Implement all texture formats for gl

...and add a semi-format that can be used to port code with the
'if modernGL then GL_R8 else GL_ALPHA' pattern (in order to support GLES
2.0).

src/rhi/qrhi.cpp

@@ -404,6 +404,12 @@ QT_BEGIN_NAMESPACE
 
     \value NPOTTextureRepeat Indicates that the \l{QRhiSampler::Repeat}{Repeat}
     mode is supported for textures with a non-power-of-two size.
+
+    \value RedOrAlpha8IsRed Indicates that the
+    \l{QRhiTexture::RED_OR_ALPHA8}{RED_OR_ALPHA8} format maps to a one
+    component 8-bit \c red format. This is the case for all backends except
+    OpenGL, where \c{GL_ALPHA}, a one component 8-bit \c alpha format, is used
+    instead. This is relevant for shader code that samples from the texture.
  */
 
 /*!
@@ -1862,12 +1868,22 @@ QRhiRenderBuffer::QRhiRenderBuffer(QRhiImplementation *rhi, Type type_, const QS
     note that flags() can modify the format when QRhiTexture::sRGB is set.
 
     \value UnknownFormat Not a valid format. This cannot be passed to setFormat().
-    \value RGBA8
-    \value BGRA8
-    \value R8
-    \value R16
-    \value D16
-    \value D32
+
+    \value RGBA8 Four component, unsigned normalized 8 bit per component. Always supported.
+
+    \value BGRA8 Four component, unsigned normalized 8 bit per component.
+
+    \value R8 One component, unsigned normalized 8 bit.
+
+    \value R16 One component, unsigned normalized 16 bit.
+
+    \value RED_OR_ALPHA8 Either same as R8, or is a similar format with the component swizzled to alpha,
+    depending on \l{QRhi::RedOrAlpha8IsRed}{RedOrAlpha8IsRed}.
+
+    \value D16 16-bit depth (normalized unsigned integer)
+
+    \value D32 32-bit depth (32-bit float)
+
     \value BC1
     \value BC2
     \value BC3
@@ -1875,9 +1891,11 @@ QRhiRenderBuffer::QRhiRenderBuffer(QRhiImplementation *rhi, Type type_, const QS
     \value BC5
     \value BC6H
     \value BC7
+
     \value ETC2_RGB8
     \value ETC2_RGB8A1
     \value ETC2_RGBA8
+
     \value ASTC_4x4
     \value ASTC_5x4
     \value ASTC_5x5

src/rhi/qrhi.h

@@ -643,6 +643,7 @@ public:
         BGRA8,
         R8,
         R16,
+        RED_OR_ALPHA8,
 
         D16,
         D32,
@@ -1251,7 +1252,8 @@ public:
         TessellationShaders,
         NonDynamicUniformBuffers,
         NonFourAlignedEffectiveIndexBufferOffset,
-        NPOTTextureRepeat
+        NPOTTextureRepeat,
+        RedOrAlpha8IsRed
     };
 
     enum BeginFrameFlag {

src/rhi/qrhi_p.h

@@ -181,7 +181,7 @@ public:
     {
         if (res->m_orphanedWithRsh) {
             qWarning("Attempted to perform something on an orphaned QRhiResource %p (%s). This is invalid.",
-                     res, res->m_objectName.constData());
+                     (void *) res, res->m_objectName.constData());
             return false;
         }
         return true;

src/rhi/qrhid3d11.cpp

@@ -401,6 +401,8 @@ bool QRhiD3D11::isFeatureSupported(QRhi::Feature feature) const
         return true;
     case QRhi::NPOTTextureRepeat:
         return true;
+    case QRhi::RedOrAlpha8IsRed:
+        return true;
     default:
         Q_UNREACHABLE();
         return false;
@@ -914,6 +916,8 @@ static inline DXGI_FORMAT toD3DTextureFormat(QRhiTexture::Format format, QRhiTex
         return DXGI_FORMAT_R8_UNORM;
     case QRhiTexture::R16:
         return DXGI_FORMAT_R16_UNORM;
+    case QRhiTexture::RED_OR_ALPHA8:
+        return DXGI_FORMAT_R8_UNORM;
 
     case QRhiTexture::D16:
         return DXGI_FORMAT_R16_TYPELESS;

src/rhi/qrhigles2.cpp

@@ -157,6 +157,22 @@ QT_BEGIN_NAMESPACE
     \brief Holds the OpenGL texture object that is backing a QRhiTexture instance.
  */
 
