1 files changed, 102 insertions, 0 deletions
diff --git a/src/libjin/Graphics/je_canvas.cpp b/src/libjin/Graphics/je_canvas.cpp
new file mode 100644
index 0000000..af9868b
--- /dev/null
+++ b/src/libjin/Graphics/je_canvas.cpp
@@ -0,0 +1,102 @@
+#include "../core/je_configuration.h"
+#if LIBJIN_MODULES_RENDER
+
+#include "../utils/je_macros.h"
+#include "je_canvas.h" 
+#include "je_window.h"
+
+namespace jin
+{
+	namespace graphics
+	{
+
+		/*class member*/ const Canvas* Canvas::current = nullptr;
+		/*class member*/ const Canvas* const Canvas::DEFAULT_CANVAS = new Canvas(0);
+
+		/*class member*/ Canvas* Canvas::createCanvas(int w, int h)
+		{
+			return new Canvas(w, h);
+		}
+
+		Canvas::Canvas(GLuint n) 
+			: fbo(n)
+		{
+		}
+
+		Canvas::Canvas(int w, int h) 
+			: Drawable(w, h)
+		{
+			GLint current_fbo;
+			glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, &current_fbo);
+
+			// generate a new render buffer object 
+			fbo = gl.genFrameBuffer();
+			gl.bindFrameBuffer(fbo);
+
+			// generate texture save target
+			texture = gl.genTexture();
+			gl.bindTexture(texture);
+			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+			glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+			gl.texImage(GL_RGBA8, w, h, GL_RGBA, GL_UNSIGNED_BYTE, NULL);
+			gl.bindTexture(0);
+			glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, texture, 0);
+
+			GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
+
+			/* unbind framebuffer */
+			gl.bindFrameBuffer(current_fbo);
+		}
+
+		Canvas::~Canvas()
+		{
+		}
+
+		/*class member*/ bool Canvas::isBinded(const Canvas* cvs)
+		{
+			return current == cvs;
+		}
+
+		/**
+		* bind to canvas 
+		*/
+		/*class member*/ void Canvas::bind(Canvas* canvas)
+		{
+			if (isBinded(canvas)) return;
+			current = canvas;
+			gl.bindFrameBuffer(canvas->fbo);
+			int w = canvas->size.w; 
+			int h = canvas->size.h;
+			/* set view port to canvas */
+			glViewport(0, 0, w, h);
+			gl.ProjectionMatrix.setOrtho(0, w, 0, h, -1, 1);
+		}
+
+		/**
+		* bind to default screen render buffer. 
+		* do some coordinates transform work
+		* https://blog.csdn.net/liji_digital/article/details/79370841
+		* https://blog.csdn.net/lyx2007825/article/details/8792475
+		*/
+		/*class member*/ void Canvas::unbind()
+		{
+			if (isBinded(DEFAULT_CANVAS)) return;
+			current = DEFAULT_CANVAS;
+			/* get window size as viewport */
+			Window* wnd = Window::get();
+			int w = wnd->getW();
+			int h = wnd->getH();
+
+			glBindFramebuffer(GL_FRAMEBUFFER, DEFAULT_CANVAS->fbo);
+
+			/* set viewport on screen */
+			glViewport(0, 0, w, h);
+
+			gl.ProjectionMatrix.setOrtho(0, w, h, 0, -1, 1);
+
+		}
+
+	} // namespace graphics
+} // namespace jin
+
+#endif // LIBJIN_MODULES_RENDER
+\ No newline at end of file