Make sure we have access to the visible bitmask

GL/clip.c

@@ -39,7 +39,7 @@ ClipResult clipLineToNearZ(const float* v1, const float* v2, const float dist, f
 TriangleClipResult clipTriangleToNearZ(
     const float plane_dist,
     const unsigned short triangle_n, const pvr_vertex_t* v1, const pvr_vertex_t* v2, const pvr_vertex_t *v3,
-    pvr_vertex_t* v1out, pvr_vertex_t* v2out, pvr_vertex_t* v3out, pvr_vertex_t* v4out
+    pvr_vertex_t* v1out, pvr_vertex_t* v2out, pvr_vertex_t* v3out, pvr_vertex_t* v4out, unsigned char* visible
 ) {
 
     /* Fast out. Let's just see if everything is in front of the clip plane (and as in OpenGL Z comes out of the screen
@@ -47,9 +47,9 @@ TriangleClipResult clipTriangleToNearZ(
      */
 
     typedef unsigned char uint8;
-    uint8 visible = ((v1->z <= -plane_dist) ? 1 : 0) | ((v2->z <= -plane_dist) ? 2 : 0) | ((v3->z <= -plane_dist) ? 4 : 0);
+    *visible = ((v1->z <= -plane_dist) ? 1 : 0) | ((v2->z <= -plane_dist) ? 2 : 0) | ((v3->z <= -plane_dist) ? 4 : 0);
 
-    switch(visible) {
+    switch(*visible) {
     case 0b000:
         /* If behind is zero, then none of the vertices are visible */
         return TRIANGLE_CLIP_RESULT_DROP_TRIANGLE;

GL/clip.h

@@ -59,7 +59,7 @@ typedef enum {
 TriangleClipResult clipTriangleToNearZ(
     const float plane_dist,
     const unsigned short triangle_n, const pvr_vertex_t* v1, const pvr_vertex_t* v2, const pvr_vertex_t *v3,
-    pvr_vertex_t* v1out, pvr_vertex_t* v2out, pvr_vertex_t* v3out, pvr_vertex_t* v4out
+    pvr_vertex_t* v1out, pvr_vertex_t* v2out, pvr_vertex_t* v3out, pvr_vertex_t* v4out, unsigned char* visible
 );
 
 #ifdef __cplusplus

GL/draw.c

@@ -267,7 +267,7 @@ static void submitVertices(GLenum mode, GLsizei first, GLsizei count, GLenum typ
     Triangle.vcount = 0;
 
     /* Loop 1. Calculate vertex colours, transform, but don't apply perspective division */
-    for(rel = 0, i = first; i < count; ++i, ++rel) {       
+    for(rel = 0, i = first; i < first + count; ++i, ++rel) {
         pvr_vertex_t* vertex = (pvr_vertex_t*) dst;
         vertex->u = vertex->v = 0.0f;
         vertex->argb = 0;
@@ -350,6 +350,7 @@ static void submitVertices(GLenum mode, GLsizei first, GLsizei count, GLenum typ
         Triangle.vcount++;
         if(Triangle.vcount == 3) {
             pvr_vertex_t clipped[4];
+            GLubyte visible; /* Bitmask of which of the 3 input vertices are visible */
 
             /* OK we have a whole triangle, we may have to clip */
             TriangleClipResult tri_result = clipTriangleToNearZ(
@@ -361,7 +362,8 @@ static void submitVertices(GLenum mode, GLsizei first, GLsizei count, GLenum typ
                 &clipped[0],
                 &clipped[1],
                 &clipped[2],
-                &clipped[3]
+                &clipped[3],
+                &visible
             );
 
             /* The potential 4 new vertices that can be output by clipping the triangle. Initialized in the below branches */
@@ -450,6 +452,8 @@ static void submitVertices(GLenum mode, GLsizei first, GLsizei count, GLenum typ
                     }
                 }
             } else if(tri_result == TRIANGLE_CLIP_RESULT_ALTERED_VERTICES) {
+                /* We're here because a single vertex was visible, the other two vertices were changed */
+
 
