near plane clipping partial

include/globals.hpp

@@ -1,8 +1,8 @@
 #ifndef DELTA_GLOBALS
 #define DELTA_GLOBALS
 
-const int SIMULATED_WIDTH = 1920;
-const int SIMULATED_HEIGHT = 1080;
+const int SIMULATED_WIDTH = 800;
+const int SIMULATED_HEIGHT = 600;
 const int FOCAL = 300;
 
 #endif

include/math.hpp

@@ -36,11 +36,25 @@ class DeltaVector3 {
 };
 
 float getDeterminant(const DeltaVector2 &pointA, const DeltaVector2 &pointB, const DeltaVector2 &candidate);
+DeltaVector2 barycentricToScreen(const DeltaVector3 &baryPoint, const DeltaVector2 &a, const DeltaVector2 &b, const DeltaVector2 &c);
+DeltaVector3 intersect(DeltaVector3 a, DeltaVector3 b, float nearZ);
 
 struct DeltaTriangle {
     DeltaVector3 a, b, c;  
 };
 
+struct DeltaTriangle2D {
+    DeltaVector2 a, b, c;  
+};
+
+
+struct DeltaRenderTriangle {
+    DeltaVector3 a, b, c;
+    DeltaVector2 uva, uvb, uvc;
+};
+
+int clipTriangleAgainstNearPlane(float nearY, const DeltaRenderTriangle &in, DeltaRenderTriangle &out1, DeltaRenderTriangle &out2);
+
 uint32_t SDLColorToUint32(SDL_Color color);
 
 #endif

include/renderer/calls.hpp

@@ -7,6 +7,6 @@
 
 void rasterizeTriangle(SDL_Renderer *renderer, const DeltaVector2 &a, const DeltaVector2 &b, const DeltaVector2 &c);
 void rasterizeTriangleFast(SDL_Surface* surface, const DeltaVector2& v0, const DeltaVector2& v1, const DeltaVector2& v2, uint32_t color);
-void rasterizeTriangleSurface(SDL_Surface* surface, const DeltaVector2& a, const DeltaVector2& b, const DeltaVector2& c, uint32_t color);
+void rasterizeTriangleSurface(SDL_Surface* surface, const DeltaVector2& v0, const DeltaVector2& v1, const DeltaVector2& v2, uint32_t color, float u0, float v0_uv, float u1, float v1_uv, float u2, float v2_uv);
 void setPixel(SDL_Surface* surface, int x, int y, uint32_t color);
 #endif

include/renderer/camera.hpp

@@ -10,7 +10,9 @@ class DeltaCamera {
 
         DeltaCamera() {pos = DeltaVector3(); angle = DeltaVector2();};
         DeltaCamera(float x, float y, float z);
+        DeltaVector3 translatePoint(const DeltaVector3 &worldPos);
         DeltaVector2 projectPointVec(const DeltaVector3 &worldPos);
+        int projectTriangle(const DeltaTriangle &in, DeltaTriangle2D &out1, DeltaTriangle2D &out2);
         DeltaVector2 projectPoint(float worldX, float worldY, float worldZ);
 };
 

src/main.cpp

@@ -6,6 +6,7 @@
 #include <string>
 #include <algorithm>
 #include <vector>
+#include <float.h>
 
 #include "globals.hpp"
 #include "math.hpp"
@@ -19,11 +20,11 @@ static SDL_Renderer *renderer = NULL;
 DeltaVector2 temp1(125, 150), temp2(150, 120), temp3(100, 100);
 DeltaVector2 topleft, bottomright, p;
 
-Player player = Player(70, 110, 20);
+Player player = Player(200, -200, 20);
 double prev = 0, now = 0, deltaTime;
 SDL_Surface* backbuffer = NULL;
 
-std::vector<DeltaTriangle> triangles;
+std::vector<DeltaRenderTriangle> triangles;
 SDL_Texture* gpuTexture = NULL;
 
 SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
@@ -36,7 +37,7 @@ SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
         return SDL_APP_FAILURE;
     }
 
