If both view and primitive scissors are set set their intersection as scissor region.

src/bgfx_p.h

@@ -182,6 +182,18 @@ namespace bgfx
 			return UINT64_C(0) == ui64;
 		}
 
+		void intersect(const Rect& _a, const Rect& _b)
+		{
+			const uint16_t sx = uint16_max(_a.m_x, _b.m_x);
+			const uint16_t sy = uint16_max(_a.m_y, _b.m_y);
+			const uint16_t ex = uint16_min(_a.m_x + _a.m_width,  _b.m_x + _b.m_width );
+			const uint16_t ey = uint16_min(_a.m_y + _a.m_height, _b.m_y + _b.m_height);
+			m_x = sx;
+			m_y = sy;
+			m_width  = ex - sx;
+			m_height = ey - sy;
+		}
+
 		uint16_t m_x;
 		uint16_t m_y;
 		uint16_t m_width;

src/renderer_d3d11.cpp

@@ -2325,6 +2325,8 @@ namespace bgfx
 		D3D11_PRIMITIVE_TOPOLOGY primType = D3D11_PRIMITIVE_TOPOLOGY_TRIANGLELIST;
 		deviceCtx->IASetPrimitiveTopology(primType);
 		uint32_t primNumVerts = 3;
+		bool viewHasScissor = false;
+		Rect viewScissorRect;
 
 		uint32_t statsNumPrimsSubmitted = 0;
 		uint32_t statsNumIndices = 0;
@@ -2367,7 +2369,10 @@ namespace bgfx
 						s_renderCtx.setRenderTarget(rt);
 					}
 
-					Rect& rect = m_render->m_rect[view];
+					const Rect& rect = m_render->m_rect[view];
+					const Rect& scissorRect = m_render->m_scissor[view];
+					viewHasScissor = !scissorRect.isZero();
+					viewScissorRect = viewHasScissor ? scissorRect : rect;
 
 					D3D11_VIEWPORT vp;
 					vp.TopLeftX = rect.m_x;
@@ -2403,21 +2408,21 @@ namespace bgfx
 
 					if (UINT16_MAX == scissor)
 					{
-						const Rect& scissorRect = m_render->m_scissor[view];
-						scissorEnabled = !scissorRect.isZero();
-						if (scissorEnabled)
+						scissorEnabled = viewHasScissor;
+						if (viewHasScissor)
 						{
 							D3D11_RECT rc;
-							rc.left = scissorRect.m_x;
-							rc.top = scissorRect.m_y;
-							rc.right = scissorRect.m_x + scissorRect.m_width;
-							rc.bottom = scissorRect.m_y + scissorRect.m_height;
+							rc.left = viewScissorRect.m_x;
+							rc.top = viewScissorRect.m_y;
+							rc.right = viewScissorRect.m_x + viewScissorRect.m_width;
+							rc.bottom = viewScissorRect.m_y + viewScissorRect.m_height;
 							deviceCtx->RSSetScissorRects(1, &rc);
 						}
 					}
 					else
 					{
-						const Rect& scissorRect = m_render->m_rectCache.m_cache[scissor];
+						Rect scissorRect;
+						scissorRect.intersect(viewScissorRect, m_render->m_rectCache.m_cache[scissor]);
 						scissorEnabled = true;
 						D3D11_RECT rc;
 						rc.left = scissorRect.m_x;

src/renderer_d3d9.cpp

@@ -2261,6 +2261,8 @@ namespace bgfx
 		uint32_t blendFactor = 0;
 		D3DPRIMITIVETYPE primType = D3DPT_TRIANGLELIST;
 		uint32_t primNumVerts = 3;
+		bool viewHasScissor = false;
+		Rect viewScissorRect;
 
 		uint32_t statsNumPrimsSubmitted = 0;
 		uint32_t statsNumIndices = 0;
@@ -2305,7 +2307,11 @@ namespace bgfx
 						s_renderCtx.setRenderTarget(rt);
 					}
 
