exploring better stereo drawcall techniques

libraries/display-plugins/src/display-plugins/hmd/DebugHmdDisplayPlugin.cpp

@@ -26,6 +26,8 @@ bool DebugHmdDisplayPlugin::isSupported() const {
 
 void DebugHmdDisplayPlugin::resetSensors() {
     _currentRenderFrameInfo.renderPose = glm::mat4(); // identity
+    _currentRenderFrameInfo.renderPose = glm::translate(glm::mat4(), glm::vec3(0.0f, 1.76f, 0.0f));
+
 }
 
 bool DebugHmdDisplayPlugin::beginFrameRender(uint32_t frameIndex) {
@@ -35,6 +37,8 @@ bool DebugHmdDisplayPlugin::beginFrameRender(uint32_t frameIndex) {
     // FIXME simulate head movement
     //_currentRenderFrameInfo.renderPose = ;
     //_currentRenderFrameInfo.presentPose = _currentRenderFrameInfo.renderPose;
+    _currentRenderFrameInfo.renderPose = glm::translate(glm::mat4(), glm::vec3(0.0f, 1.76f, 0.0f));
+    _currentRenderFrameInfo.presentPose = _currentRenderFrameInfo.renderPose;
 
     withNonPresentThreadLock([&] {
         _frameInfos[frameIndex] = _currentRenderFrameInfo;
@@ -71,6 +75,7 @@ bool DebugHmdDisplayPlugin::internalActivate() {
     _eyeOffsets[1][3] = vec4{ 0.0327499993, 0.0, -0.0149999997, 1.0 };
     _renderTargetSize = { 3024, 1680 };
     _cullingProjection = _eyeProjections[0];
+
     // This must come after the initialization, so that the values calculated
     // above are available during the customizeContext call (when not running
     // in threaded present mode)

libraries/gpu-gl-common/src/gpu/gl/GLBackend.cpp

@@ -410,20 +410,24 @@ void GLBackend::render(const Batch& batch) {
         renderPassTransfer(batch);
     }
 
-#ifdef GPU_STEREO_DRAWCALL_INSTANCED
+//#ifdef GPU_STEREO_DRAWCALL_INSTANCED
+#ifdef GPU_STEREO_VIEWPORT_CLIPPED
     if (_stereo.isStereo()) {
         glEnable(GL_CLIP_DISTANCE0);
     }
 #endif
+//#endif
     {
         PROFILE_RANGE(render_gpu_gl_detail, _stereo.isStereo() ? "Render Stereo" : "Render");
         renderPassDraw(batch);
     }
-#ifdef GPU_STEREO_DRAWCALL_INSTANCED
+//#ifdef GPU_STEREO_DRAWCALL_INSTANCED
+#ifdef GPU_STEREO_VIEWPORT_CLIPPED
     if (_stereo.isStereo()) {
         glDisable(GL_CLIP_DISTANCE0);
     }
 #endif
+//#endif
 
     // Restore the saved stereo state for the next batch
     _stereo._enable = savedStereo;

libraries/gpu-gl-common/src/gpu/gl/GLBackend.h

@@ -36,7 +36,8 @@
 #define GPU_STEREO_TECHNIQUE_DOUBLED_SIMPLE
 #else
 //#define GPU_STEREO_TECHNIQUE_DOUBLED_SMARTER
-#define GPU_STEREO_TECHNIQUE_INSTANCED
+//#define GPU_STEREO_TECHNIQUE_INSTANCED
+#define GPU_STEREO_TECHNIQUE_INSTANCED_MULTIVIEWPORT
 #endif
 
 // Let these be configured by the one define picked above
@@ -51,6 +52,13 @@
 
 #ifdef GPU_STEREO_TECHNIQUE_INSTANCED
 #define GPU_STEREO_DRAWCALL_INSTANCED
+#define GPU_STEREO_VIEWPORT_CLIPPED 
+#define GPU_STEREO_CAMERA_BUFFER
+#endif
+
+#ifdef GPU_STEREO_TECHNIQUE_INSTANCED_MULTIVIEWPORT
+#define GPU_STEREO_DRAWCALL_INSTANCED
+#define GPU_STEREO_MULTI_VIEWPORT
 #define GPU_STEREO_CAMERA_BUFFER
 #endif
 

libraries/gpu-gl-common/src/gpu/gl/GLBackendTransform.cpp

@@ -39,6 +39,45 @@ void GLBackend::do_setViewportTransform(const Batch& batch, size_t paramOffset)
 