-    if (!SDL_CreateWindowAndRenderer("game", SIMULATED_WIDTH, SIMULATED_HEIGHT, SDL_WINDOW_FULLSCREEN, &window, &renderer)) {
+    if (!SDL_CreateWindowAndRenderer("game", SIMULATED_WIDTH, SIMULATED_HEIGHT, 0, &window, &renderer)) {
         SDL_Log("Couldn't create window/renderer: %s", SDL_GetError());
         return SDL_APP_FAILURE;
     }
@@ -45,7 +46,8 @@ SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
 
     SDL_SetRenderLogicalPresentation(renderer, SIMULATED_WIDTH, SIMULATED_HEIGHT, SDL_LOGICAL_PRESENTATION_LETTERBOX);
 
-    triangles.push_back({ {40, 10, 0}, {40, 210, 0}, {40, 10, 200} });
+    triangles.push_back({ {40, 10, 200}, {40, 210, 0}, {40, 10, 0} , {0, 0}, {1, 1}, {0, 1}});
+    triangles.push_back({ {40, 210, 200}, {40, 210, 0}, {40, 10, 200}, {1, 0}, {1, 1}, {0, 0} });
     backbuffer = SDL_CreateSurface(SIMULATED_WIDTH, SIMULATED_HEIGHT, SDL_PIXELFORMAT_ARGB8888);
     gpuTexture = SDL_CreateTexture(
         renderer, 
@@ -55,6 +57,8 @@ SDL_AppResult SDL_AppInit(void **appstate, int argc, char *argv[])
         SIMULATED_HEIGHT
     );
 
+    SDL_SetRenderVSync(renderer, 1);
+
     return SDL_APP_CONTINUE;  /* carry on with the program! */
 }
 
@@ -101,12 +105,52 @@ SDL_AppResult SDL_AppIterate(void *appstate)
     // rendered = player.camera.projectPointVec({ 40, 210, -170 });
     // SDL_RenderPoint(renderer, rendered.x, rendered.y);
 
-    for (auto triangle : triangles) {
-        DeltaVector2 pointA = player.camera.projectPointVec(triangle.a), pointB = player.camera.projectPointVec(triangle.b), pointC = player.camera.projectPointVec(triangle.c);
-
-        rasterizeTriangleFast(backbuffer, pointA, pointB, pointC, SDLColorToUint32({ 255, 0, 255, 255 }));
+    if (SDL_MUSTLOCK(backbuffer)) {
+        SDL_LockSurface(backbuffer);
     }
 
