Fix bug when clipping triangle strips

GL/clip.c

@@ -228,7 +228,6 @@ void clipTriangleStrip(AlignedVector* vertices, AlignedVector* outBuffer) {
 
             ClipVertex output[4];
 
-            /* FIXME: Interpolate other values (colors etc.) */
             clipLineToNearZ(v2->xyz, v3->xyz, CLIP_DISTANCE, output[2].xyz, &t1);
             clipLineToNearZ(v1->xyz, v3->xyz, CLIP_DISTANCE, output[3].xyz, &t2);
 
@@ -261,7 +260,6 @@ void clipTriangleStrip(AlignedVector* vertices, AlignedVector* outBuffer) {
 
             ClipVertex output[4];
 
-            /* FIXME: Interpolate other values (colors etc.) */
             clipLineToNearZ(v1->xyz, v2->xyz, CLIP_DISTANCE, output[0].xyz, &t1);
             clipLineToNearZ(v1->xyz, v3->xyz, CLIP_DISTANCE, output[2].xyz, &t2);
 
@@ -294,26 +292,25 @@ void clipTriangleStrip(AlignedVector* vertices, AlignedVector* outBuffer) {
 
             ClipVertex output[4];
 
-            /* FIXME: Interpolate other values (colors etc.) */
             clipLineToNearZ(v1->xyz, v2->xyz, CLIP_DISTANCE, output[1].xyz, &t1);
-            clipLineToNearZ(v3->xyz, v2->xyz, CLIP_DISTANCE, output[2].xyz, &t2);
+            clipLineToNearZ(v3->xyz, v2->xyz, CLIP_DISTANCE, output[3].xyz, &t2);
 
             interpolateFloat(v1->w, v2->w, t1, &output[1].w);
-            interpolateFloat(v3->w, v2->w, t2, &output[2].w);
+            interpolateFloat(v3->w, v2->w, t2, &output[3].w);
 
             output[0] = *v1;
-            output[3] = *v3;
+            output[2] = *v3;
 
             /* Interpolate normals */
             interpolateVec3(v1->nxyz, v2->nxyz, t1, output[1].nxyz);
-            interpolateVec3(v3->nxyz, v2->nxyz, t2, output[2].nxyz);
+            interpolateVec3(v3->nxyz, v2->nxyz, t2, output[3].nxyz);
 
             /* Interpolate texcoords */
             interpolateVec2(v1->uv, v2->uv, t1, output[1].uv);
-            interpolateVec2(v3->uv, v2->uv, t2, output[2].uv);
+            interpolateVec2(v3->uv, v2->uv, t2, output[3].uv);
 
             interpolateColour((uint32_t*) &v1->argb, (uint32_t*) &v2->argb, t1, (uint32_t*) &output[1].argb);
-            interpolateColour((uint32_t*) &v3->argb, (uint32_t*) &v2->argb, t2, (uint32_t*) &output[2].argb);
+            interpolateColour((uint32_t*) &v3->argb, (uint32_t*) &v2->argb, t2, (uint32_t*) &output[3].argb);
 
             output[0].flags = VERTEX_CMD;
             output[1].flags = VERTEX_CMD;

GL/draw.c

@@ -392,7 +392,7 @@ static void divide(AlignedVector* vertices) {
     ClipVertex* vertex = (ClipVertex*) vertices->data;
 
     GLsizei i;
-    for(i = 0; i < vertices->size; ++i, ++vertex) {        
+    for(i = 0; i < vertices->size; ++i, ++vertex) {
         vertex->xyz[2] = 1.0f / vertex->w;
         vertex->xyz[0] *= vertex->xyz[2];
         vertex->xyz[1] *= vertex->xyz[2]; 

samples/Makefile

@@ -15,3 +15,4 @@ all:
 	$(KOS_MAKE) -C lerabot01 all
 	$(KOS_MAKE) -C zclip all
 	$(KOS_MAKE) -C zclip_triangle all
+	$(KOS_MAKE) -C zclip_trianglestrip all

samples/zclip_trianglestrip/Makefile

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

@@ -0,0 +1,99 @@
+#include <stdio.h>
+#include <string.h>
+#include <stdlib.h>
+
+#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_LEQUAL);				// The Type Of Depth Test To Do
+    glEnable(GL_DEPTH_TEST);			// Enables Depth Testing
+    glShadeModel(GL_SMOOTH);			// Enables Smooth Color Shading
+    glEnable(GL_TEXTURE_2D);
+
+    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);
+    glLoadIdentity();
+}
+
+/* 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()
+{
+    static GLfloat movement = 0.0f;
+    static GLboolean increasing = GL_TRUE;
+
+    if(movement > 10.0) {
+        increasing = GL_FALSE;
+    } else if(movement < -10.0f) {
+        increasing = GL_TRUE;
+    }
+
+    if(increasing) {
+        movement += 0.05f;
+    } else {
+        movement -= 0.05f;
+    }
+
+    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);		// Clear The Screen And The Depth Buffer
+    glLoadIdentity();				// Reset The View
+
+    glPushMatrix();
+        glTranslatef(0.0f, -1.0f, movement);
+
+        glBegin(GL_TRIANGLE_STRIP);
+            glColor3f(1.0f, 1.0f, 0.0f);
+            glVertex3f(-2.5f, 0.0f, -5.0f);
+
+            glColor3f(1.0f, 0.0f, 0.0f);
+            glVertex3f(-2.5f, 0.0f, 5.0f);
+
+            glColor3f(0.0f, 1.0f, 0.0f);
+            glVertex3f(2.5f, 0.0f, -5.0f);
+
+            glColor3f(0.0f, 0.0f, 1.0f);
+            glVertex3f(2.5f, 0.0f, 5.0f);
+        glEnd();
+    glPopMatrix();
+
+    // 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;
+}