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added gradient shaders to triangle primative

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This commit is contained in:
Annika
2026-07-08 15:08:48 -07:00
parent f61e3a8237
commit 27b7640c85
4 changed files with 112 additions and 82 deletions
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primatives/triangle.cpp
+108 -70
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@@ -1,6 +1,7 @@
#pragma once
#include <stdint.h>
#include <algorithm>
#include "../datatypes.cpp"
#include "../helpers.cpp"
@@ -9,7 +10,6 @@
namespace UwU {
class Triangle {
private:
public:
Triangle(uint16_t x0, uint16_t y0, uint16_t x1, uint16_t y1, uint16_t x2, uint16_t y2) {
@@ -29,95 +29,133 @@ namespace UwU {
uint16_t y2;
// Draw a triangle
void draw (Buffer buffer, Color color) {
Coord2 top = Coord2();
Coord2 mid = Coord2();
Coord2 btm = Coord2();
// cases: left-handed, right-handed
void draw (Buffer buffer, Shader shader) {
uint16_t topX, topY, midX, midY, btmX, btmY;
// Find top, middle and bottom points of triangle
if (y0 <= y1 && y0 <= y2) {
top.x = x0;
top.y = y0;
topX = x0;
topY = y0;
if (y1 < y2) {
mid.x = x1;
mid.y = y1;
btm.x = x2;
btm.y = y2;
midX = x1;
midY = y1;
btmX = x2;
btmY = y2;
} else {
mid.x = x2;
mid.y = y2;
btm.x = x1;
btm.y = y1;
midX = x2;
midY = y2;
btmX = x1;
btmY = y1;
}
} else if (y1 <= y0 && y1 <= y2) {
top.x = x1;
top.y = y1;
topX = x1;
topY = y1;
if (y0 < y2) {
mid.x = x0;
mid.y = y0;
btm.x = x2;
btm.y = y2;
midX = x0;
midY = y0;
btmX = x2;
btmY = y2;
} else {
mid.x = x2;
mid.y = y2;
btm.x = x0;
btm.y = y0;
midX = x2;
midY = y2;
btmX = x0;
btmY = y0;
}
} else {
top.x = x2;
top.y = y2;
topX = x2;
topY = y2;
if (y0 < y1) {
mid.y = y0;
mid.x = x0;
btm.x = x1;
btm.y = y1;
midY = y0;
midX = x0;
btmX = x1;
btmY = y1;
} else {
mid.x = x1;
mid.y = y1;
btm.x = x0;
btm.y = y0;
midX = x1;
midY = y1;
btmX = x0;
btmY = y0;
}
}
// printf("top: (%u, %u)\n", top.x, top.y);
// printf("mid: (%u, %u)\n", mid.x, mid.y);
// printf("btm: (%u, %u)\n", btm.x, btm.y);
uint16_t height = 1 + btm.y - top.y;
uint16_t height = 1 + btmY - topY;
int16_t longBound[height];
int16_t splitBound[height];
// int16_t rightBound[height];
Helpers::bresenham(0, top.x, height - 1, btm.x, longBound);
// printf("longBound\n");
if ((int16_t)mid.x < longBound[mid.y - top.y]) {
// left-handed triangle
// printf("left-handed\n");
// rightBound = longBound;
Helpers::bresenham(0, top.x, mid.y - top.y, mid.x, splitBound);
// printf("splitTop\n");
Helpers::bresenham(mid.y - top.y, mid.x, height - 1, btm.x, splitBound);
// printf("splitBtm\n");
// for (uint16_t i = 0; i < height; i++) {
// printf("(%u, %u)\n", i, splitBound[i]);
// }
for (uint16_t i = 0; i < height; i++) {
for (uint16_t x = (uint16_t)splitBound[i]; x <= (uint16_t)longBound[i]; x++) {
// Helpers::putPixel(buffer, x, i + (uint32_t)top.y, color.r, color.g, color.b, color.a);
buffer.drawPixel(x, i + (uint16_t)top.y, color);
// Calculate LUT for longest vertical line (from top to bottom)