+#ifndef GL_BGRA
+#define GL_BGRA                           0x80E1
+#endif
+
+#ifndef GL_R8
+#define GL_R8                             0x8229
+#endif
+
+#ifndef GL_R16
+#define GL_R16                            0x822A
+#endif
+
+#ifndef GL_RED
+#define GL_RED                            0x1903
+#endif
+
 #ifndef GL_PRIMITIVE_RESTART_FIXED_INDEX
 #define GL_PRIMITIVE_RESTART_FIXED_INDEX  0x8D69
 #endif
@@ -290,6 +306,8 @@ bool QRhiGles2::create(QRhi::Flags flags)
     if (n > 0)
         f->glGetIntegerv(GL_COMPRESSED_TEXTURE_FORMATS, supportedCompressedFormats.data());
 
+    f->glGetIntegerv(GL_MAX_TEXTURE_SIZE, &caps.maxTextureSize);
+
     caps.msaaRenderBuffer = f->hasOpenGLExtension(QOpenGLExtensions::FramebufferMultisample)
             && f->hasOpenGLExtension(QOpenGLExtensions::FramebufferBlit);
 
@@ -297,7 +315,7 @@ bool QRhiGles2::create(QRhi::Flags flags)
     caps.npotTextureRepeat = f->hasOpenGLFeature(QOpenGLFunctions::NPOTTextureRepeat);
 
     const QSurfaceFormat actualFormat = ctx->format();
-    if (ctx->isOpenGLES())
+    if (actualFormat.renderableType() == QSurfaceFormat::OpenGLES)
         caps.fixedIndexPrimitiveRestart = actualFormat.version() >= qMakePair(3, 0);
     else
         caps.fixedIndexPrimitiveRestart = actualFormat.version() >= qMakePair(4, 3);
@@ -305,7 +323,11 @@ bool QRhiGles2::create(QRhi::Flags flags)
     if (caps.fixedIndexPrimitiveRestart)
         f->glEnable(GL_PRIMITIVE_RESTART_FIXED_INDEX);
 
-    f->glGetIntegerv(GL_MAX_TEXTURE_SIZE, &caps.maxTextureSize);
+    caps.bgraExternalFormat = f->hasOpenGLExtension(QOpenGLExtensions::BGRATextureFormat);
+    caps.bgraInternalFormat = caps.bgraExternalFormat && actualFormat.renderableType() == QSurfaceFormat::OpenGLES;
+
+    caps.sized8Formats = f->hasOpenGLExtension(QOpenGLExtensions::Sized8Formats);
+    caps.sized16Formats = f->hasOpenGLExtension(QOpenGLExtensions::Sized16Formats);
 
     nativeHandlesStruct.context = ctx;
 
@@ -512,11 +534,13 @@ bool QRhiGles2::isTextureFormatSupported(QRhiTexture::Format format, QRhiTexture
         return false;
 
     case QRhiTexture::BGRA8:
-        Q_FALLTHROUGH();
+        return caps.bgraExternalFormat;
+
     case QRhiTexture::R8:
-        Q_FALLTHROUGH();
+        return caps.sized8Formats;
+
     case QRhiTexture::R16:
-        return false; // ###
+        return caps.sized16Formats;
 
     default:
         break;
@@ -552,6 +576,8 @@ bool QRhiGles2::isFeatureSupported(QRhi::Feature feature) const
         return true;
     case QRhi::NPOTTextureRepeat:
         return caps.npotTextureRepeat;
+    case QRhi::RedOrAlpha8IsRed:
+        return false;
     default:
         Q_UNREACHABLE();
         return false;
@@ -1504,7 +1530,6 @@ void QRhiGles2::executeCommandBuffer(QRhiCommandBuffer *cb)
             break;
         case QGles2CommandBuffer::Command::ReadPixels:
         {
-            // ### more formats
             QRhiReadbackResult *result = cmd.args.readPixels.result;
             GLuint tex = cmd.args.readPixels.texture;
             GLuint fbo = 0;
@@ -2113,11 +2138,38 @@ bool QGles2Texture::prepareBuild(QSize *adjustedSize)
 
     target = isCube ? GL_TEXTURE_CUBE_MAP : GL_TEXTURE_2D;
 
