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Premultiplied alpha and gamma corrct!

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This commit is contained in:
Krzosa Karol
2022-02-20 19:55:56 +01:00
parent 8cfd52ed81
commit a5b111d24a
4 changed files with 74 additions and 37 deletions
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graphics3.rdbg
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81
main.cpp
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@@ -39,8 +39,10 @@ OK Reading OBJ files
* *
*/ */
#define OS_WINDOWS 1 #define OS_WINDOWS 1
#define BILINEAR_BLEND 1
#define PERSPECTIVE_CORRECT_INTERPOLATION 1 #define PERSPECTIVE_CORRECT_INTERPOLATION 1
#define BILINEAR_BLEND 1
#define GAMMA_CORRECT_BLENDING 1
#define PREMULTIPLIED_ALPHA_BLENDING 1
#define _CRT_SECURE_NO_WARNINGS #define _CRT_SECURE_NO_WARNINGS
#include "main.h" #include "main.h"
@@ -53,7 +55,6 @@ OK Reading OBJ files
GLOBAL OS os = {}; GLOBAL OS os = {};
GLOBAL bool draw_rects = 0; GLOBAL bool draw_rects = 0;
GLOBAL bool draw_wireframe = 0; GLOBAL bool draw_wireframe = 0;
#include "rasterization_feature_selection.cpp"
struct Face { struct Face {
int p[3]; int p[3];
@@ -124,7 +125,6 @@ void draw_bitmap(Image* dst, Image* src, Vec2 pos) {
miny = 0; miny = 0;
} }
for (I64 y = miny; y < maxy; y++) { for (I64 y = miny; y < maxy; y++) {
for (I64 x = minx; x < maxx; x++) { for (I64 x = minx; x < maxx; x++) {
I64 tx = x - minx + offsetx; I64 tx = x - minx + offsetx;
@@ -198,26 +198,43 @@ void draw_triangle(Image* dst, float *depth_buffer, Image *src,
float udiff = u - (float)ui; float udiff = u - (float)ui;
float vdiff = v - (float)vi; float vdiff = v - (float)vi;
// Origin UV (0,0) is in bottom left // Origin UV (0,0) is in bottom left
U32* pixel = src->pixels + (ui + (src->y - 1ll - vi) * src->x); U32 *pixel = src->pixels + (ui + (src->y - 1ll - vi) * src->x);
U32 *dst_pixel = dst->pixels + (x + y * dst->x);
#if BILINEAR_BLEND #if BILINEAR_BLEND
Vec4 pixelx1y1 = srgb_to_almost_linear(v4abgr(*pixel)); Vec4 pixelx1y1 = vec4abgr(*pixel);
Vec4 pixelx2y1 = srgb_to_almost_linear(v4abgr(*(pixel + 1))); Vec4 pixelx2y1 = vec4abgr(*(pixel + 1));
Vec4 pixelx1y2 = srgb_to_almost_linear(v4abgr(*(pixel - src->x))); Vec4 pixelx1y2 = vec4abgr(*(pixel - src->x));
Vec4 pixelx2y2 = srgb_to_almost_linear(v4abgr(*(pixel + 1 - src->x))); Vec4 pixelx2y2 = vec4abgr(*(pixel + 1 - src->x));
#if GAMMA_CORRECT_BLENDING
pixelx1y1 = srgb_to_almost_linear(pixelx1y1);
pixelx2y1 = srgb_to_almost_linear(pixelx2y1);
pixelx1y2 = srgb_to_almost_linear(pixelx1y2);
pixelx2y2 = srgb_to_almost_linear(pixelx2y2);
#endif // GAMMA_CORRECT_BLENDING
Vec4 blendx1 = lerp(pixelx1y1, pixelx2y1, udiff); Vec4 blendx1 = lerp(pixelx1y1, pixelx2y1, udiff);
Vec4 blendx2 = lerp(pixelx1y2, pixelx2y2, udiff); Vec4 blendx2 = lerp(pixelx1y2, pixelx2y2, udiff);
Vec4 result_color = lerp(blendx1, blendx2, vdiff); Vec4 result_color = lerp(blendx1, blendx2, vdiff);
#if PREMULTIPLIED_ALPHA_BLENDING
Vec4 dst_color = vec4abgr(*dst_pixel);
#if GAMMA_CORRECT_BLENDING
dst_color = srgb_to_almost_linear(dst_color);
#endif
result_color.r = result_color.r + (1-result_color.a) * dst_color.r;
result_color.g = result_color.g + (1-result_color.a) * dst_color.g;
result_color.b = result_color.b + (1-result_color.a) * dst_color.b;
