add initial examples, replacing the 'Demos/Demos3'. Will make it work cross-platform, OpenGL3/OpenGL2 and add more examples to it.

examples/OpenGLWindow/GLRenderToTexture.cpp

@@ -0,0 +1,135 @@
+
+///See http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-14-render-to-texture/
+
+
+#include "GLRenderToTexture.h"
+#include "Bullet3Common/b3Scalar.h" // for b3Assert
+#include <string.h>
+#include <stdio.h>
+
+bool gIntelLinuxglDrawBufferWorkaround=false;
+
+GLRenderToTexture::GLRenderToTexture()
+:m_framebufferName(0)
+{
+#if !defined(_WIN32) && !defined(__APPLE__)
+ const GLubyte* ven = glGetString(GL_VENDOR);
+	printf("ven = %s\n",ven);
+
+ if (strncmp((const char*)ven,"Intel",5)==0)
+       {
+               printf("Workaround for some crash in the Intel OpenGL driver on Linux/Ubuntu\n");
+               gIntelLinuxglDrawBufferWorkaround=true;
+       }
+#endif//!defined(_WIN32) && !defined(__APPLE__)
+
+}
+
+void GLRenderToTexture::init(int width, int height, GLuint textureId, int renderTextureType)
+{
+	m_renderTextureType = renderTextureType;
+
+	glGenFramebuffers(1, &m_framebufferName);
+	glBindFramebuffer(GL_FRAMEBUFFER, m_framebufferName);
+
+
+
+	// The depth buffer
+//	glGenRenderbuffers(1, &m_depthrenderbuffer);
+
+//	glBindRenderbuffer(GL_RENDERBUFFER, m_depthrenderbuffer);
+//	glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT, width, height);
+//	glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, m_depthrenderbuffer);
+
+		switch (m_renderTextureType)
+	{
+	case RENDERTEXTURE_COLOR:
+		{
+			glFramebufferTexture(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, textureId, 0);
+			break;
+		}
+		case RENDERTEXTURE_DEPTH:
+		{
+			glFramebufferTexture(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, textureId, 0);
+			break;
+		}
+		default:
+			{
+			b3Assert(0);
+			}
+	};
+
+
+	glBindFramebuffer( GL_FRAMEBUFFER, 0 );
+
+
+}
+
+bool GLRenderToTexture::enable()
+{
+	bool status = false;
+
+	glBindFramebuffer(GL_FRAMEBUFFER, m_framebufferName);
+
+
+	switch (m_renderTextureType)
+	{
+	case RENDERTEXTURE_COLOR:
+		{
+			// Set the list of draw buffers.
+			GLenum drawBuffers[2] = {GL_COLOR_ATTACHMENT0,0};
+			glDrawBuffers(1, drawBuffers);
+			break;
+		}
+		case RENDERTEXTURE_DEPTH:
+		{
+			//Intel OpenGL driver crashes when using GL_NONE for glDrawBuffer on Linux, so use a workaround
+			if (gIntelLinuxglDrawBufferWorkaround)
+			{
+				GLenum drawBuffers[2] = { GL_COLOR_ATTACHMENT0,0};
+                glDrawBuffers(1, drawBuffers);
+			} else
+			{
+				glDrawBuffer(GL_NONE);
+			}
+			break;
+		}
+		default:
+			{
+			b3Assert(0);
+			}
+	};
+
+
+	// Always check that our framebuffer is ok
+	if(glCheckFramebufferStatus(GL_FRAMEBUFFER) == GL_FRAMEBUFFER_COMPLETE)
+	{
+		status = true;
+	}
+
+
+	return status;
+
+}
+
+void GLRenderToTexture::disable()
+{
+	glBindFramebuffer( GL_FRAMEBUFFER, 0 );
+}
+
+GLRenderToTexture::~GLRenderToTexture()
+{
+	glBindFramebuffer( GL_FRAMEBUFFER, 0 );
+
+	if (m_depthrenderbuffer)
+	{
+		glDeleteRenderbuffers(1,&m_depthrenderbuffer);
+	}
+
+
+	if( m_framebufferName)
+	{
+		glDeleteFramebuffers(1, &m_framebufferName);
+	}
+}
+