绘制三角形

src/CMakeLists.txt

@@ -1,3 +1,6 @@
+add_executable(draw_triangle draw_triangle.cc ${commom_src})
+target_link_libraries (draw_triangle ${FC_DEP_LIBS})
+
 add_executable(draw_rect draw_rect.cc ${commom_src})
 target_link_libraries (draw_rect ${FC_DEP_LIBS})
 

src/Raster.cc

@@ -154,6 +154,105 @@ void Raster::drawLine(float2 p1, float2 p2, Rgba color1, Rgba color2) {
 
 }
 
+/**
+ * 画一条平行于x轴的直线
+ * @param span
+ */
+void Raster::drawSpan(const Span &span) {
+    //float length = tmax<int>(span.xStart - span.xEnd, 1); //取保length不为0
+
+    Rgba color;
+    float length = span.xEnd - span.xStart;
+    for (int i = span.xStart; i <= span.xEnd; i++) {
+        color = colorLerp(span.color1, span.color2, (float) (i - span.xStart) / length);
+        setPixel(i, span.y, color);
+    }
+}
+
+void Raster::drawEge(const Ege& e1, const Ege& e2) {
+
+    float xOffset1 = fabs(e1.x2 - e1.x1);
+    float yOffset1 = fabs(e1.y2 - e1.y1);
+    float setp1 = 1 / yOffset1;
+    float scale1 = (e1.y2 - e2.y2) / yOffset1; //TODO:yOffset1 不能为0
+
+    float xOffset2 = fabs(e2.x2 - e2.x1);
+    float yOffset2 = fabs(e2.y2 - e2.y1);
+    float setp2 = 1 / yOffset2; //TODO:yOffset2 不能为0
+    float scale2 = 0;
+
+
+    //优化2 不画三角形坐标y以为的部分
+//    int startY = tmin<int>(e2.y2, _height);
+//    int endY = tmax<int>(e2.y1, 0);
+//    scale2 = (startY - _height) / yOffset2;
+
+
+
+    Rgba colorE1;
+    Rgba colorE2;
+    for (int y = e2.y2; y > e2.y1; y--) {
+
+        int x2;
+        if (e2.x2 < e2.x1) {
+            x2 = e2.x2 + xOffset2 * scale2;
+        } else {
+            x2 = e2.x2 - xOffset2 * scale2;
+        }
+        colorE2 = colorLerp(e2.color2, e2.color1, scale2);
+        scale2 += setp2;
+        //setPixel(x2, y, e2.color2);
+
+
+        int x1;
+        if (e1.x2 < e1.x1) {
+            x1 = e1.x2 + xOffset1 * scale1;
+        } else {
+            x1 = e1.x2 - xOffset1 * scale1;
+        }
+        colorE1 = colorLerp(e1.color2, e1.color1, scale1);
+        scale1 += setp1;
+        //setPixel(x1, y, e1.color2);
+
+        Span span(x1, x2, y, colorE1, colorE2);
+        drawSpan(span);
+    }
+}
+
+void Raster::drawTriangle(int2 p0, int2 p1, int2 p2, Rgba c0, Rgba c1, Rgba c2) {
+
+    //优化1 不画3个点都不在坐标内的三角形
+    if (!isIn(p0) && !isIn(p1) && !isIn(p2)) {
+        return;
+    }
+
+    Ege eges[3] = {
+        Ege(p0.x, p0.y, p1.x, p1.y, c0, c1),
+        Ege(p1.x, p1.y, p2.x, p2.y, c1, c2),
+        Ege(p2.x, p2.y, p0.x, p0.y, c2, c0),
+    };
+
+    int iMax = 0;
+    int length = eges[0].y2 - eges[0].y1;
+
+    int curLength = 0;
+
+    for (int i = 1; i < 3; i++) {
+        curLength = eges[i].y2 - eges[i].y1;
+        if (curLength > length) {
+            iMax = i;
+        }
+    }
+
+    int iShort1 = (iMax + 1) % 3;
+    int iShort2 = (iMax + 2) % 3;
+
+    //printf("%d, %d, %d\n", iMax, iShort1, iShort2);
+
+    drawEge(eges[iMax], eges[iShort1]);
+    drawEge(eges[iMax], eges[iShort2]);
+}
+
 void Raster::drawArray(DRAWMODE mode, const float2* points, size_t count) {
     switch (mode) {
         case DM_POINTS:
@@ -242,4 +341,11 @@ bool Raster::setPixel(int x, int y, Rgba color) {
     }
     //行列是反的
     buffer[ (_height - y) * _width + x] = color;
+}
+
+bool Raster::isIn(int2 point) {
+    if (point.x >= 0 && point.x <= _width && point.y >= 0 && point.y < _height) {
+        return true;
+    }
+    return false;
 }

src/Raster.h

@@ -15,6 +15,7 @@
 #define RESTER_H
 
 #include "common.h"
+#include "Rgba.h"
 
 enum DRAWMODE {
     DM_POINTS = 0,
@@ -23,6 +24,62 @@ enum DRAWMODE {
     DM_LINES_TRIP = 3
 };
 
