[C99] Added "Offscreen" example written in C.

This example demonstrates how to render into a texture without ever creating a swap-chain.
LukasBanana · Jul 4, 2024 · 03d5419 · 03d5419
1 parent 63e9782
commit 03d5419
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Showing 9 changed files with 444 additions and 17 deletions.
diff --git a/.gitignore b/.gitignore
@@ -12,6 +12,7 @@ build*/
 # Runtime output files for testing
 Screenshot.*
 Capture.*
+*.Results.png
 
 # Output files from individual tests (Testbed is handled separately)
 tests/Output

diff --git a/examples/C99/CMakeLists.txt b/examples/C99/CMakeLists.txt
@@ -16,6 +16,7 @@ project(LLGL_ExamplesC99)
 find_source_files(FilesExampleBaseC99 C "${EXAMPLE_C99_PROJECTS_DIR}/ExampleBase")
 
 find_project_source_files( FilesExampleC99_HelloTriangle    "${EXAMPLE_C99_PROJECTS_DIR}/HelloTriangle" )
+find_project_source_files( FilesExampleC99_Offscreen        "${EXAMPLE_C99_PROJECTS_DIR}/Offscreen" )
 find_project_source_files( FilesExampleC99_Texturing        "${EXAMPLE_C99_PROJECTS_DIR}/Texturing"     )
 
 
@@ -53,6 +54,7 @@ if(LLGL_BUILD_EXAMPLES AND LLGL_BUILD_WRAPPER_C99)
 
     # C99 wrapper examples
     add_llgl_example_project(Example_C99_HelloTriangle  C "${FilesExampleC99_HelloTriangle}"    "${EXAMPLE_C99_PROJECT_LIBS}")
+    add_llgl_example_project(Example_C99_Offscreen      C "${FilesExampleC99_Offscreen}"        "${EXAMPLE_C99_PROJECT_LIBS}")
     add_llgl_example_project(Example_C99_Texturing      C "${FilesExampleC99_Texturing}"        "${EXAMPLE_C99_PROJECT_LIBS}")
 endif()
 

diff --git a/examples/C99/ExampleBase/ExampleBase.c b/examples/C99/ExampleBase/ExampleBase.c
@@ -100,22 +100,14 @@ static void mouse_motion_event(LLGLWindow sender, const LLGLOffset2D* motion)
  * Global functions
  */
 
-struct ExampleConfig
-{
-    const char* rendererModule;
-    uint32_t    windowSize[2];
-    uint32_t    samples;
-    bool        vsync;
-    bool        debugger;
-};
-
 static struct ExampleConfig g_Config =
 {
     .rendererModule = "OpenGL",
     .windowSize     = { 800, 600 },
     .samples        = 8,
     .vsync          = true,
     .debugger       = false,
+    .noDepthStencil = false
 };
 
 static void update_viewport()
@@ -138,6 +130,33 @@ static float aspect_ratio()
     return (float)swapChainResolution.width / (float)swapChainResolution.height;
 }
 
+void example_config(const ExampleConfig* config)
+{
+    if (config != NULL)
+    {
+        if (config->rendererModule != NULL)
+            g_Config.rendererModule = config->rendererModule;
+        if (config->windowSize[0] != 0)
+            g_Config.windowSize[0] = config->windowSize[0];
+        if (config->windowSize[1] != 0)
+            g_Config.windowSize[1] = config->windowSize[1];
+        g_Config.samples        = config->samples;
+        g_Config.vsync          = config->vsync;
+        g_Config.debugger       = config->debugger;
+        g_Config.noDepthStencil = config->noDepthStencil;
+    }
+    else
+    {
+        g_Config.rendererModule = "OpenGL";
+        g_Config.windowSize[0]  = 800;
+        g_Config.windowSize[1]  = 600;
+        g_Config.samples        = 8;
+        g_Config.vsync          = true;
+        g_Config.debugger       = false;
+        g_Config.noDepthStencil = false;
+    }
+}
+
 int example_init(const wchar_t* title)
 {
     // Register standard output as log callback
@@ -155,10 +174,10 @@ int example_init(const wchar_t* title)
     LLGLSwapChainDescriptor swapChainDesc =
     {
         .resolution     = { g_Config.windowSize[0], g_Config.windowSize[1] },
-        .colorBits      = 32,   // 32 bits for color information
-        .depthBits      = 24,   // 24 bits for depth comparison
-        .stencilBits    = 8,    // 8 bits for stencil patterns
-        .samples        = g_Config.samples, // check if LLGL adapts sample count that is too high
+        .colorBits      = 32,                                   // 32 bits for color information
+        .depthBits      = (g_Config.noDepthStencil ? 0 : 24),   // 24 bits for depth comparison
+        .stencilBits    = (g_Config.noDepthStencil ? 0 : 8),    // 8 bits for stencil patterns
+        .samples        = g_Config.samples,                     // check if LLGL adapts sample count that is too high
     };
     g_swapChain = llglCreateSwapChain(&swapChainDesc);
 
