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add scratchpixel functions to renderer w/o implementing them. read/wr…
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…ite texture functions Texture arguments are const
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@bgates747
bgates747 committed Aug 28, 2024
1 parent 65a0fef commit 585f434
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Showing 3 changed files with 141 additions and 7 deletions.
136 changes: 135 additions & 1 deletion video/pingo/render/renderer.c
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Original file line number Diff line number Diff line change
@@ -1,5 +1,7 @@
#include <string.h>
#include <stdio.h>
#include <math.h>

#include "renderer.h"
#include "sprite.h"
#include "pixel.h"
Expand All @@ -9,6 +11,18 @@
#include "rasterizer.h"
#include "object.h"

#define Z_THRESHOLD -0.000001f

// FORWARD DECLARATIONS
static inline void persp_divide(struct Vec3f* p);
static inline void to_raster(const Vec2i size, struct Vec3f* const p);
static inline void tri_bbox(const Vec3f* const p0, const Vec3f* const p1, const Vec3f* const p2, float* const bbox);
static inline float edge(const Vec3f* const a, const Vec3f* const b, const Vec3f* const test);
static Pixel shade(const Texture* texture, Vec2f uv);
static inline void rasterize(int x0, int y0, int x1, int y1, const Vec3f* const p0, const Vec3f* const p1, const Vec3f* const p2, const Vec2f* const uv0, const Vec2f* const uv1, const Vec2f* const uv2, const Texture* const texture, const Vec2i scrSize, Renderer* r);
void mat4ExtractPerspective(const Mat4* m, float* near, float* far, float* aspect, float* fov);
Pixel rgba2222_to_pixel(uint8_t data);

#if DEBUG
extern void show_pixel(float x, float y, uint8_t a, uint8_t b, uint8_t g, uint8_t r);
#endif
Expand Down Expand Up @@ -116,7 +130,7 @@ int renderObject(Mat4 object_transform, Renderer * r, Renderable ren) {
c = mat4MultiplyVec4( &c, &m);

float diffuseLight = 1.0; // default to full illumination from all directions
if (true) { // set to true for lighting effects at the expense of performance
if (false) { // set to true for lighting effects at the expense of performance
//Calc Face Normal
Vec3f na = vec3fsubV(*((Vec3f*)(&a)), *((Vec3f*)(&b)));
Vec3f nb = vec3fsubV(*((Vec3f*)(&a)), *((Vec3f*)(&c)));
Expand Down Expand Up @@ -301,3 +315,123 @@ int rendererSetCamera(Renderer * r, Vec4i rect) {
};
return 0;
}

// SCRATCHPIXEL FUNCTIONS
static inline void persp_divide(struct Vec3f* p) {
if (p->z > Z_THRESHOLD) {
p->z = Z_THRESHOLD; // Prevent division by zero
}
float inv_z = 1.0f / p->z; // Use the z value directly without flipping sign
p->x *= inv_z; // Normalize x by z
p->y *= inv_z; // Normalize y by z
}

static inline void to_raster(const Vec2i size, struct Vec3f* const p) {
p->x = (p->x + 1) * 0.5f * (float)size.x;
p->y = (1 - p->y) * 0.5f * (float)size.y;
}

static inline void tri_bbox(const Vec3f* const p0, const Vec3f* const p1, const Vec3f* const p2, float* const bbox) {
bbox[0] = MIN(MIN(p0->x, p1->x), p2->x);
bbox[1] = MIN(MIN(p0->y, p1->y), p2->y);
bbox[2] = MAX(MAX(p0->x, p1->x), p2->x);
bbox[3] = MAX(MAX(p0->y, p1->y), p2->y);
}

static inline float edge(const Vec3f* const a, const Vec3f* const b, const Vec3f* const test) {
return (test->x - a->x) * (b->y - a->y) - (test->y - a->y) * (b->x - a->x);
}

static Pixel shade(const Texture* texture, Vec2f uv) {
if (texture->frameBuffer != NULL) {
float u = uv.x;
float v = uv.y;

// Convert normalized coordinates to texel coordinates
Vec2i texel;
texel.x = (int)MIN(u * texture->size.x, texture->size.x - 1);
texel.y = (int)MIN(v * texture->size.y, texture->size.y - 1);

// Get the color from the texture at the texel position
// return texture->frameBuffer[texel.y * texture->size.x + texel.x];
return texture_read(texture, texel);
}
}

static inline void rasterize(int x0, int y0, int x1, int y1, const Vec3f* const p0, const Vec3f* const p1, const Vec3f* const p2, const Vec2f* const uv0, const Vec2f* const uv1, const Vec2f* const uv2, const Texture* const texture, const Vec2i scrSize, Renderer* r) {
float inv_area = 1.0f / edge(p0, p1, p2);

