rhi: Take mip size into account for render target size

Also extend autotesting, both for rendering into a given mip level
and for rendering into a given cubemap face.

Change-Id: Ida94b71150477ceb50a3b5616d8b7be13174558b
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

7 files changed, 27 insertions, 8 deletions

diff --git a/src/gui/rhi/qrhi.cpp b/src/gui/rhi/qrhi.cpp
index 7d2af37e96..1eb26985bf 100644
--- a/src/gui/rhi/qrhi.cpp
+++ b/src/gui/rhi/qrhi.cpp
@@ -582,6 +582,13 @@ Q_LOGGING_CATEGORY(QRHI_LOG_INFO, "qt.rhi.general")
     practice this will be reported as unsupported with OpenGL ES 2.0 and OpenGL
     2.x contexts, because GLSL 100 es and versions before 130 do not support
     this function.
+
+    \value RenderToNonBaseMipLevel Indicates that specifying a mip level other
+    than 0 is supported when creating a QRhiTextureRenderTarget with a
+    QRhiTexture as its color attachment. When not supported, build() will fail
+    whenever the target mip level is not zero. In practice this feature will be
+    unsupported with OpenGL ES 2.0, while it will likely be supported everywhere
+    else.
  */
 
 /*!
diff --git a/src/gui/rhi/qrhi_p.h b/src/gui/rhi/qrhi_p.h
index 5c4cf4a144..5ef415e96c 100644
--- a/src/gui/rhi/qrhi_p.h
+++ b/src/gui/rhi/qrhi_p.h
@@ -1446,7 +1446,8 @@ public:
         TriangleFanTopology,
         ReadBackNonUniformBuffer,
         ReadBackNonBaseMipLevel,
-        TexelFetch
+        TexelFetch,
+        RenderToNonBaseMipLevel
     };
 
     enum BeginFrameFlag {
diff --git a/src/gui/rhi/qrhid3d11.cpp b/src/gui/rhi/qrhid3d11.cpp
index 0665304a19..c3c40b4cc4 100644
--- a/src/gui/rhi/qrhid3d11.cpp
+++ b/src/gui/rhi/qrhid3d11.cpp
@@ -470,6 +470,8 @@ bool QRhiD3D11::isFeatureSupported(QRhi::Feature feature) const
         return true;
     case QRhi::TexelFetch:
         return true;
+    case QRhi::RenderToNonBaseMipLevel:
+        return true;
     default:
         Q_UNREACHABLE();
         return false;
@@ -3243,7 +3245,7 @@ bool QD3D11TextureRenderTarget::build()
             }
             ownsRtv[attIndex] = true;
             if (attIndex == 0) {
-                d.pixelSize = texD->pixelSize();
+                d.pixelSize = rhiD->q->sizeForMipLevel(colorAtt.level(), texD->pixelSize());
                 d.sampleCount = int(texD->sampleDesc.Count);
             }
         } else if (rb) {
diff --git a/src/gui/rhi/qrhigles2.cpp b/src/gui/rhi/qrhigles2.cpp
index 227dace90f..1e97d2ed0c 100644
--- a/src/gui/rhi/qrhigles2.cpp
+++ b/src/gui/rhi/qrhigles2.cpp
@@ -769,6 +769,8 @@ bool QRhiGles2::isFeatureSupported(QRhi::Feature feature) const
         return caps.nonBaseLevelFramebufferTexture;
     case QRhi::TexelFetch:
         return caps.texelFetch;
+    case QRhi::RenderToNonBaseMipLevel:
+        return caps.nonBaseLevelFramebufferTexture;
     default:
         Q_UNREACHABLE();
         return false;
@@ -3930,7 +3932,7 @@ bool QGles2TextureRenderTarget::build()
             rhiD->f->glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + uint(attIndex), faceTargetBase + uint(colorAtt.layer()),
                                             texD->texture, colorAtt.level());
             if (attIndex == 0) {
-                d.pixelSize = texD->pixelSize();
+                d.pixelSize = rhiD->q->sizeForMipLevel(colorAtt.level(), texD->pixelSize());
                 d.sampleCount = 1;
             }
         } else if (renderBuffer) {
diff --git a/src/gui/rhi/qrhimetal.mm b/src/gui/rhi/qrhimetal.mm
index 0806c8a052..f021e78097 100644
--- a/src/gui/rhi/qrhimetal.mm
+++ b/src/gui/rhi/qrhimetal.mm
@@ -564,6 +564,8 @@ bool QRhiMetal::isFeatureSupported(QRhi::Feature feature) const
         return true;
     case QRhi::TexelFetch:
         return true;
+    case QRhi::RenderToNonBaseMipLevel:
+        return true;
     default:
         Q_UNREACHABLE();
         return false;
@@ -2863,6 +2865,7 @@ QRhiRenderPassDescriptor *QMetalTextureRenderTarget::newCompatibleRenderPassDesc
 
