/*
Software rendering library.

Cooridnate systems:
- Pixel coordinates (i,j) refer to the center of the pixel.
  Thus, real-valued coordinates (x,y) with no fractional part point at the pixel center.
- Viewport origin is the top-left corner of the screen.
  The viewport axes extend down and to the right.

Multi-threading:
- Internal resources (swgfx context) are externally synchronized.
- External resources (colour buffer) are internally synchronized.
*/
#pragma once

#include <stddef.h>
#include <stdint.h>

typedef float R;

typedef struct sgVec2i { int x, y; }       sgVec2i;
typedef struct sgVec2  { R   x, y; }       sgVec2;
typedef struct sgVec3  { R   x, y, z; }    sgVec3;
typedef struct sgVec4  { R   x, y, z, w; } sgVec4;

typedef sgVec3 sgNormal;

typedef struct sgQuadi { sgVec2i p0, p1; }     sgQuadi;
typedef struct sgQuad  { sgVec2  p0, p1; }     sgQuad;
typedef struct sgTri2  { sgVec2  p0, p1, p2; } sgTri2;
typedef struct sgTri3  { sgVec3  p0, p1, p2; } sgTri3;

// TODO: Should we use real-valued colours?
typedef struct sgPixel { uint8_t r, g, b, a; } sgPixel;

typedef struct swgfx swgfx;

swgfx* sgNew();
void   sgDel(swgfx**);

// TODO: Write client app first, then implement the functions below in the C file.

void sgColourBuffer(swgfx*, sgVec2i dimensions, sgPixel* buffer);
void sgPresent     (swgfx*, sgVec2i dimensions, sgPixel* screen);

void sgCam        (swgfx*, sgVec3 position, sgVec3 forward);
void sgOrtho      (swgfx*, R left, R right, R top, R bottom, R near, R far);
void sgPerspective(swgfx*, R fovy, R aspect, R near, R far);
void sgViewport   (swgfx*, int x0, int y0, int width, int height);

void sgClear(swgfx*);
void sgPixels(swgfx*, size_t count, const sgVec2i* positions, sgPixel colour);
void sgQuads (swgfx*, size_t count, const sgQuad*);
void sgQuadsi(swgfx*, size_t count, const sgQuadi*);
void sgTriangles2    (swgfx*, size_t count, const sgTri2*);
void sgTriangleStrip2(swgfx*, size_t count, const sgVec2*);
void sgTriangles     (swgfx*, size_t count, const sgTri3*, const sgNormal*);
void sgTriangleStrip (swgfx*, size_t count, const sgVec3*, const sgNormal*);

void sgCheck(swgfx*);

// Memory
#define SG_ALIGN 64
#define SG_ALIGN_PTR(P) ((uintptr_t)(P) & (~(SG_ALIGN-1)))
#define SG_ALIGN_ALLOC(COUNT, TYPE) (TYPE*)sgAlloc(1, COUNT * sizeof(TYPE))
#define SG_FREE(PP) sgFree((void**)PP)
void* sgAlloc(size_t count, size_t size);
void  sgFree(void**);