+    DeltaTriangle triangle1, triangle2;
+    for (auto triangle : triangles) {
+        // DeltaVector2 pointA = player.camera.projectPointVec(triangle.a), pointB = player.camera.projectPointVec(triangle.b), pointC = player.camera.projectPointVec(triangle.c);
+        DeltaTriangle2D out1, out2;
+
+        int numtriangles = player.camera.projectTriangle({ triangle.a, triangle.b, triangle.c }, out1, out2);
+        // SDL_Log(std::to_string(numtriangles).c_str());
+        if (numtriangles == 1) {
+            // rasterizeTriangleFast(backbuffer, out1.a, out1.b, out1.c, SDLColorToUint32({ 255, 0, 0, 255 }));
+            // rasterizeTriangleFast(backbuffer, out1.c, out1.b, out1.a, SDLColorToUint32({ 0, 0, 255, 255 }));
+            rasterizeTriangleSurface(backbuffer, out1.a, out1.b, out1.c, SDLColorToUint32({ 0, 255, 0, 255 }), triangle.uva.x, triangle.uva.y, triangle.uvb.x, triangle.uvb.y, triangle.uvc.x, triangle.uvc.y);
+            // SDL_Log(std::to_string(triangle.a.y).c_str());
+            // SDL_Log(std::to_string(triangle.b.y).c_str());
+            // SDL_Log(std::to_string(triangle.c.y).c_str());
+        }
+        if (numtriangles == 2) {
+            // rasterizeTriangleFast(backbuffer, out1.a, out1.b, out1.c, SDLColorToUint32({ 255, 0, 0, 255 }));
+            rasterizeTriangleSurface(backbuffer, out1.a, out1.b, out1.c, SDLColorToUint32({ 0, 255, 0, 255 }), triangle.uva.x, triangle.uva.y, triangle.uvb.x, triangle.uvb.y, triangle.uvc.x, triangle.uvc.y);
+            // rasterizeTriangleFast(backbuffer, out1.c, out1.b, out1.a, SDLColorToUint32({ 0, 255, 0, 255 }));
+            rasterizeTriangleSurface(backbuffer, out2.a, out2.b, out2.c, SDLColorToUint32({ 0, 255, 0, 255 }), triangle.uva.x, triangle.uva.y, triangle.uvb.x, triangle.uvb.y, triangle.uvc.x, triangle.uvc.y);
+        }
+
+        // int intersected = clipTriangleAgainstNearPlane(0.1, { triangle.a, triangle.b, triangle.c }, triangle1, triangle2);
+
+        // rasterizeTriangleFast(backbuffer, pointA, pointB, pointC, SDLColorToUint32({ 255, 0, 0, 255 }));
+        // if (intersected == 0) continue;
+
+        // rasterizeTriangleFast(backbuffer, pointA, pointB, pointC, SDLColorToUint32({ 255, 0, 0, 255 }));
+        // SDL_Log("===");
+    }
+    SDL_Log("=====");
+
+    if (SDL_MUSTLOCK(backbuffer)) {
+        SDL_UnlockSurface(backbuffer);
+    }
+
+    // for (int y = 0; y < SIMULATED_HEIGHT; y++) {
+    //     for (int x = 0; x < SIMULATED_WIDTH; x++) {
+    //         setPixel(backbuffer, x, y, SDLColorToUint32({ 255, 0, 0 }));
+    //     }
+    // }
+
     SDL_UpdateTexture(gpuTexture, NULL, backbuffer->pixels, backbuffer->pitch);
     
     SDL_SetRenderDrawColor(renderer, 255, 0, 0, 255);

src/math.cpp

@@ -1,5 +1,6 @@
 #include <SDL3/SDL.h>
 #include <cmath>
+#include <float.h>
 
 #include "math.hpp"
 
@@ -112,7 +113,105 @@ float getDeterminant(const DeltaVector2 &pointA, const DeltaVector2 &pointB, con
     return (ab.y * ac.x) - (ab.x * ac.y);
 }
 
