,width/2+_p[3].x,height/2-_p[3].y);\
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}\
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}while(0)
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int main(void)
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{
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Point2d p2;
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Point3d p3={.x=2,.y=3,.z=1};
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Point3d cam={0};
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Quad q1;
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Quad q2;
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SDL_Renderer*ren;
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SDL_Window*win;
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bool running=true;
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const int height=240;
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const int width=320;
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Cube cube={.x=5,.y=4,.w=20,.h=20,.z=1};
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Cube cube2={.x=5,.y=4,.w=20,.h=20,.z=2};
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// Init SDL
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SDL_Init(SDL_INIT_EVERYTHING);
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win=SDL_CreateWindow("",SDL_WINDOWPOS_UNDEFINED,
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SDL_WINDOWPOS_UNDEFINED,width,height,0);
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ren=SDL_CreateRenderer(win,-1,0);
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q1.p[0]=(Point3d){.x=1,.y=20,.z=1};
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q1.p[1]=(Point3d){.x=20,.y=20,.z=1};
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q1.p[2]=(Point3d){.x=1,.y=1,.z=1};
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q1.p[3]=(Point3d){.x=20,.y=1,.z=1};
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q2.p[0]=(Point3d){.x=1,.y=20,.z=2};
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q2.p[1]=(Point3d){.x=20,.y=20,.z=2};
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q2.p[2]=(Point3d){.x=1,.y=1,.z=2};
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q2.p[3]=(Point3d){.x=20,.y=1,.z=2};
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/* for(int i=0;i<4;++i) */
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/* { */
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/* Point2d p=rasterize(q1.p[i]); */
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/* print_point2d(p); */
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/* } */
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// Convert points
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print_point3d(p3);
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p2=rasterize(cam,p3);
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print_point2d(p2);
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// Event loop
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while(running)
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{
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SDL_Event evt;
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// Check events
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if(SDL_PollEvent(&evt))
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{
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switch(evt.type)
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{
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case SDL_QUIT:running=false;break;
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case SDL_KEYDOWN:
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switch(evt.key.keysym.sym)
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{
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case SDLK_ESCAPE:
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case SDLK_q:
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running=false;
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break;
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case SDLK_LEFT:--cam.x;break;
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case SDLK_RIGHT:++cam.x;break;
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case SDLK_UP:++cam.y;break;
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case SDLK_DOWN:--cam.y;break;
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case SDLK_w:cam.z+=0.1;break;
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case SDLK_s:cam.z-=0.1;break;
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}
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break;
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}
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}
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// Render
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SDL_SetRenderDrawColor(ren,0,0,0,0);
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SDL_RenderClear(ren);
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SDL_SetRenderDrawColor(ren,128,128,128,0);
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SDL_RenderDrawLine(ren,width/2,0,width/2,height);
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SDL_RenderDrawLine(ren,0,height/2,width,height/2);
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// Draw points
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SDL_SetRenderDrawColor(ren,255,255,255,0);
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/* SDL_RenderDrawPoint(ren,p2.x,p2.y); */
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/* for(int i=0;i<4;++i) */
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/* { */
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/* Point2d p; */
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/* p=rasterize(q1.p[i]); */
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/* SDL_RenderDrawPoint(ren,width/2+p.x,height/2-p.y); */
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/* */
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/* p=rasterize(q2.p[i]); */
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/* SDL_RenderDrawPoint(ren,width/2+p.x,height/2-p.y); */
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/* } */
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/* SDL_SetRenderDrawColor(ren,255,255,255,0); */
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/* quad_wire(q1); */
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/* SDL_SetRenderDrawColor(ren,192,192,192,0); */
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/* quad_wire(q2); */
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SDL_SetRenderDrawColor(ren,255,255,255,0);
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cube_wire(cam,cube);
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SDL_SetRenderDrawColor(ren,192,192,192,0);
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cube_wire(cam,cube2);
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SDL_RenderPresent(ren);
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usleep(20000);
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}
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// Quit
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if(win)SDL_DestroyWindow(win);
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if(ren)SDL_DestroyRenderer(ren);
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SDL_Quit();
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}
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