             } else if(tri_result == TRIANGLE_CLIP_RESULT_ALTERED_AND_CREATED_VERTEX) {
 

samples/zclip1/Makefile

@@ -0,0 +1,29 @@
+TARGET = zclip1.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/zclip1/main.c

@@ -0,0 +1,68 @@
+#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, 0.0f);		// This Will Clear The Background Color To Black
+    glDepthFunc(GL_LESS);				// The Type Of Depth Test To Do
+    glEnable(GL_DEPTH_TEST);			// Enables Depth Testing
+    glShadeModel(GL_SMOOTH);			// Enables Smooth Color Shading
+
+    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);
+}
+
+
+/* The main drawing function. */
+void DrawGLScene()
+{
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);		// Clear The Screen And The Depth Buffer
+    glLoadIdentity();				// Reset The View
+
+    glDisable(GL_CULL_FACE);
+
+    /* Draw a triangle intersecting the screen with a single vertex visible */
+    glBegin(GL_TRIANGLES);
+    glVertex3f(0.0f, 0.0f, -5.0f);
+    glVertex3f(-0.5f, -1.0f, 5.0f);
+    glVertex3f(0.5, -1.0f, 5.0f);
+    glEnd();
+
+    // swap buffers to display, since we're double buffered.
+    glKosSwapBuffers();
+}
+
+int main(int argc, char **argv)
+{
+    glKosInit();
+
+    InitGL(640, 480);
+    ReSizeGLScene(640, 480);
+
+    while(1) {
+        DrawGLScene();
+    }
+
+    return 0;
+}

samples/zclip2/Makefile

@@ -0,0 +1,29 @@
+TARGET = zclip2.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/zclip2/main.c

@@ -0,0 +1,79 @@
+#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, 0.0f);		// This Will Clear The Background Color To Black
+    glClearDepth(1.0);				// Enables Clearing Of The Depth Buffer
+    glDepthFunc(GL_LESS);				// The Type Of Depth Test To Do
+    glEnable(GL_DEPTH_TEST);			// Enables Depth Testing
+    glShadeModel(GL_SMOOTH);			// Enables Smooth Color Shading
+
+    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);
+}
+
+
+/* The main drawing function. */
+void DrawGLScene()
+{
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);		// Clear The Screen And The Depth Buffer
+    glLoadIdentity();				// Reset The View
+
+    glTranslatef(-1.5f,0.0f,-6.0f);		// Move Left 1.5 Units And Into The Screen 6.0
+
+    // draw a triangle
+    glBegin(GL_POLYGON);				// start drawing a polygon
+    glVertex3f( 0.0f, 1.0f, 0.0f);		// Top
+    glVertex3f( 1.0f,-1.0f, 0.0f);		// Bottom Right
+    glVertex3f(-1.0f,-1.0f, 0.0f);		// Bottom Left
+    glEnd();					// we're done with the polygon
+
+    glTranslatef(3.0f,0.0f,0.0f);		        // Move Right 3 Units
+
+    // draw a square (quadrilateral)
+    glBegin(GL_QUADS);				// start drawing a polygon (4 sided)
+    glVertex3f(-1.0f, 1.0f, 0.0f);		// Top Left
+    glVertex3f( 1.0f, 1.0f, 0.0f);		// Top Right
+    glVertex3f( 1.0f,-1.0f, 0.0f);		// Bottom Right
+    glVertex3f(-1.0f,-1.0f, 0.0f);		// Bottom Left
+    glEnd();					// done with the polygon
+
+    // swap buffers to display, since we're double buffered.
+    glKosSwapBuffers();
+}
+
+int main(int argc, char **argv)
+{
+    glKosInit();
+
+    InitGL(640, 480);
+    ReSizeGLScene(640, 480);
+
+    while(1) {
+        DrawGLScene();
+    }
+
+    return 0;
+}