+DeltaVector2 barycentricToScreen(const DeltaVector3 &baryPoint, const DeltaVector2 &a, const DeltaVector2 &b, const DeltaVector2 &c) {
+    return {(baryPoint.x * a.x) + (baryPoint.y * b.x) + (baryPoint.z * c.x),(baryPoint.x * a.y) + (baryPoint.y * b.y) + (baryPoint.z * c.y)};
+}
+
 uint32_t SDLColorToUint32(SDL_Color color) {
     // Layout: AAAAAAAA RRRRRRRR GGGGGGGG BBBBBBBB
     return (uint32_t)((color.a << 24) | (color.r << 16) | (color.g << 8) | (color.b << 0));
+}
+
+DeltaVector3 intersect(DeltaVector3 a, DeltaVector3 b, float nearZ) {
+    if (std::abs(b.y - a.y) < 0.0001f) {
+        SDL_Log("IMAGINEEEE");
+        return a;
+    }
+
+    float t = (nearZ - a.y) / (b.y - a.y);
+    return DeltaVector3(
+        a.x + t * (b.x - a.x),
+        nearZ,
+        a.z + t * (b.z - a.z)
+    );
+}
+
+int clipTriangleAgainstNearPlane(float nearY, const DeltaRenderTriangle &in, DeltaRenderTriangle &out1, DeltaRenderTriangle &out2) {
+    // DeltaVector3 inside[3], outside[3];
+    // DeltaVector3 cur;
+    // int nIn = 0, nOut = 0;
+
+    // for (int i = 0; i < 3; i++) {
+    //     if (i == 0) cur = in.a;
+    //     else if (i == 1) cur = in.b;
+    //     else cur = in.c;
+    //     if (cur.y > 0.1f) inside[nIn++] = cur;
+    //     else outside[nOut++] = cur;
+    // }
+
+    // if (nIn == 0) return 0;
+    // if (nIn == 3) { out1 = in; return 1; }
+
+    // if (nIn == 1) {
+    //     out1.c = inside[0];
+    //     out1.b = intersect(inside[0], outside[0], nearZ);
+    //     out1.a = intersect(inside[0], outside[1], nearZ);
+    //     return 1;
+    // }
+
+    // if (nIn == 2) {
+    //     out1.a = inside[0];
+    //     out1.b = inside[1];
+    //     out1.c = intersect(inside[1], outside[0], nearZ);
+
+    //     out2.a = inside[0];
+    //     out2.b = out1.a;
+    //     out2.c = intersect(outside[0], inside[0], nearZ);
+        
+    //     return 2;
+    // }
+
+    const DeltaVector3* v[3] = { &in.a, &in.b, &in.c };
+    bool inside[3];
+    int insideCount = 0;
+
+    for (int i = 0; i < 3; i++) {
+        inside[i] = (v[i]->y >= nearY);
+        if (inside[i]) insideCount++;
+    }
+
+    if (insideCount == 0) return 0;
+    if (insideCount == 3) { out1 = in; return 1; }
+
+    if (insideCount == 1) {
+        // Find the one vertex that is inside
+        int i0 = (inside[0]) ? 0 : (inside[1] ? 1 : 2);
+        int i1 = (i0 + 1) % 3;
+        int i2 = (i0 + 2) % 3;
+
+        out1.a = *v[i0];
+        out1.b = intersect(*v[i0], *v[i1], nearY);
+        out1.c = intersect(*v[i0], *v[i2], nearY);
+        return 1;
+    }
+
+    if (insideCount == 2) {
+        // Find the one vertex that is OUTSIDE
+        int i0 = (!inside[0]) ? 0 : (!inside[1] ? 1 : 2);
+        int i1 = (i0 + 1) % 3; // Inside vertex 1
+        int i2 = (i0 + 2) % 3; // Inside vertex 2
+
+        // Triangle 1: Connects the two inside vertices and one intersection
+        out1.a = *v[i1];
+        out1.b = *v[i2];
+        out1.c = intersect(*v[i2], *v[i0], nearY);
+
+        // Triangle 2: Connects the first inside vertex and the two intersections
+        out2.a = *v[i1];
+        out2.b = out1.c;
+        out2.c = intersect(*v[i0], *v[i1], nearY);
+        return 2;
+    }
+
+    return 0;
 }

src/player.cpp

@@ -36,6 +36,7 @@ void Player::update(float deltaTime) {
     // SDL_Log(std::to_string(pos.x).c_str());
     // SDL_Log(std::to_string(pos.y).c_str());
     // SDL_Log(std::to_string(pos.z).c_str());
+    // SDL_Log("===");
 
     angle.x += angleChange.x * 3.14 * deltaTime;
     angle.y += angleChange.y * 3.14 * deltaTime;

src/renderer/calls.cpp

@@ -9,37 +9,71 @@ void setPixel(SDL_Surface* surface, int x, int y, uint32_t color) {
     // 1. Boundary check to prevent memory corruption (Crashes)
     if (x < 0 || x >= surface->w || y < 0 || y >= surface->h) return;
 
-    // 2. Lock the surface if it requires it (usually for hardware surfaces)
-    if (SDL_MUSTLOCK(surface)) {
-        SDL_LockSurface(surface);
-    }
-
     // 3. Calculate the pointer to the specific pixel
     // We cast to uint8_t* to do byte-math, then to uint32_t* to write the color
     uint8_t* pixel_ptr = (uint8_t*)surface->pixels + (y * surface->pitch) + (x * sizeof(uint32_t));
     *(uint32_t*)pixel_ptr = color;
-
-    if (SDL_MUSTLOCK(surface)) {
-        SDL_UnlockSurface(surface);
-    }
 }
 