+class Span {
+public:
+    int xStart;
+    int xEnd;
+    int y;
+
+    Rgba color1;
+    Rgba color2;
+
+    Span(int xStart, int xEnd, int y, Rgba color1, Rgba color2) {
+
+        if (xStart < xEnd) {
+            this->xStart = xStart;
+            this->xEnd = xEnd;
+            this->color1 = color1;
+            this->color2 = color2;
+        } else {
+            this->xStart = xEnd;
+            this->xEnd = xStart;
+            this->color1 = color2;
+            this->color2 = color1;
+        }
+
+        this->y = y;
+    }
+};
+
+class Ege {
+public:
+    int x1;
+    int y1;
+    Rgba color1;
+
+    int x2;
+    int y2;
+    Rgba color2;
+
+    Ege(int x1, int y1, int x2, int y2, Rgba color1, Rgba color2) {
+        if (y1 < y2) {
+            this->x1 = x1;
+            this->y1 = y1;
+            this->x2 = x2;
+            this->y2 = y2;
+            this->color1 = color1;
+            this->color2 = color2;
+        } else {
+            this->x1 = x2;
+            this->y1 = y2;
+            this->x2 = x1;
+            this->y2 = y1;
+            this->color1 = color2;
+            this->color2 = color1;
+        }
+    }
+};
+
 class Raster {
 public:
     Rgba* buffer;
@@ -31,12 +88,16 @@ public:
     void drawPoint(int x, int y, Rgba color = Rgba(255, 0, 0, 0), int pointSize = 1);
     void drawLine(float2 p1, float2 p2, Rgba color = Rgba(255, 0, 0, 0));
     void drawLine(float2 p1, float2 p2, Rgba color1, Rgba color2);
+    void drawSpan(const Span &span);
+    void drawEge(const Ege& e1, const Ege& e2);
+    void drawTriangle(int2 p0, int2 p1, int2 p2, Rgba c0, Rgba c1, Rgba c2);
     void drawArray(DRAWMODE mode, const float2* points, size_t count);
     void drawFilledRect(int startX, int startY, int width, int height);
     void drawRect(const int2* points, const Rgba* colors);
     int size();
     void clean();
     bool setPixel(int x, int y, Rgba color);
+    bool isIn(int2 point);
 private:
     int _width;
     int _height;

src/Rgba.h

@@ -14,6 +14,8 @@
 #ifndef RGBA_H
 #define RGBA_H
 
+#include "stdio.h"
+
 class Rgba {
 public:
     Rgba(unsigned char r = 0, unsigned char g = 0, unsigned char b = 0, unsigned char a = 0);
@@ -40,5 +42,6 @@ inline Rgba colorLerp(const Rgba& color1, const Rgba& color2, float step) {
     return ret;
 }
 