 bool QMetalTextureRenderTarget::build()
 {
+    QRHI_RES_RHI(QRhiMetal);
     const bool hasColorAttachments = m_desc.cbeginColorAttachments() != m_desc.cendColorAttachments();
     Q_ASSERT(hasColorAttachments || m_desc.depthTexture());
     Q_ASSERT(!m_desc.depthStencilBuffer() || !m_desc.depthTexture());
@@ -2879,7 +2882,7 @@ bool QMetalTextureRenderTarget::build()
         if (texD) {
             dst = texD->d->tex;
             if (attIndex == 0) {
-                d->pixelSize = texD->pixelSize();
+                d->pixelSize = rhiD->q->sizeForMipLevel(it->level(), texD->pixelSize());
                 d->sampleCount = texD->samples;
             }
         } else if (rbD) {
diff --git a/src/gui/rhi/qrhinull.cpp b/src/gui/rhi/qrhinull.cpp
index 8c07e09b32..7b18c9156b 100644
--- a/src/gui/rhi/qrhinull.cpp
+++ b/src/gui/rhi/qrhinull.cpp
@@ -740,11 +740,13 @@ QRhiRenderPassDescriptor *QNullTextureRenderTarget::newCompatibleRenderPassDescr
 
 bool QNullTextureRenderTarget::build()
 {
+    QRHI_RES_RHI(QRhiNull);
     d.rp = QRHI_RES(QNullRenderPassDescriptor, m_renderPassDesc);
     if (m_desc.cbeginColorAttachments() != m_desc.cendColorAttachments()) {
-        QRhiTexture *tex = m_desc.cbeginColorAttachments()->texture();
-        QRhiRenderBuffer *rb = m_desc.cbeginColorAttachments()->renderBuffer();
-        d.pixelSize = tex ? tex->pixelSize() : rb->pixelSize();
+        const QRhiColorAttachment *colorAtt = m_desc.cbeginColorAttachments();
+        QRhiTexture *tex = colorAtt->texture();
+        QRhiRenderBuffer *rb = colorAtt->renderBuffer();
+        d.pixelSize = tex ? rhiD->q->sizeForMipLevel(colorAtt->level(), tex->pixelSize()) : rb->pixelSize();
     } else if (m_desc.depthStencilBuffer()) {
         d.pixelSize = m_desc.depthStencilBuffer()->pixelSize();
     } else if (m_desc.depthTexture()) {
diff --git a/src/gui/rhi/qrhivulkan.cpp b/src/gui/rhi/qrhivulkan.cpp
index 211ee195e5..49e634e248 100644
--- a/src/gui/rhi/qrhivulkan.cpp
+++ b/src/gui/rhi/qrhivulkan.cpp
@@ -4023,6 +4023,8 @@ bool QRhiVulkan::isFeatureSupported(QRhi::Feature feature) const
         return true;
     case QRhi::TexelFetch:
         return true;
+    case QRhi::RenderToNonBaseMipLevel:
+        return true;
     default:
         Q_UNREACHABLE();
         return false;
@@ -5911,7 +5913,7 @@ bool QVkTextureRenderTarget::build()
             }
             views.append(rtv[attIndex]);
             if (attIndex == 0) {
-                d.pixelSize = texD->pixelSize();
+                d.pixelSize = rhiD->q->sizeForMipLevel(it->level(), texD->pixelSize());
                 d.sampleCount = texD->samples;
             }
         } else if (rbD) {