Vec3f pixel, sample;
pixel.y = y0;

for (int scrY = y0, row = y0 * scrSize.x; scrY <= y1; ++scrY, pixel.y += 1, row += scrSize.x) {
pixel.x = x0;
for (int scrX = x0, index = row + x0; scrX <= x1; ++scrX, pixel.x += 1, ++index) {
sample.x = pixel.x + 0.5f;
sample.y = pixel.y + 0.5f;

float w0 = edge(p1, p2, &sample) * inv_area;
float w1 = edge(p2, p0, &sample) * inv_area;
float w2 = edge(p0, p1, &sample) * inv_area;

if (w0 >= 0 && w1 >= 0 && w2 >= 0) {
float one_over_z = w0 / p0->z + w1 / p1->z + w2 / p2->z;
float z = 1.0f / one_over_z;

if (depth_check(r->backEnd->getZetaBuffer(r, r->backEnd), scrX + scrY * scrSize.x, z)) {
continue;
}

depth_write(r->backEnd->getZetaBuffer(r, r->backEnd), scrX + scrY * scrSize.x, z);

// Interpolate the texture coordinates
Vec2f uv;
uv.x = (uv0->x * w0 + uv1->x * w1 + uv2->x * w2) * z;
uv.y = (uv0->y * w0 + uv1->y * w1 + uv2->y * w2) * z;

// Shade the pixel and update the color buffer
Pixel color = shade(texture, uv);

backendDrawPixel(r, &r->frameBuffer, (Vec2i) { scrX, scrY }, color, 1.0f);
}
}
}
}

// FUNCTIONS BELOW ARE NOT FROM SCRATCHPIXEL
// BUT WE PUT THEM HERE BECAUSE THEY'RE NOT PINGO EITHER
void mat4ExtractPerspective(const Mat4* m, float* near, float* far, float* aspect, float* fov) {
// Extract the relevant elements from the matrix
float w = m->elements[0]; // Element at (0, 0)
float h = m->elements[5]; // Element at (1, 1)
float a = m->elements[10]; // Element at (2, 2)
float b = m->elements[14]; // Element at (2, 3)

// Calculate the aspect ratio and field of view
*aspect = w / h;
*fov = 2.0 * atan(1.0 / h);

// Calculate the near and far planes
*far = b / (a + 1.0);
*near = b / (a - 1.0);
}

// Decode the rgba2222 pixel format
Pixel rgba2222_to_pixel(uint8_t data) {
uint8_t a = (data >> 6) & 0b11;
uint8_t b = (data >> 4) & 0b11;
uint8_t g = (data >> 2) & 0b11;
uint8_t r = data & 0b11;

// Map the 2-bit values to 8-bit color values
static const uint8_t mapping[4] = {0, 85, 170, 255};

Pixel pixel;
pixel.r = mapping[r];
pixel.g = mapping[g];
pixel.b = mapping[b];
pixel.a = mapping[a];

return pixel;
}

6 changes: 3 additions & 3 deletions video/pingo/render/texture.c
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Original file line number Diff line number Diff line change
Expand Up @@ -15,17 +15,17 @@ int texture_init( Texture *f, Vec2i size, Pixel *buf )
return 0;
}

void texture_draw(Texture *f, Vec2i pos, Pixel color)
void texture_draw(const Texture *f, Vec2i pos, Pixel color)
{
f->frameBuffer[pos.x + pos.y * f->size.x] = color;
}

Pixel texture_read(Texture *f, Vec2i pos)
Pixel texture_read(const Texture *f, Vec2i pos)
{
return f->frameBuffer[pos.x + pos.y * f->size.x];
}

Pixel texture_readF(Texture *f, Vec2f pos)
Pixel texture_readF(const Texture *f, Vec2f pos)
{
uint16_t x = (uint16_t)(pos.x * f->size.x) % f->size.x;
uint16_t y = (uint16_t)(pos.y * f->size.y) % f->size.x;
Expand Down
6 changes: 3 additions & 3 deletions video/pingo/render/texture.h
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Original file line number Diff line number Diff line change
Expand Up @@ -13,9 +13,9 @@ extern int texture_init( Texture * f, Vec2i size, Pixel *);

extern Renderable texture_as_renderable( Texture * s);

extern void texture_draw(Texture * f, Vec2i pos, Pixel color);
extern void texture_draw(const Texture * f, Vec2i pos, Pixel color);

extern Pixel texture_read(Texture * f, Vec2i pos);
extern Pixel texture_read(const Texture * f, Vec2i pos);

extern Pixel texture_readF(Texture * f, Vec2f pos);
extern Pixel texture_readF(const Texture * f, Vec2f pos);

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