Fixed incomplete framebuffer.

src/glimports.h

@@ -80,6 +80,7 @@ typedef void           (GL_APIENTRYP PFNGLDISABLEPROC) (GLenum cap);
 typedef void           (GL_APIENTRYP PFNGLDISABLEVERTEXATTRIBARRAYPROC) (GLuint index);
 typedef void           (GL_APIENTRYP PFNGLDRAWARRAYSPROC) (GLenum mode, GLint first, GLsizei count);
 typedef void           (GL_APIENTRYP PFNGLDRAWARRAYSINSTANCEDPROC) (GLenum mode, GLint first, GLsizei count, GLsizei instancecount);
+typedef void           (GL_APIENTRYP PFNGLDRAWBUFFERPROC) (GLenum mode);
 typedef void           (GL_APIENTRYP PFNGLDRAWELEMENTSPROC) (GLenum mode, GLsizei count, GLenum type, const void *indices);
 typedef void           (GL_APIENTRYP PFNGLDRAWELEMENTSINSTANCEDPROC) (GLenum mode, GLsizei count, GLenum type, const void *indices, GLsizei instancecount);
 typedef void           (GL_APIENTRYP PFNGLENABLEPROC) (GLenum cap);
@@ -118,6 +119,7 @@ typedef void           (GL_APIENTRYP PFNGLPOINTSIZEPROC) (GLfloat size);
 typedef void           (GL_APIENTRYP PFNGLPROGRAMBINARYPROC) (GLuint program, GLenum binaryFormat, const void *binary, GLsizei length);
 typedef void           (GL_APIENTRYP PFNGLPROGRAMPARAMETERIPROC) (GLuint program, GLenum pname, GLint value);
 typedef void           (GL_APIENTRYP PFNGLQUERYCOUNTERPROC) (GLuint id, GLenum target);
+typedef void           (GL_APIENTRYP PFNGLREADBUFFERPROC) (GLenum mode);
 typedef void           (GL_APIENTRYP PFNGLREADPIXELSPROC) (GLint x, GLint y, GLsizei width, GLsizei height, GLenum format, GLenum type, void *pixels);
 typedef void           (GL_APIENTRYP PFNGLRENDERBUFFERSTORAGEPROC) (GLenum target, GLenum internalformat, GLsizei width, GLsizei height);
 typedef void           (GL_APIENTRYP PFNGLRENDERBUFFERSTORAGEMULTISAMPLEPROC) (GLenum target, GLsizei samples, GLenum internalformat, GLsizei width, GLsizei height);
@@ -211,6 +213,7 @@ GL_IMPORT______(false, PFNGLDISABLEPROC,                           glDisable);
 GL_IMPORT______(false, PFNGLDISABLEVERTEXATTRIBARRAYPROC,          glDisableVertexAttribArray);
 GL_IMPORT______(false, PFNGLDRAWARRAYSPROC,                        glDrawArrays);
 GL_IMPORT______(true,  PFNGLDRAWARRAYSINSTANCEDPROC,               glDrawArraysInstanced);
+GL_IMPORT______(true,  PFNGLDRAWBUFFERPROC,                        glDrawBuffer);
 GL_IMPORT______(false, PFNGLDRAWELEMENTSPROC,                      glDrawElements);
 GL_IMPORT______(true,  PFNGLDRAWELEMENTSINSTANCEDPROC,             glDrawElementsInstanced);
 GL_IMPORT______(false, PFNGLENABLEPROC,                            glEnable);
@@ -248,6 +251,7 @@ GL_IMPORT______(false, PFNGLPIXELSTOREIPROC,                       glPixelStorei
 GL_IMPORT______(true,  PFNGLPROGRAMBINARYPROC,                     glProgramBinary);
 GL_IMPORT______(true,  PFNGLPROGRAMPARAMETERIPROC,                 glProgramParameteri);
 GL_IMPORT______(true,  PFNGLQUERYCOUNTERPROC,                      glQueryCounter);
+GL_IMPORT______(true,  PFNGLREADBUFFERPROC,                        glReadBuffer);
 GL_IMPORT______(false, PFNGLREADPIXELSPROC,                        glReadPixels);
 GL_IMPORT______(true,  PFNGLRENDERBUFFERSTORAGEPROC,               glRenderbufferStorage);
 GL_IMPORT______(true,  PFNGLRENDERBUFFERSTORAGEMULTISAMPLEPROC,    glRenderbufferStorageMultisample);

src/renderer_gl.cpp

@@ -2150,7 +2150,8 @@ namespace bgfx
 
 		bool needResolve = false;
 
-		for (uint32_t ii = 0, colorIdx = 0; ii < _num; ++ii)
+		uint32_t colorIdx = 0;
+		for (uint32_t ii = 0; ii < _num; ++ii)
 		{
 			TextureHandle handle = _handles[ii];
 			if (isValid(handle) )
@@ -2195,6 +2196,19 @@ namespace bgfx
 			}
 		}
 
+		if (BX_ENABLED(!BGFX_CONFIG_RENDERER_OPENGL) )
+		{
+			if (0 == colorIdx)
+			{
+				// When only depth is attached disable draw buffer to avoid
+				// GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER.
+				glDrawBuffer(GL_NONE);
+			}
+
+			// Disable read buffer to avoid GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER.
+			glReadBuffer(GL_NONE);
+		}
+
 		BX_CHECK(GL_FRAMEBUFFER_COMPLETE ==  glCheckFramebufferStatus(GL_FRAMEBUFFER)
 			, "glCheckFramebufferStatus failed 0x%08x"
 			, glCheckFramebufferStatus(GL_FRAMEBUFFER)