-void rasterizeTriangleSurface(SDL_Surface* surface, const DeltaVector2& a, const DeltaVector2& b, const DeltaVector2& c, uint32_t color) {
-    DeltaVector2 begin, end, p;
-    begin.x = std::min(a.x, std::min(b.x, c.x));
-    begin.y = std::min(a.y, std::min(b.y, c.y));
-    end.x = std::max(a.x, std::max(b.x, c.x));
-    end.y = std::max(a.y, std::max(b.y, c.y));
+void rasterizeTriangleSurface(SDL_Surface* surface, const DeltaVector2& v0, const DeltaVector2& v1, const DeltaVector2& v2, uint32_t color, float u0, float v0_uv, float u1, float v1_uv, float u2, float v2_uv) {
+    int minX = std::max(0, (int)std::min({v0.x, v1.x, v2.x}));
+    int maxX = std::min((int)surface->w - 1, (int)std::max({v0.x, v1.x, v2.x}));
+    int minY = std::max(0, (int)std::min({v0.y, v1.y, v2.y}));
+    int maxY = std::min((int)surface->h - 1, (int)std::max({v0.y, v1.y, v2.y}));
 
-    for (int y = begin.y; y < end.y; y++) {
-        for (int x = begin.x; x < end.x; x++) {
-            p.x = x; p.y = y;
-            
-            if (getDeterminant(a, b, p) >= 0 && getDeterminant(b, c, p) >= 0 && getDeterminant(c, a, p) >= 0) {
-                setPixel(surface, x, y, color);
+    // precompute edge coefficients
+    // edge function: E(x, y) = (v_i.y - v_j.y)x + (v_j.x - v_i.x)y + (v_i.x * v_j.y - v_j.x * v_i.y)
+    float a0 = v1.y - v2.y, b0 = v2.x - v1.x, c0 = v1.x * v2.y - v2.x * v1.y;
+    float a1 = v2.y - v0.y, b1 = v0.x - v2.x, c1 = v2.x * v0.y - v0.x * v2.y;
+    float a2 = v0.y - v1.y, b2 = v1.x - v0.x, c2 = v0.x * v1.y - v1.x * v0.y;
+
+    // calculate initial values at (minX, minY)
+    float e0_row = a0 * minX + b0 * minY + c0;
+    float e1_row = a1 * minX + b1 * minY + c1;
+    float e2_row = a2 * minX + b2 * minY + c2;
+
+    float area = a0 * v0.x + b0 * v0.y + c0;
+    if (std::abs(area) < 0.0001f) return;
+    float invArea = 1.0f / area;
+
+    uint32_t* pixels = (uint32_t*)surface->pixels;
+    int pitch = surface->pitch / sizeof(uint32_t);
+
+    // main raster loop
+    for (int y = minY; y <= maxY; y++) {
+        float e0 = e0_row;
+        float e1 = e1_row;
+        float e2 = e2_row;
+        
+        uint32_t* rowPtr = &pixels[y * pitch];
+
+        for (int x = minX; x <= maxX; x++) {
+            // only fill if pixel is inside all 3 edges
+            if (e0 >= 0 && e1 >= 0 && e2 >= 0) {
+                float w0 = e0 * invArea;
+                float w1 = e1 * invArea;
+                float w2 = e2 * invArea;
+
+                float u = w0 * u0 + w1 * u1 + w2 * u2;
+                float v = w0 * v0_uv + w1 * v1_uv + w2 * v2_uv;
+
+                uint8_t r = (uint8_t)(u * 255.0f);
+                uint8_t g = (uint8_t)(v * 255.0f);
+                uint8_t b = 128;
+
+                rowPtr[x] = (255 << 24) | (r << 16) | (g << 8) | b;
             }
-
+            
+            // step horizontally: just 3 additions
+            e0 += a0;
+            e1 += a1;
+            e2 += a2;
         }
+
+        // step vertically: update the row starts
+        e0_row += b0;
+        e1_row += b1;
+        e2_row += b2;
     }
 }
 

src/renderer/camera.cpp

@@ -3,10 +3,11 @@
 // please, dont. if you do continue, edit the value below
 // as a warning for future you.
 
