TINYGL: Support ColorMask

Note, this is just basic support, it is either all or nothing.
Disabling select channels is not possible.

graphics/tinygl/README.residualvm

@@ -14,3 +14,4 @@ The changes made from the original version of TinyGL 0.4 are:
 * Added support for reading in RGB/BGR-textures, although the only internal format is still RGB565
 * Added TGL_BGR/TGL_RGB definitions to gl.h, verifying against SDL_opengl.h that the values are ok.
 * Added additional functions missing, like glColor4ub. (To make the code similar with the GL-code we use)
+* Added simplistic glColorMask implementation, on/off.

graphics/tinygl/api.cpp

@@ -156,6 +156,15 @@ void tglFrontFace(int mode) {
 	TinyGL::gl_add_op(p);
 }
 
+void tglColorMask(TGLboolean r, TGLboolean g, TGLboolean b, TGLboolean a) {
+	TinyGL::GLParam p[2];
+
+	p[0].op = TinyGL::OP_ColorMask;
+	p[1].i = (r << 24) | (g << 16) | (b << 8) | (a << 0);
+
+	TinyGL::gl_add_op(p);
+}
+
 void tglPolygonMode(int face, int mode) {
 	TinyGL::GLParam p[3];
 

graphics/tinygl/clip.cpp

@@ -387,6 +387,10 @@ void gl_draw_triangle_fill(GLContext *c, GLVertex *p0, GLVertex *p1, GLVertex *p
 	}
 #endif
 
+	if (c->color_mask == 0) {
+		// FIXME: Accept more than just 0 or 1.
+		ZB_fillTriangleDepthOnly(c->zb, &p0->zp, &p1->zp, &p2->zp);
+	}
 	if (c->shadow_mode & 1) {
 		assert(c->zb->shadow_mask_buf);
 		ZB_fillTriangleFlatShadowMask(c->zb, &p0->zp, &p1->zp, &p2->zp);

graphics/tinygl/gl.h

@@ -790,6 +790,7 @@ void tglHint(int target, int mode);
 void tglGetIntegerv(int pname, int *params);
 void tglGetFloatv(int pname, float *v);
 void tglFrontFace(int mode);
+void tglColorMask(TGLboolean r, TGLboolean g, TGLboolean b, TGLboolean a);
 
 void tglSetShadowMaskBuf(unsigned char *buf);
 void tglSetShadowColor(unsigned char r, unsigned char g, unsigned char b);

graphics/tinygl/init.cpp

@@ -180,6 +180,8 @@ void glInit(void *zbuffer1) {
 
 	// depth test
 	c->depth_test = 0;
+
+	c->color_mask = (1 << 24) | (1 << 16) | (1 << 8) | (1 << 0);
 }
 
 void glClose() {

graphics/tinygl/misc.cpp

@@ -145,4 +145,8 @@ void  glopPolygonOffset(GLContext *c, GLParam *p) {
 	c->offset_units = p[2].f;
 }
 
+void glopColorMask(GLContext *c, TinyGL::GLParam *p) {
+	c->color_mask = p[1].i;
+}
+
 } // end of namespace TinyGL

graphics/tinygl/opinfo.h

@@ -48,6 +48,7 @@ ADD_OP(ShadeModel, 1, "%C")
 ADD_OP(CullFace, 1, "%C")
 ADD_OP(FrontFace, 1, "%C")
 ADD_OP(PolygonMode, 2, "%C %C")
+ADD_OP(ColorMask, 1, "%08x")
 
 ADD_OP(CallList, 1, "%d")
 ADD_OP(Hint, 2, "%C %C")

graphics/tinygl/zbuffer.h

@@ -98,6 +98,8 @@ void ZB_line_z(ZBuffer * zb, ZBufferPoint * p1, ZBufferPoint * p2);
 // ztriangle.c */
 
 void ZB_setTexture(ZBuffer *zb, const Graphics::PixelBuffer &texture);
+void ZB_fillTriangleDepthOnly(ZBuffer *zb, ZBufferPoint *p1,
+						 ZBufferPoint *p2, ZBufferPoint *p3);
 void ZB_fillTriangleFlat(ZBuffer *zb, ZBufferPoint *p1,
 						 ZBufferPoint *p2, ZBufferPoint *p3);
 void ZB_fillTriangleFlatShadowMask(ZBuffer *zb, ZBufferPoint *p1,

graphics/tinygl/zgl.h

@@ -272,6 +272,8 @@ typedef struct GLContext {
 
 	// depth test
 	int depth_test;
+
+	int color_mask;
 } GLContext;
 
 extern GLContext *gl_ctx;

graphics/tinygl/ztriangle.cpp

@@ -6,6 +6,23 @@ namespace TinyGL {
 
 #define ZCMP(z, zpix) ((z) >= (zpix))
 
+void ZB_fillTriangleDepthOnly(ZBuffer *zb, ZBufferPoint *p0, ZBufferPoint *p1, ZBufferPoint *p2) {
+
+#define INTERP_Z
+
+#define DRAW_INIT()
+
+#define PUT_PIXEL(_a) {						\
+	if (ZCMP(z, pz[_a])) {					\
+	pz[_a] = z;								\
+	}										\
+	z += dzdx;								\
+}
+
+#include "graphics/tinygl/ztriangle.h"
+}
+
+
 void ZB_fillTriangleFlat(ZBuffer *zb, ZBufferPoint *p0, ZBufferPoint *p1, ZBufferPoint *p2) {
 	int color;