+
 #endif /* RGBA_H */
 

src/draw_triangle.cc

@@ -0,0 +1,159 @@
+#include <iostream>
+#include <math.h>
+#include <cairo.h>
+#include <gtk/gtk.h>
+#include "Rgba.h"
+#include "Raster.h"
+#include "common.h"
+
+using namespace std;
+
+
+gint height = 500;
+gint width = 500;
+
+Raster raster(width, height);
+
+/**
+ * 使用drawSpan画线
+ */
+void example1() {
+    Span span(100, 400, 250, Rgba(255, 0, 0, 0), Rgba(255, 0, 0, 0));
+
+    raster.drawSpan(span);
+
+}
+
+/**
+ * 使用斜率画斜线
+ */
+void example2() {
+
+    static int x = 0;
+
+    if (x >= width) {
+        x = 0;
+    }
+
+    Ege e2(x++, 50, 250, 250, Rgba(255, 0, 0, 0), Rgba(255, 0, 0, 0));
+
+    //计算跨度
+    float xOffset = e2.x2 - e2.x1;
+    float yOffset = e2.y2 - e2.y1;
+
+    //计算斜率
+    float slope = xOffset / yOffset;
+
+    //以跨度大
+    for (float y = e2.y1; y < e2.y2; y++) {
+        float x;
+        // --> (x - e2.x1) / (y - e2.y1) = slope
+        // --> x - e2. x1 = slope * (y - e2.y1)
+        x = slope * (y - e2.y1) + e2.x1;
+        raster.setPixel(x, y, Rgba(255, 0, 0, 0));
+    }
+}
+
+void example3() {
+    //Ege e1(250, 250, 350, 50);
+    //Ege e2(250, 250, 100, 150);
+
+    Ege e1(250, 250, 350, 50, Rgba(255, 0, 0, 0), Rgba(255, 0, 0, 0));
+    Ege e2(100, 150, 350, 50, Rgba(255, 0, 0, 0), Rgba(255, 0, 0, 0));
+
+    raster.drawPoint(e1.x1, e1.y1, Rgba(255, 0, 0, 0), 3);
+    raster.drawPoint(e1.x2, e1.y2, Rgba(255, 0, 0, 0), 3);
+
+    raster.drawPoint(e2.x1, e2.y1, Rgba(255, 0, 0, 0), 3);
+    raster.drawPoint(e2.x2, e2.y2, Rgba(255, 0, 0, 0), 3);
+
+    raster.drawEge(e1, e2);
+}
+
+void example4() {
+
+    int2 p[3] = {
+        int2(50, 50),
+        int2(250, 250),
+        int2(300, 150)
+    };
+
+    //            int2 p[3] = {
+    //                int2(100, 150),
+    //                int2(250, 250),
+    //                int2(350, 50)
+    //            };
+
+    Ege e0(p[0].x, p[0].y, p[1].x, p[1].y, Rgba(255, 0, 0, 0), Rgba(0, 255, 0, 0));
+    Ege e1(p[1].x, p[1].y, p[2].x, p[2].y, Rgba(0, 255, 0, 0), Rgba(0, 0, 255, 0));
+    Ege e2(p[2].x, p[2].y, p[0].x, p[0].y, Rgba(0, 0, 255, 0), Rgba(255, 0, 0, 0));
+
+    raster.drawPoint(e0.x1, e0.y1, Rgba(255, 0, 0, 0), 3);
+    raster.drawPoint(e0.x2, e0.y2, Rgba(255, 0, 0, 0), 3);
+
+    raster.drawPoint(e2.x1, e2.y1, Rgba(255, 0, 0, 0), 3);
+    raster.drawPoint(e2.x2, e2.y2, Rgba(255, 0, 0, 0), 3);
+
+    //raster.drawEge(e0, e1);
+    //raster.drawEge(e0, e2);
+
+
+    //        raster.drawEge(e1, e0);
+    //        raster.drawEge(e1, e2);
+
+
+    raster.drawTriangle(p[0], p[1], p[2], Rgba(255, 0, 0, 0), Rgba(0, 255, 0, 0), Rgba(0, 0, 255, 0));
+}
+
+unsigned char* makeBitmap() {
+    raster.clean();
+
+    example4();
+
+    return (unsigned char*) raster.buffer;
+}
+
+void render(GtkWidget *widget) {
+    //允许窗口可以绘图
+    gtk_widget_set_app_paintable(widget, TRUE);
+    gtk_widget_realize(widget);
+    gtk_widget_queue_draw(widget);
+
+    //模拟一张图片
+    unsigned char* data = makeBitmap();
+
+    GdkPixbuf *pixbuf = gdk_pixbuf_new_from_data(data, GDK_COLORSPACE_RGB, TRUE, 8, width, height, width * 4, NULL, NULL);
+
+    GdkPixmap *pixmap = NULL;
+
+    gdk_pixbuf_render_pixmap_and_mask(pixbuf, &pixmap, NULL, 128);
+
+    gdk_window_set_back_pixmap(widget->window, pixmap, FALSE);
+
+    g_object_unref(pixbuf);
+    g_object_unref(pixmap);
+    //delete data;
+}
+
+int main(int argc, char* argv[]) {
+
+    gtk_init(&argc, &argv);
+
+    //创建窗口
+    GtkWidget *window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
+    gtk_widget_set_size_request(window, width, height);
+
+    gtk_window_set_title(GTK_WINDOW(window), "Gtk testing");
+    gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER_ALWAYS);
+
+    //窗口关闭时候，关闭程序
+    g_signal_connect(window, "destroy", G_CALLBACK(gtk_main_quit), NULL);
+    //设置渲染
+    g_signal_connect(window, "expose-event", G_CALLBACK(render), window);
+
+
+    gtk_widget_show_all(window);
+    gtk_main();
+
+    return 0;
+}