-// hoursWasted = 5
+// hoursWasted = 8
 
 #include <SDL3/SDL.h>
 #include <cmath>
+#include <float.h>
 
 #include "renderer/camera.hpp"
 #include "globals.hpp"
@@ -16,8 +17,8 @@ DeltaCamera::DeltaCamera(float x, float y, float z) {
     angle = DeltaVector2();
 }
 
-DeltaVector2 DeltaCamera::projectPointVec(const DeltaVector3 &worldPos) {
-    DeltaVector3 calculatedPos; DeltaVector2 projected;
+DeltaVector3 DeltaCamera::translatePoint(const DeltaVector3 &worldPos) {
+    DeltaVector3 calculatedPos;
     float sineX = std::sin(angle.x);
     float cosineX = std::cos(angle.x);
 
@@ -39,11 +40,23 @@ DeltaVector2 DeltaCamera::projectPointVec(const DeltaVector3 &worldPos) {
     calculatedPos.z = t.z * cosineY + ry * sineY;
     // dont touch calculatedPos.x
 
-    // calculatedPos.y = calculatedPos.y * cosineY;
+    // if (calculatedPos.y <= 0.1f) return {-FLT_MAX, 0, 0};
+
+    return calculatedPos;
+}
+
+DeltaVector2 DeltaCamera::projectPointVec(const DeltaVector3 &worldPos) {
+    DeltaVector3 calculatedPos; DeltaVector2 projected;
+    calculatedPos = worldPos; 
+
+    // calculatedPos.y += 0.00001f;
 
     projected.x = calculatedPos.x * FOCAL / calculatedPos.y + SIMULATED_WIDTH / 2.0f;
     projected.y = calculatedPos.z * FOCAL / calculatedPos.y + SIMULATED_HEIGHT / 2.0f;
 
+    // projected.x = std::min((float)SIMULATED_WIDTH, std::max(0.0f, projected.x));
+    // projected.x = std::min((float)SIMULATED_HEIGHT, std::max(0.0f, projected.y));
+
     // now gotta convert y to our y
     projected.y = SIMULATED_HEIGHT - projected.y;
 
@@ -51,6 +64,33 @@ DeltaVector2 DeltaCamera::projectPointVec(const DeltaVector3 &worldPos) {
     return projected;
 }
 
+int DeltaCamera::projectTriangle(const DeltaTriangle &in, DeltaTriangle2D &out1, DeltaTriangle2D &out2) {
+    DeltaTriangle translated = { translatePoint(in.a), translatePoint(in.b), translatePoint(in.c) }, clipped1, clipped2;
+
+    int numClipped = clipTriangleAgainstNearPlane(0.01, translated, clipped1, clipped2);
+    if (numClipped == 1) {
+        out1.a = projectPointVec(clipped1.a);
+        out1.b = projectPointVec(clipped1.b);
+        out1.c = projectPointVec(clipped1.c);
+
+        // out1.a = projectPointVec(translated.a);
+        // out1.b = projectPointVec(translated.b);
+        // out1.c = projectPointVec(translated.c);
+    }
+
+    if (numClipped == 2) {
+
+        out1.a = projectPointVec(clipped1.a);
+        out1.b = projectPointVec(clipped1.b);
+        out1.c = projectPointVec(clipped1.c);
+
+        out2.a = projectPointVec(clipped2.a);
+        out2.b = projectPointVec(clipped2.b);
+        out2.c = projectPointVec(clipped2.c);
+    }
+    return numClipped;
+}
+
 DeltaVector2 DeltaCamera::projectPoint(float worldX, float worldY, float worldZ) {
     // simple conversion, dont iterate further
     return projectPointVec({ worldX, worldY, worldZ });