 #ifdef GPU_STEREO_DRAWCALL_INSTANCED
     {
+    #ifdef GPU_STEREO_MULTI_VIEWPORT
+        ivec4& vp = _transform._viewport;
+        auto sideWidth = vp.z / 2;
+
+        vec4 leftRight[3];
+
+        // Mono
+        leftRight[0] = vp;
+
+        // Left side
+        leftRight[1] = vp;
+        leftRight[1].x = 0;
+        leftRight[1].z = sideWidth;
+
+        // right side        
+        leftRight[2] = vp;
+        leftRight[2].x = sideWidth;
+        leftRight[2].z = sideWidth;
+
+        glViewportArrayv(0, 3, (float*)leftRight);
+
+        // Where we assign the GL viewport
+        if (_stereo.isStereo()) {
+            
+        //    ivec4 leftRight[3];
+        //    leftRight[0] = vp;
+            vp.z /= 2;
+         /*   leftRight[1] = vp; // left side
+            leftRight[2] = vp; // right side
+            leftRight[2].x += vp.z;
+            glViewportArrayv(0, 3, (float*) leftRight);
+*/
+            if (_stereo._pass) {
+                vp.x += vp.z;
+            }
+        } else {
+      //      glViewport(vp.x, vp.y, vp.z, vp.w);
+        }
+    #else
         ivec4& vp = _transform._viewport;
         glViewport(vp.x, vp.y, vp.z, vp.w);
 
@@ -49,6 +88,7 @@ void GLBackend::do_setViewportTransform(const Batch& batch, size_t paramOffset)
                 vp.x += vp.z;
             }
         }
+    #endif
     }
 #else
     if (!_inRenderTransferPass && !isStereo()) {

libraries/gpu/src/gpu/Transform.slh

@@ -168,10 +168,15 @@ TransformObject getTransformObject() {
         vec2 eyeOffsetScale = vec2(-0.5, +0.5);
         uint eyeIndex = uint(_stereoSide);
 #ifndef GPU_GLES
+#ifdef GPU_GL450
+        gl_ViewportIndex = _stereoSide + 1;
+      //  gl_ViewportIndex = 2 - _stereoSide;
+#else
         gl_ClipDistance[0] = dot(<$clipPos$>, eyeClipEdge[eyeIndex]);
 #endif
-        float newClipPosX = <$clipPos$>.x * 0.5 + eyeOffsetScale[eyeIndex] * <$clipPos$>.w;
+#endif
-        <$clipPos$>.x = newClipPosX;
+     //   float newClipPosX = <$clipPos$>.x * 0.5 + eyeOffsetScale[eyeIndex] * <$clipPos$>.w;
+     //   <$clipPos$>.x = newClipPosX;
 #endif
 
 #else

libraries/shaders/headers/450/header.glsl

@@ -1,4 +1,5 @@
 #version 450 core
+#extension GL_ARB_shader_viewport_layer_array : require
 #define GPU_GL450
 #define GPU_SSBO_TRANSFORM_OBJECT
 #define BITFIELD int

tools/shadergen.py

@@ -190,6 +190,10 @@ def processCommand(line):
         if (dialect == '310es'): spirvCrossDialect = '320es'
         spirvCrossArgs = [spirvCrossExec, '--output', glslFile, spirvFile, '--version', spirvCrossDialect]
         if (dialect == '410'): spirvCrossArgs.append('--no-420pack-extension')
+        if (dialect == '450'): 
+            spirvCrossArgs.append('--extension')
+            spirvCrossArgs.append('GL_ARB_shader_viewport_layer_array')
+            
         executeSubprocess(spirvCrossArgs)
     else:
         # This logic is necessary because cmake will agressively keep re-executing the shadergen