@@ -249,10 +268,38 @@ bool example_poll_events()
 void perspective_projection(float outProjection[4][4], float aspectRatio, float nearPlane, float farPlane, float fieldOfView)
 {
     const int rendererID = llglGetRendererID();
-    if (rendererID == LLGL_RENDERERID_OPENGL || rendererID == LLGL_RENDERERID_VULKAN)
-        build_perspective_projection(outProjection, aspectRatio, nearPlane, farPlane, fieldOfView, /*isUnitCube:*/ true);
-    else
-        build_perspective_projection(outProjection, aspectRatio, nearPlane, farPlane, fieldOfView, /*isUnitCube:*/ false);
+    const bool isUnitCube = (rendererID == LLGL_RENDERERID_OPENGL || rendererID == LLGL_RENDERERID_VULKAN);
+    build_perspective_projection(outProjection, aspectRatio, nearPlane, farPlane, fieldOfView, isUnitCube);
+}
+
+static void build_orthogonal_projection(float m[4][4], float width, float height, float nearPlane, float farPlane, bool isUnitCube)
+{
+    m[0][0] = 2.0f / width;
+    m[0][1] = 0.0f;
+    m[0][2] = 0.0f;
+    m[0][3] = 0.0f;
+
+    m[1][0] = 0.0f;
+    m[1][1] = 2.0f / height;
+    m[1][2] = 0.0f;
+    m[1][3] = 0.0f;
+
+    m[2][0] = 0.0f;
+    m[2][1] = 0.0f;
+    m[2][2] = (isUnitCube ? 2.0f/(farPlane - nearPlane) : 1.0f/(farPlane - nearPlane));
+    m[3][2] = 0.0f;
+
+    m[3][0] = 0.0f;
+    m[3][1] = 0.0f;
+    m[2][3] = (isUnitCube ? -(farPlane + nearPlane)/(farPlane - nearPlane) : -nearPlane/(farPlane - nearPlane));
+    m[3][3] = 1.0f;
+}
+
+void orthogonal_projection(float outProjection[4][4], float width, float height, float nearPlane, float farPlane)
+{
+    const int rendererID = llglGetRendererID();
+    const bool isUnitCube = (rendererID == LLGL_RENDERERID_OPENGL || rendererID == LLGL_RENDERERID_VULKAN);
+    build_orthogonal_projection(outProjection, width, height, nearPlane, farPlane, isUnitCube);
 }
 
 void get_textured_cube(const TexturedVertex** outVertices, size_t* outVertexCount, const uint32_t** outIndices, size_t* outIndexCount)

diff --git a/examples/C99/ExampleBase/ExampleBase.h b/examples/C99/ExampleBase/ExampleBase.h
@@ -26,6 +26,17 @@
  * Structures
  */
 
+typedef struct ExampleConfig
+{
+    const char* rendererModule;
+    uint32_t    windowSize[2];
+    uint32_t    samples;
+    bool        vsync;
+    bool        debugger;
+    bool        noDepthStencil;
+}
+ExampleConfig;
+
 typedef struct TexturedVertex
 {
     float position[3];
@@ -91,6 +102,9 @@ extern float                g_projection[4][4];
  * Global functions
  */
 
+// Configures the example setup. If used, it must be called before example_init(). If this is NULL, the defualt configuration will be used.
+void example_config(const ExampleConfig* config);
+
 // Initializes the example with the specified title and returns a non-zero error code if initialization failed.
 int example_init(const wchar_t* title);
 
@@ -103,6 +117,9 @@ bool example_poll_events();
 // Builds a perspective projection matrix.
 void perspective_projection(float outProjection[4][4], float aspectRatio, float nearPlane, float farPlane, float fieldOfView);
 
+// Builds an orthogonal projection matrix.
+void orthogonal_projection(float outProjection[4][4], float width, float height, float nearPlane, float farPlane);
+
 // Returns the pointers the vertex and index data of a textured cube.
 void get_textured_cube(const TexturedVertex** outVertices, size_t* outVertexCount, const uint32_t** outIndices, size_t* outIndexCount);