Add gluOrtho2D, ortho2d example and fix glOrtho

GL/glu.c

@@ -2,7 +2,7 @@
 #include "private.h"
 
 /* Set the Perspective */
-void gluPerspective(GLfloat angle, GLfloat aspect,
+void APIENTRY gluPerspective(GLfloat angle, GLfloat aspect,
                     GLfloat znear, GLfloat zfar) {
     GLfloat xmin, xmax, ymin, ymax;
 
@@ -13,3 +13,7 @@ void gluPerspective(GLfloat angle, GLfloat aspect,
 
     glFrustum(xmin, xmax, ymin, ymax, znear, zfar);
 }
+
+void APIENTRY gluOrtho2D(GLdouble left, GLdouble right, GLdouble bottom, GLdouble top) {
+    glOrtho(left, right, bottom, top, -1.0f, 1.0f);
+}

GL/matrix.c

@@ -176,9 +176,9 @@ void APIENTRY glOrtho(GLfloat left, GLfloat right,
     OrthoMatrix[3][1] = -(top + bottom) / (top - bottom);
     OrthoMatrix[3][2] = -(zfar + znear) / (zfar - znear);
 
-    mat_load(stack_top(MATRIX_STACKS + MATRIX_MODE));
+    mat_load(stack_top(MATRIX_STACKS + MATRIX_IDX));
     mat_apply(&OrthoMatrix);
-    mat_store(stack_top(MATRIX_STACKS + MATRIX_MODE));
+    mat_store(stack_top(MATRIX_STACKS + MATRIX_IDX));
 }
 
 
@@ -207,18 +207,6 @@ void APIENTRY glFrustum(GLfloat left, GLfloat right,
     mat_store(stack_top(MATRIX_STACKS + MATRIX_IDX));
 }
 
-/* Set the Perspective */
-void gluPerspective(GLfloat angle, GLfloat aspect,
-                    GLfloat znear, GLfloat zfar) {
-    GLfloat xmin, xmax, ymin, ymax;
-
-    ymax = znear * ftan(angle * F_PI / 360.0f);
-    ymin = -ymax;
-    xmin = ymin * aspect;
-    xmax = ymax * aspect;
-
-    glFrustum(xmin, xmax, ymin, ymax, znear, zfar);
-}
 
 /* Multiply the current matrix by an arbitrary matrix */
 void glMultMatrixf(const GLfloat *m) {

Makefile

@@ -6,7 +6,7 @@
 # Copyright (C) 2018 Luke Benstead
 
 TARGET = libGLdc.a
-OBJS = GL/draw.o GL/flush.o GL/framebuffer.o GL/immediate.o GL/lighting.o GL/state.o GL/texture.o
+OBJS = GL/draw.o GL/flush.o GL/framebuffer.o GL/immediate.o GL/lighting.o GL/state.o GL/texture.o GL/glu.o
 OBJS += GL/matrix.o GL/fog.o GL/error.o containers/stack.o containers/named_array.o containers/aligned_vector.o
 
 SUBDIRS =

include/glu.h

@@ -23,6 +23,8 @@ __BEGIN_DECLS
 #define GLU_FALSE 0
 #define GLU_TRUE  1
 
+GLAPI void APIENTRY gluOrtho2D(GLdouble left, GLdouble right, GLdouble bottom, GLdouble top);
+
 /* gluPerspective - Set the Perspective for Rendering. */
 GLAPI void APIENTRY gluPerspective(GLdouble fovy, GLdouble aspect,
                                    GLdouble zNear, GLdouble zFar);

samples/Makefile

@@ -10,4 +10,5 @@ all:
 	$(KOS_MAKE) -C nehe02 all
 	$(KOS_MAKE) -C nehe02va all
 	$(KOS_MAKE) -C nehe03 all
-	$(KOS_MAKE) -C nehe06 all
+	$(KOS_MAKE) -C nehe06 all
+	$(KOS_MAKE) -C ortho2d all

samples/ortho2d/Makefile

@@ -0,0 +1,29 @@
+TARGET = ortho2d.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/ortho2d/main.c

@@ -0,0 +1,67 @@
+#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
+
+    gluOrtho2D(0, 640, 0, 480);
+
+    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();
+
+    gluOrtho2D(0, 640, 0, 480);
+
+    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
+
+    // draw a triangle
+    glBegin(GL_TRIANGLES);				// start drawing a polygon
+    glVertex2f( 320.0f, 360.0f);		// Top
+    glVertex2f( 120.0f, 120.0f);
+    glVertex2f( 640.0f - 120.0f, 120.0f);
+    glEnd();					// we're done with the polygon
+
+    glKosSwapBuffers();
+}
+
+int main(int argc, char **argv)
+{
+    glKosInit();
+
+    InitGL(640, 480);
+    ReSizeGLScene(640, 480);
+
+    while(1) {
+        DrawGLScene();
+    }
+
+    return 0;
+}