result_color.a = result_color.a + dst_color.a - result_color.a*dst_color.a;
#endif // PREMULTIPLIED_ALPHA_BLENDING
#if GAMMA_CORRECT_BLENDING
result_color = almost_linear_to_srgb(result_color); result_color = almost_linear_to_srgb(result_color);
ASSERT(result_color.r <= 1 && result_color.g <= 1 && result_color.b <= 1); ASSERT(result_color.r <= 1 && result_color.g <= 1 && result_color.b <= 1);
#endif // GAMMA_CORRECT_BLENDING
U32 color32 = color_to_u32abgr(result_color); U32 color32 = color_to_u32abgr(result_color);
#else #else // BILINEAR_BLEND
U32 color32 = *pixel; U32 color32 = *pixel;
#endif #endif // BILINEAR_BLEND
dst->pixels[x + y * dst->x] = color32; *dst_pixel = color32;
} }
} }
} }
@@ -228,7 +245,6 @@ void draw_triangle(Image* dst, float *depth_buffer, Image *src,
draw_rect(dst, p2.x-4, p2.y-4, 8,8, 0x000000ff); draw_rect(dst, p2.x-4, p2.y-4, 8,8, 0x000000ff);
} }
} }
#include "raster_functions.cpp"
FUNCTION FUNCTION
void draw_line(Image *dst, float x0, float y0, float x1, float y1) { void draw_line(Image *dst, float x0, float y0, float x1, float y1) {
@@ -268,13 +284,24 @@ Image load_image(const char* path) {
int x, y, n; int x, y, n;
unsigned char* data = stbi_load(path, &x, &y, &n, 4); unsigned char* data = stbi_load(path, &x, &y, &n, 4);
Image result = { (U32*)data, x, y }; Image result = { (U32*)data, x, y };
#if PREMULTIPLIED_ALPHA_BLENDING
U32 *p = result.pixels;
for (int Y = 0; Y < y; Y++) {
for (int X = 0; X < x; X++) {
Vec4 color = vec4abgr(*p);
color.r *= color.a;
color.g *= color.a;
color.b *= color.a;
*p++ = color_to_u32abgr(color);
}
}
#endif
return result; return result;
} }
int main() { int main() {
obj::test(); obj::test();
os.init({ 1280,720 }); os.init({ 1280,720 });
generate_stuff();
float rotation = 0; float rotation = 0;
Vec3 camera_pos = {0,0,-5}; Vec3 camera_pos = {0,0,-5};
@@ -287,14 +314,16 @@ int main() {
Image img = load_image("assets/bricksx64.png"); Image img = load_image("assets/bricksx64.png");
Image screen320 = {(U32 *)malloc(320*180*sizeof(U32)), 320, 180}; int screen_x = 320;
float* depth320 = (float *)malloc(sizeof(float) * 320 * 180); int screen_y = 60;
Image screen320 = {(U32 *)malloc(screen_x*screen_y*sizeof(U32)), screen_x, screen_y};
float* depth320 = (float *)malloc(sizeof(float) * screen_x * screen_y);
while (os.game_loop()) { while (os.game_loop()) {
Mat4 perspective = make_matrix_perspective(60.f, (float)os.screen.x, (float)os.screen.y, 0.1f, 100.f); Mat4 perspective = make_matrix_perspective(60.f, (float)os.screen.x, (float)os.screen.y, 0.1f, 100.f);
U32* p = screen320.pixels; U32* p = screen320.pixels;
for (int y = 0; y < screen320.y; y++) { for (int y = 0; y < screen320.y; y++) {
for (int x = 0; x < screen320.x; x++) { for (int x = 0; x < screen320.x; x++) {
*p++ = 0; *p++ = 0x44444444;
} }
} }
float* dp = depth320; float* dp = depth320;
@@ -303,7 +332,7 @@ int main() {
*dp++ = -FLT_MAX; *dp++ = -FLT_MAX;
} }
} }
draw_bitmap(&screen320, &img, {0,0}); //draw_bitmap(&screen320, &img, {0,0});
Mat4 transform = make_matrix_rotation_z(rotation); Mat4 transform = make_matrix_rotation_z(rotation);
transform = transform * make_matrix_rotation_x(rotation); transform = transform * make_matrix_rotation_x(rotation);
if (os.keydown_a) rotation += 0.05f; if (os.keydown_a) rotation += 0.05f;
@@ -344,18 +373,16 @@ int main() {