Helpers::bresenham(0, topX, height - 1, btmX, longBound);
// Calculate LUT for short two lines
Helpers::bresenham(0, topX, midY - topY, midX, splitBound);
Helpers::bresenham(midY - topY, midX, height - 1, btmX, splitBound);
if (shader.shaderType == COLOR) {
// Left-handed triangle case (midpoint is left of triangle)
if ((int16_t)midX < longBound[midY - topY]) {
for (uint16_t i = 0; i < height; i++) {
for (uint16_t x = (uint16_t)splitBound[i]; x <= (uint16_t)longBound[i]; x++) {
buffer.drawPixel(x, i + (uint16_t)topY, shader.c0);
}
}
// Right-handed triangle case (midpoint is right of triangle)
} else {
for (uint16_t i = 0; i < height; i++) {
for (uint16_t x = (uint16_t)longBound[i]; x <= (uint16_t)splitBound[i]; x++) {
buffer.drawPixel(x, i + (uint16_t)topY, shader.c0);
}
}
}
} else {
// right-handed triangle
// printf("right-handed\n");
// leftBound = longBound;
Helpers::bresenham(0, top.x, mid.y - top.y, mid.x, splitBound);
// printf("splitTop\n");
Helpers::bresenham(mid.y - top.y, mid.x, height - 1, btm.x, splitBound);
// printf("splitBtm\n");
for (uint16_t i = 0; i < height; i++) {
for (uint16_t x = (uint16_t)longBound[i]; x <= (uint16_t)splitBound[i]; x++) {
// Helpers::putPixel(buffer, x, i + (uint32_t)top.y, color.r, color.g, color.b, color.a);
buffer.drawPixel(x, i + (uint16_t)top.y, color);
return;
} else if (shader.shaderType == HGRADIENT) {
// find left and right bounds
uint16_t leftmost = std::min(x0, std::min(x1, x2));
uint16_t rightmost = std::max(x0, std::max(x1, x2));
// precompute gradient LUT
Color cols[rightmost - leftmost];
for (uint16_t x = leftmost; x < rightmost; x++) {
cols[x - leftmost] = ShaderMethods::gradient(shader.u0, shader.scale, shader.c0, shader.c1, x);
}
// Left-handed triangle case (midpoint is left of triangle)
if ((int16_t)midX < longBound[midY - topY]) {
for (uint16_t i = 0; i < height; i++) {
for (uint16_t x = (uint16_t)splitBound[i]; x <= (uint16_t)longBound[i]; x++) {
buffer.drawPixel(x, i + (uint16_t)topY, cols[x - leftmost]);
}
}
// Right-handed triangle case (midpoint is right of triangle)
} else {
for (uint16_t i = 0; i < height; i++) {
for (uint16_t x = (uint16_t)longBound[i]; x <= (uint16_t)splitBound[i]; x++) {
buffer.drawPixel(x, i + (uint16_t)topY, cols[x - leftmost]);
}
}
}
return;
} else if (shader.shaderType == VGRADIENT) {
Color c;
// Left-handed triangle case (midpoint is left of triangle)
if ((int16_t)midX < longBound[midY - topY]) {
for (uint16_t i = 0; i < height; i++) {
c = ShaderMethods::gradient(shader.v0, shader.scale, shader.c0, shader.c1, i + topY);
for (uint16_t x = (uint16_t)splitBound[i]; x <= (uint16_t)longBound[i]; x++) {
buffer.drawPixel(x, i + (uint16_t)topY, c);
}
}
// Right-handed triangle case (midpoint is right of triangle)
} else {
for (uint16_t i = 0; i < height; i++) {
c = ShaderMethods::gradient(shader.v0, shader.scale, shader.c0, shader.c1, i + topY);
for (uint16_t x = (uint16_t)longBound[i]; x <= (uint16_t)splitBound[i]; x++) {
buffer.drawPixel(x, i + (uint16_t)topY, c);
}
}
}
return;
}
return;
}