-					Rect& rect = m_render->m_rect[view];
+					const Rect& rect = m_render->m_rect[view];
+					const Rect& scissorRect = m_render->m_scissor[view];
+					viewHasScissor = !scissorRect.isZero();
+					viewScissorRect = viewHasScissor ? scissorRect : rect;
+
 					D3DVIEWPORT9 vp;
 					vp.X = rect.m_x;
 					vp.Y = rect.m_y;
@@ -2370,23 +2376,22 @@ namespace bgfx
 
 					if (UINT16_MAX == scissor)
 					{
-						const Rect& scissorRect = m_render->m_scissor[view];
-						bool scissorEnabled = !scissorRect.isZero();
-						DX_CHECK(device->SetRenderState(D3DRS_SCISSORTESTENABLE, scissorEnabled) );
-						if (scissorEnabled)
+						DX_CHECK(device->SetRenderState(D3DRS_SCISSORTESTENABLE, viewHasScissor) );
+						if (viewHasScissor)
 						{
 							RECT rc;
-							rc.left = scissorRect.m_x;
-							rc.top = scissorRect.m_y;
-							rc.right = scissorRect.m_x + scissorRect.m_width;
-							rc.bottom = scissorRect.m_y + scissorRect.m_height;
+							rc.left = viewScissorRect.m_x;
+							rc.top = viewScissorRect.m_y;
+							rc.right = viewScissorRect.m_x + viewScissorRect.m_width;
+							rc.bottom = viewScissorRect.m_y + viewScissorRect.m_height;
 							DX_CHECK(device->SetScissorRect(&rc) );
 						}
 					}
 					else
 					{
+						Rect scissorRect;
+						scissorRect.intersect(viewScissorRect, m_render->m_rectCache.m_cache[scissor]);
 						DX_CHECK(device->SetRenderState(D3DRS_SCISSORTESTENABLE, true) );
-						const Rect& scissorRect = m_render->m_rectCache.m_cache[scissor];
 						RECT rc;
 						rc.left = scissorRect.m_x;
 						rc.top = scissorRect.m_y;

src/renderer_gl.cpp

@@ -2819,6 +2819,8 @@ namespace bgfx
 		uint32_t primNumVerts = 3;
 		uint32_t baseVertex = 0;
 		GLuint currentVao = 0;
+		bool viewHasScissor = false;
+		Rect viewScissorRect;
 
 		uint32_t statsNumPrimsSubmitted = 0;
 		uint32_t statsNumIndices = 0;
@@ -2862,7 +2864,10 @@ namespace bgfx
 						height = s_renderCtx.setRenderTarget(rt, m_render->m_resolution.m_height);
 					}
 
-					Rect& rect = m_render->m_rect[view];
+					const Rect& rect = m_render->m_rect[view];
+					const Rect& scissorRect = m_render->m_scissor[view];
+					viewHasScissor = !scissorRect.isZero();
+					viewScissorRect = viewHasScissor ? scissorRect : rect;
 
 					GL_CHECK(glViewport(rect.m_x, height-rect.m_height-rect.m_y, rect.m_width, rect.m_height) );
 
@@ -2887,12 +2892,10 @@ namespace bgfx
 
 					if (UINT16_MAX == scissor)
 					{
-						const Rect& scissorRect = m_render->m_scissor[view];
-						bool scissor = !scissorRect.isZero();
-						if (scissor)
+						if (viewHasScissor)
 						{
 							GL_CHECK(glEnable(GL_SCISSOR_TEST) );
-							GL_CHECK(glScissor(scissorRect.m_x, height-scissorRect.m_height-scissorRect.m_y, scissorRect.m_width, scissorRect.m_height) );
+							GL_CHECK(glScissor(viewScissorRect.m_x, height-viewScissorRect.m_height-viewScissorRect.m_y, viewScissorRect.m_width, viewScissorRect.m_height) );
 						}
 						else
 						{
@@ -2901,7 +2904,8 @@ namespace bgfx
 					}
 					else
 					{
-						const Rect& scissorRect = m_render->m_rectCache.m_cache[scissor];
+						Rect scissorRect;
+						scissorRect.intersect(viewScissorRect, m_render->m_rectCache.m_cache[scissor]);
 						GL_CHECK(glEnable(GL_SCISSOR_TEST) );
 						GL_CHECK(glScissor(scissorRect.m_x, height-scissorRect.m_height-scissorRect.m_y, scissorRect.m_width, scissorRect.m_height) );
 					}