-    // ### more formats
-    glintformat = GL_RGBA;
-    glformat = GL_RGBA;
-
     gltype = GL_UNSIGNED_BYTE;
+
+    switch (m_format) {
+    case QRhiTexture::RGBA8:
+        glintformat = GL_RGBA;
+        glformat = GL_RGBA;
+        break;
+    case QRhiTexture::BGRA8:
+        glintformat = rhiD->caps.bgraInternalFormat ? GL_BGRA : GL_RGBA;
+        glformat = GL_BGRA;
+        break;
+    case QRhiTexture::R16:
+        glintformat = GL_R16;
+        glformat = GL_RED;
+        gltype = GL_UNSIGNED_SHORT;
+        break;
+    case QRhiTexture::R8:
+        glintformat = GL_R8;
+        glformat = GL_RED;
+        break;
+    case QRhiTexture::RED_OR_ALPHA8:
+        // always alpha because we do not support core profile
+        glintformat = GL_ALPHA;
+        glformat = GL_ALPHA;
+        break;
+    default:
+        Q_UNREACHABLE();
+        glintformat = GL_RGBA;
+        glformat = GL_RGBA;
+        break;
+    }
+
     mipLevelCount = hasMipMaps ? rhiD->q->mipLevelsForSize(size) : 1;
 
     if (isCompressed) {

src/rhi/qrhigles2_p.h

@@ -558,14 +558,29 @@ public:
     QSurface *fallbackSurface = nullptr;
     mutable bool needsMakeCurrent = false;
     QOpenGLExtensions *f = nullptr;
-    struct {
+    struct Caps {
+        Caps()
+            : maxTextureSize(2048),
+              msaaRenderBuffer(false),
+              npotTexture(true),
+              npotTextureRepeat(true),
+              fixedIndexPrimitiveRestart(false),
+              bgraExternalFormat(false),
+              bgraInternalFormat(false),
+              sized8Formats(false),
+              sized16Formats(false)
+        { }
+        int maxTextureSize;
         // Multisample fb and blit are supported (GLES 3.0 or OpenGL 3.x). Not
         // the same as multisample textures!
-        bool msaaRenderBuffer = false;
-        bool npotTexture = true;
-        bool npotTextureRepeat = true;
-        bool fixedIndexPrimitiveRestart = false;
-        int maxTextureSize = 2048;
+        uint msaaRenderBuffer : 1;
+        uint npotTexture : 1;
+        uint npotTextureRepeat : 1;
+        uint fixedIndexPrimitiveRestart : 1;
+        uint bgraExternalFormat : 1;
+        uint bgraInternalFormat : 1;
+        uint sized8Formats : 1;
+        uint sized16Formats : 1;
     } caps;
     bool inFrame = false;
     bool inPass = false;

src/rhi/qrhimetal.mm

@@ -517,6 +517,8 @@ bool QRhiMetal::isFeatureSupported(QRhi::Feature feature) const
         return false;
     case QRhi::NPOTTextureRepeat:
         return true;
+    case QRhi::RedOrAlpha8IsRed:
+        return true;
     default:
         Q_UNREACHABLE();
         return false;
@@ -1952,6 +1954,8 @@ static inline MTLPixelFormat toMetalTextureFormat(QRhiTexture::Format format, QR
 #endif
     case QRhiTexture::R16:
         return MTLPixelFormatR16Unorm;
+    case QRhiTexture::RED_OR_ALPHA8:
+        return MTLPixelFormatR8Unorm;
 
     case QRhiTexture::D16:
         return MTLPixelFormatDepth16Unorm;

src/rhi/qrhivulkan.cpp

@@ -704,6 +704,8 @@ static inline VkFormat toVkTextureFormat(QRhiTexture::Format format, QRhiTexture
         return srgb ? VK_FORMAT_R8_SRGB : VK_FORMAT_R8_UNORM;
     case QRhiTexture::R16:
         return VK_FORMAT_R16_UNORM;
+    case QRhiTexture::RED_OR_ALPHA8:
+        return VK_FORMAT_R8_UNORM;
 
     case QRhiTexture::D16:
         return VK_FORMAT_D16_UNORM;
@@ -3044,6 +3046,8 @@ bool QRhiVulkan::isFeatureSupported(QRhi::Feature feature) const
         return true;
     case QRhi::NPOTTextureRepeat:
         return true;
+    case QRhi::RedOrAlpha8IsRed:
+        return true;
     default:
         Q_UNREACHABLE();
         return false;