Handle GL applications changing BASE_LEVEL / MAX_LEVEL dynamically

* This is the only way in GL to do rendering from one mip to another. We handle
  it and display the whole texture even if it's temporarily constricted, and
  display the mip state in the pipeline viewer.
* If the mip state is constricted at the start of the frame capture, only mips
  0..MAX will be visible at all and other mips will be assumed to not be valid.

util/test/demos/d3d11/d3d11_mip_gen_rt.cpp

@@ -24,7 +24,7 @@
 
 #include "d3d11_test.h"
 
-struct Mip_Gen_RT : D3D11GraphicsTest
+struct D3D11_Mip_Gen_RT : D3D11GraphicsTest
 {
   static constexpr const char *Description =
       "Tests rendering from one mip to another to do a downsample chain";
@@ -155,4 +155,4 @@ float4 main(v2f IN) : SV_Target0
   }
 };
 
-REGISTER_TEST(Mip_Gen_RT);
+REGISTER_TEST(D3D11_Mip_Gen_RT);

util/test/demos/demos.vcxproj

@@ -167,6 +167,7 @@
     <ClCompile Include="gl\gl_large_bcn_arrays.cpp" />
     <ClCompile Include="gl\gl_map_overrun.cpp" />
     <ClCompile Include="gl\gl_midframe_context_create.cpp" />
+    <ClCompile Include="gl\gl_mip_gen_rt.cpp" />
     <ClCompile Include="gl\gl_multi_window.cpp" />
     <ClCompile Include="gl\gl_overlay_test.cpp" />
     <ClCompile Include="gl\gl_runtime_bind_prog_to_pipe.cpp" />

util/test/demos/demos.vcxproj.filters

@@ -240,6 +240,9 @@
     <ClCompile Include="vk\vk_video_textures.cpp">
       <Filter>Vulkan\demos</Filter>
     </ClCompile>
+    <ClCompile Include="gl\gl_mip_gen_rt.cpp">
+      <Filter>OpenGL\demos</Filter>
+    </ClCompile>
   </ItemGroup>
   <ItemGroup>
     <Filter Include="D3D11">

util/test/demos/gl/gl_mip_gen_rt.cpp

@@ -0,0 +1,180 @@
+/******************************************************************************
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2015-2018 Baldur Karlsson
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ ******************************************************************************/
+
+#include "gl_test.h"
+
+struct GL_Mip_Gen_RT : OpenGLGraphicsTest
+{
+  static constexpr const char *Description =
+      "Tests rendering from one mip to another to do a downsample chain";
+
+  std::string common = R"EOSHADER(
+
+#version 420 core
+
+#define v2f v2f_block \
+{                     \
+	vec4 pos;           \
+	vec4 col;           \
+	vec4 uv;            \
+}
+
+)EOSHADER";
+
+  std::string vertex = R"EOSHADER(
+
+out vec2 uv;
+
+void main()
+{
+  const vec4 verts[4] = vec4[4](vec4(-1.0, -1.0, 0.5, 1.0), vec4(1.0, -1.0, 0.5, 1.0),
+                                vec4(-1.0, 1.0, 0.5, 1.0), vec4(1.0, 1.0, 0.5, 1.0));
+
+  gl_Position = verts[gl_VertexID];
+  uv = gl_Position.xy * 0.5f + 0.5f;
+}
+
+)EOSHADER";
+
+  std::string pixel = R"EOSHADER(
+
+in vec2 uv;
+
+layout(location = 0, index = 0) out vec4 Color;
+
+layout(binding = 0) uniform sampler2D tex2D;
+
+void main()
+{
+	Color = textureLod(tex2D, -uv, 0.0f);
+}
+
+)EOSHADER";
+
+  int main(int argc, char **argv)
+  {
+    // initialise, create window, create context, etc
+    if(!Init(argc, argv))
+      return 3;
+
+    GLuint vao = MakeVAO();
+    glBindVertexArray(vao);
+
+    GLuint vb = MakeBuffer();
+    glBindBuffer(GL_ARRAY_BUFFER, vb);
+    glBufferStorage(GL_ARRAY_BUFFER, sizeof(DefaultTri), DefaultTri, 0);
+
+    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(DefaultA2V), (void *)(0));
+    glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, sizeof(DefaultA2V), (void *)(sizeof(Vec3f)));
+    glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(DefaultA2V),
+                          (void *)(sizeof(Vec3f) + sizeof(Vec4f)));
+
+    glEnableVertexAttribArray(0);
+    glEnableVertexAttribArray(1);
+    glEnableVertexAttribArray(2);
+
+    GLuint program = MakeProgram(common + vertex, common + pixel);
+    glObjectLabel(GL_PROGRAM, program, -1, "Full program");
+
+    GLuint tex = MakeTexture();
+    glBindTexture(GL_TEXTURE_2D, tex);
+    glTexStorage2D(GL_TEXTURE_2D, 8, GL_SRGB8_ALPHA8, 1024, 1024);
+
+    GLuint fbo[8];
+    for(int i = 0; i < 8; i++)
+    {
+      fbo[i] = MakeFBO();
+      glBindFramebuffer(GL_FRAMEBUFFER, fbo[i]);
+      glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, tex, i);
+    }
+
+    // fill upper mip with colour ramp
+    uint32_t *ramp = new uint32_t[1024 * 1024];
+    for(uint32_t i = 0; i < 1024 * 1024; i++)
+    {
+      float x = float(i % 1024);
+      float y = float(i / 1024);
+      ramp[i] = uint32_t(uint32_t(255.0f * (x / 1024.0f)) | (uint32_t(255.0f * (y / 1024.0f)) << 8) |
+                         (uint32_t(255.0f * ((x + y) / 2048.0f)) << 16) | 0xff000000);
+    }
+
+    while(Running())
+    {
+      float col[] = {0.4f, 0.5f, 0.6f, 1.0f};
+      glBindFramebuffer(GL_FRAMEBUFFER, 0);
+      glClearBufferfv(GL_COLOR, 0, col);
+
+      // clear all FBOs
+      for(int i = 0; i < 8; i++)
+      {
+        glBindFramebuffer(GL_FRAMEBUFFER, fbo[i]);
+        glClearBufferfv(GL_COLOR, 0, col);
+      }
+
+      glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+      glBindVertexArray(vao);
+
+      glUseProgram(program);
+
+      {
+        // view first mip and upload data
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 0);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 0);
+        glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, 1024, 1024, GL_RGBA, GL_UNSIGNED_BYTE, ramp);
+
+        for(int i = 1; i < 8; i++)
+        {
+          // bind relevant fbo
+          glBindFramebuffer(GL_FRAMEBUFFER, fbo[i]);
+
+          // change texture parameters to view previous mip
+          glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, i - 1);
+          glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, i - 1);
+
+          // set viewport
+          glViewport(0, 0, 1024 >> i, 1024 >> i);
+
+          // do downsample
+          glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+        }
+
+        // reset texture parameters to default
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_BASE_LEVEL, 4);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAX_LEVEL, 4);
+
+        // bind default framebuffer
+        glBindFramebuffer(GL_FRAMEBUFFER, 0);
+      }
+
+      Present();
+    }
+
+    delete[] ramp;
+
+    return 0;
+  }
+};
+
+REGISTER_TEST(GL_Mip_Gen_RT);