Add a blend_test sample

samples/Makefile

@@ -27,3 +27,4 @@ all:
 	$(KOS_MAKE) -C depth_funcs all
 	$(KOS_MAKE) -C polymark all
 	$(KOS_MAKE) -C polygon_offset all
+	$(KOS_MAKE) -C blend_test all

samples/blend_test/Makefile

@@ -0,0 +1,29 @@
+TARGET = blend_test.elf
+OBJS = main.o
+
+all: rm-elf $(TARGET)
+
+include $(KOS_BASE)/Makefile.rules
+
+clean:
+	-rm -f $(TARGET) $(OBJS) romdisk.*
+
+rm-elf:
+	-rm -f $(TARGET) romdisk.*
+
+$(TARGET): $(OBJS) romdisk.o
+	$(KOS_CC) $(KOS_CFLAGS) $(KOS_LDFLAGS) -o $(TARGET) $(KOS_START) \
+		$(OBJS) romdisk.o $(OBJEXTRA) -lm -lkosutils $(KOS_LIBS)
+
+romdisk.img:
+	$(KOS_GENROMFS) -f romdisk.img -d romdisk -v
+
+romdisk.o: romdisk.img
+	$(KOS_BASE)/utils/bin2o/bin2o romdisk.img romdisk romdisk.o
+
+run: $(TARGET)
+	$(KOS_LOADER) $(TARGET)
+
+dist:
+	rm -f $(OBJS) romdisk.o romdisk.img
+	$(KOS_STRIP) $(TARGET)

samples/blend_test/main.c

@@ -0,0 +1,100 @@
+/*
+ * This sample is to demonstrate a bug where rendering an unblended
+ * polygon, before a series of blended ones would result in no blended
+ * output and incorrect depth testing
+ */
+
+#include "gl.h"
+#include "glu.h"
+#include "glkos.h"
+
+/* A general OpenGL initialization function.  Sets all of the initial parameters. */
+void InitGL(int Width, int Height)	        // We call this right after our OpenGL window is created.
+{
+    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);		// This Will Clear The Background Color To Black
+    glClearDepth(1.0);				// Enables Clearing Of The Depth Buffer
+    glDepthFunc(GL_LEQUAL);				// The Type Of Depth Test To Do
+    glEnable(GL_DEPTH_TEST);			// Enables Depth Testing
+    glEnable(GL_TEXTURE_2D);
+    glShadeModel(GL_SMOOTH);			// Enables Smooth Color Shading
+    glDisable(GL_BLEND);
+
+    glMatrixMode(GL_PROJECTION);
+    glLoadIdentity();				// Reset The Projection Matrix
+
+    gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f);	// Calculate The Aspect Ratio Of The Window
+
+    glMatrixMode(GL_MODELVIEW);
+}
+
+/* The function called when our window is resized (which shouldn't happen, because we're fullscreen) */
+void ReSizeGLScene(int Width, int Height)
+{
+    if (Height == 0)				// Prevent A Divide By Zero If The Window Is Too Small
+        Height = 1;
+
+    glViewport(0, 0, Width, Height);		// Reset The Current Viewport And Perspective Transformation
+
+    glMatrixMode(GL_PROJECTION);
+    glLoadIdentity();
+
+    gluPerspective(45.0f,(GLfloat)Width/(GLfloat)Height,0.1f,100.0f);
+    glMatrixMode(GL_MODELVIEW);
+}
+
+
+void DrawQuad(const float* colour) {
+    glBegin(GL_QUADS);
+    glColor4fv(colour);
+    glVertex3f(-1.0,-1.0, 0.0);
+    glVertex3f( 1.0,-1.0, 0.0);
+    glVertex3f( 1.0, 1.0, 0.0);
+    glVertex3f(-1.0, 1.0, 0.0);
+    glEnd();
+}
+
+/* The main drawing function. */
+void DrawGLScene()
+{
+    const float RED [] = {1.0, 0, 0, 0.5};
+    const float BLUE [] = {0.0, 0, 1, 0.5};
+    const float NONE [] = {0, 0, 0, 0};
+
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);		// Clear The Screen And The Depth Buffer
+    glLoadIdentity();				// Reset The View
+
+    glTranslatef(0, 0, -10.0f);		// Move Left 1.5 Units And Into The Screen 6.0
+
+    glPushMatrix();
+    glTranslatef(-4.0, 0, -10);
+    DrawQuad(RED);
+    glPopMatrix();
+
+    glTranslatef(4.0, 0, 0);
+    glEnable(GL_BLEND);
+    glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+
+    /* Draw 3 overlapping quads, 2 of which should be totally transparent so the
+     * output should be the third */
+    DrawQuad(NONE);
+    DrawQuad(NONE);
+    DrawQuad(BLUE);
+
+    glDisable(GL_BLEND);
+
+    glKosSwapBuffers();
+}
+
+int main(int argc, char **argv)
+{
+    glKosInit();
+
+    InitGL(640, 480);
+    ReSizeGLScene(640, 480);
+
+    while(1) {
+        DrawGLScene();
+    }
+
+    return 0;
+}