//@Note: To pixel space //@Note: To pixel space
pos[j].x *= screen320.x / 2; pos[j].x *= screen320.x / 2;
pos[j].y *= screen320.y / 2; pos[j].y *= screen320.y / 2;
//pos[j].x += screen320.x / 2; pos[j].x += screen320.x / 2;
//pos[j].y += screen320.y / 2; pos[j].y += screen320.y / 2;
pos[j].x += screen320.x / 4;
pos[j].y += screen320.y / 4;
} }
draw_triangle_PERSPECTIVE_CORRECT_INTERPOLATION_on_BILINEAR_BLEND_off(&screen320, depth320, &img, pos[0], pos[1], pos[2], tex[0], tex[1], tex[2]); draw_triangle(&screen320, depth320, &img, pos[0], pos[1], pos[2], tex[0], tex[1], tex[2]);
for (int j = 0; j < 3; j++) { for (int j = 0; j < 3; j++) {
pos[j].x += screen320.x / 3; pos[j].x += screen320.x / 8;
pos[j].y += screen320.y / 3; pos[j].y += screen320.y / 8;
} }
draw_triangle_PERSPECTIVE_CORRECT_INTERPOLATION_on_BILINEAR_BLEND_on(&screen320, depth320, &img, pos[0], pos[1], pos[2], tex[0], tex[1], tex[2]); draw_triangle(&screen320, depth320, &img, pos[0], pos[1], pos[2], tex[0], tex[1], tex[2]);
if (draw_wireframe) { if (draw_wireframe) {
draw_line(&screen320, pos[0].x, pos[0].y, pos[1].x, pos[1].y); draw_line(&screen320, pos[0].x, pos[0].y, pos[1].x, pos[1].y);
draw_line(&screen320, pos[1].x, pos[1].y, pos[2].x, pos[2].y); draw_line(&screen320, pos[1].x, pos[1].y, pos[2].x, pos[2].y);

4
math.h
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@@ -290,7 +290,7 @@ Vec4 v4argb(U32 c) {
} }
FUNCTION FUNCTION
Vec4 v4abgr(U32 c) { Vec4 vec4abgr(U32 c) {
float a = ((c & 0xff000000) >> 24) / 255.f; float a = ((c & 0xff000000) >> 24) / 255.f;
float b = ((c & 0x00ff0000) >> 16) / 255.f; float b = ((c & 0x00ff0000) >> 16) / 255.f;
float g = ((c & 0x0000ff00) >> 8) / 255.f; float g = ((c & 0x0000ff00) >> 8) / 255.f;
@@ -301,7 +301,7 @@ Vec4 v4abgr(U32 c) {
FUNCTION FUNCTION
float lerp(float a, float b, float t) { float lerp(float a, float b, float t) {
float result = (1.0f - t) * a + t * b; float result = a + (b-a)*t; //(1.0f - t) * a + t * b;
return result; return result;
} }

26
raster_functions.cpp
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@@ -101,11 +101,16 @@ FUNCTION void draw_triangle_PERSPECTIVE_CORRECT_INTERPOLATION_on_BILINEAR_BLEND_
} }
if (draw_rects) { if (draw_rects) {
draw_rect(dst, p0.x-4, p0.y-4, 8,8, 0x00ff0000); draw_rect(dst, p0.x-4, p0.y-4, 8,8, 0x00ff0000);
draw_rect(dst, p1.x-4, p1.y-4, 8,8, 0x0000ff00);
draw_rect(dst, p2.x-4, p2.y-4, 8,8, 0x000000ff);
}
} }
FUNCTION void draw_triangle_PERSPECTIVE_CORRECT_INTERPOLATION_on_BILINEAR_BLEND_on (Image* dst, float *depth_buffer, Image *src, FUNCTION void draw_triangle_PERSPECTIVE_CORRECT_INTERPOLATION_on_BILINEAR_BLEND_on (Image* dst, float *depth_buffer, Image *src,
@@ -169,11 +174,16 @@ FUNCTION void draw_triangle_PERSPECTIVE_CORRECT_INTERPOLATION_off_BILINEAR_BLEND
// @Note: We could do: interpolated_z = 1.f / interpolated_z to get proper depth // @Note: We could do: interpolated_z = 1.f / interpolated_z to get proper depth
// but why waste an instruction, the smaller the depth value the farther the object
float* depth = depth_buffer + (x + y * dst->x);
// @Note: We could do: interpolated_z = 1.f / interpolated_z to get proper depth
if (*depth < interpolated_z) {
*depth = interpolated_z;
u = u * (src->x - 2);
v = v * (src->y - 2); v = v * (src->y - 2);
I64 ui = (I64)(u); I64 ui = (I64)(u);